Identify Weeds in Missouri
A weed is an out-of-place or unwanted plant. Weeds compete with wanted plants for water, nutrients, and sunlight. Weeds also interfere with the aesthetics and uniformity of ornamental beds and turfgrass areas, and cause problems in both field and container nurseries.
Weeds are opportunistic. They can be especially difficult to control in ornamental beds due to lack of natural competition. When bedding areas lack competition/weed barriers and mulches and when turfgrasses lack density, weeds fill in quickly under ideal weather conditions. Poor cultural practices, plant diseases and insect damage can lead to conditions that favor weeds.
Weeds affect desirable plants and land use in several ways:
- Reduce plant quality and vigor
- Increase costs - additional tillage, cultivation, and use of herbicides
- Increase labor and equipment costs
- Serve as host plants for diseases and insects
- Can be poisonous or irritating to animals or people - poison ivy, allergies, etc.
Identifying Weeds
The best control method for a weed depends on whether the weed is a winter annual, summer annual, biennial, cool-season, or warm-season perennial. The following weed descriptions are grouped according to those classifications.
Winter Annual Grassy Weeds
Annual Bluegrass
Weed Description
An erect or clump-forming annual grass that tolerates close mowing or may reach 11 inches in height. Primarily a weed of lawns and turfgrass, found throughout the United States.
Leaves
Light green in color when compared to other turfgrass species. Leaf blades are 1-5mm wide, folded in the bud, and lack hairs on both sides.
Stems
May be either erect or bending and may root at the base of the tillers.
Flowers
The seedhead is an open panicle, 3/4 to 2.5 inches long, and pyramidal in outline.
Roots
Fibrous
Identifying Characteristics
Light green grass with a boat-shaped leaf tip that resembles other lawn and turfgrass species. This weed is very similar to Kentucky Bluegrass (Poa pratensis) but is much lighter in color and lacks rhizomes.
Summer Annual Grassy Weeds
Barnyardgrass
Weed Description
A summer annual with thick stems that may reach 5 feet in height. One of the few grass weeds in which ligules are absent. Found throughout the United States, Canada, and Mexico as a weed of many agronomic crops, nurseries, landscapes, and turf.
Seedlings
Seeds are without hairs (glabrous), auricles, and ligules, and the leaf sheaths are often tinted red or maroon at the base.
Leaves
Rolled in the shoot, smooth and without ligules or auricles. Leaves range from 4 to 20 inches in length and may be 5-30 mm wide. Leaves have a distinct white midvein that becomes keeled toward the basal portions of the leaf. A few short hairs may occur at the leaf bases.
Stems
Usually erect, thick, without hairs (glabrous), often branched at the lower nodes, and may be tinted red to maroon at the base.
Flowers
Seedhead a terminal panicle ranging from 4 to 16 inches in length. Panicles may be green to purple in color and are comprised of individual spikelets that may develop a 2 to 10 mm long terminal awn.
Roots
A fibrous root system.
Identifying Characteristics
Prior to seedhead formation, Fall Panicum (Panicum Dichotomiflorum) and Barnyardgrass are often confused due to their similar growth habit and appearance. However, the characteristic absent ligule of Barnyardgrass helps to distinguish this weed from most other grasses in both the seedling and mature stage of growth.
Crabgrass
Weed Description
Shiny, yellowish-brown, 2-3 mm long.
Seedlings
Sheaths and blades usually densely hairy, with a jagged membranous ligule. Hairs on the blade and sheath are at a 90-degree angle to the plant surface. Seedlings are upright, leaves are rolled in the bud, and the first leaf blade is lanceolate to linear.
Leaves
Blades 1 1/4 to 8 inches long, 3-10 mm wide, with hairs on both surfaces. Sheaths hairy and closed. Ligules are 1-2 mm long, membranous and appearing as if cut off straight across the end, with uneven teeth or margin. Leaves and sheaths may turn dark red or maroon with age.
Stems
Prostrate, spreading, branched, and rooting at the nodes.
Flowers
Seed head composed of 4-6 branches (spikes) at the top of stems, each approximately 1 1/2 to 7 inches long. Spikelets are elliptic and in two rows along the spike.
Roots
Fibrous root system.
Identifying Characteristics
Densely hairy leaf and sheath and relatively large membranous ligule. Similar in appearance to Smooth Crabgrass (Digitaria Ishaemum), but smooth crabgrass does not have hairs on leaves and sheaths, only a few hairs may be found in the collar region. Additionally, large crabgrass roots at the stem nodes while smooth crabgrass does not.
Fall Panicum
Weed Description
A summer annual with large round, smooth sheaths that are often bent at the nodes. This weed may reach 7 feet in height and is found throughout most of the United States in various agronomic and horticultural crops, turfgrass, nurseries, landscapes, and non-crop areas. A primary identifying characteristic of this grass weed is the zigzagged growth pattern it takes on due to bending at the nodes.Seedlings
Fall panicum seedlings are much different from the mature plants in that the seedlings have many hairs on the lower surface of the leaf blades. Leaves are rolled in the shoot, the ligule is a fringe of hairs to 2 mm in length, and auricles are absent.Leaves
Rolled in the shoot, 15 to 20 mm wide, 4 to 20 inches long, and auricles are absent. The ligule is a fringe of hairs reaching 2 to 3 mm in length and is often fused at the base. Leaf blades have a conspicuous midvein and are smooth above but sometimes slightly hairy near the leaf tip or leaf base. The lower leaf surfaces of mature plants are without hairs (glabrous) and glossy.Stems
Stems are without hairs (glabrous), round, and sometimes glossy. Nodes along the stem are usually swollen and bent in different directions, which contributes to the rather unusual growth habit of this weed.Flowers
The seedhead is a wide, spreading panicle that develops a purplish tint when mature. Individual spikelets are yellow and approximately 3 mm long by 2 mm wide.Roots
A fibrous root system with stems that are capable of rooting at the nodes.Identifying Characteristics
Fall Panicum is often mistaken for Johnsongrass (Sorghum Halepense) or Barnyardgrass (Echinochloa Crus-Galli) prior to seedhead formation. However, johnsongrass has a membranous ligule unlike that of fall panicum and johnsongrass seedlings also do not have hairs on the lower leaf surface like those of fall panicum. Additionally, Barnyardgrass does not have a ligule at all and Barnyardgrass seedlings might only have hairs near the leaf base.
Foxtails
Weed Description
Foxtail millet is a stout summer annual that is believed to be native to temperate regions of Asia. Foxtail millet can also be found as a weed of cultivate areas, pastures, turf, and waste sites.
Leaves
Leaf widths vary from 5-21mm in width a membranous ligule is present with a fringe of trichomes.
Stems
Often pubescent at nodes, hollow, and occasionally branched at the base.
Flowers
Seedheads are panicles ranging from 2-20cm in length and 1-4cm in diameter. Bristles have short stiff hairs and seedheads often nodding, like other foxtail species.
Roots
Fibrous root system.
Identifying Characteristics
Nodding seedhead like other foxtail species, held up by a hollow stem. Foxtail millet has a short membranous ligule with a fringe of trichomes near the collar.
Perennial Grassy Weeds
Bermudagrass
Alternate names
Wire Grass
Weed Description
A perennial grass that has both rhizomes and stolons and can form a turf or mat of fine leaves. Several varieties of bermudagrass are cultivated for use as lawn and pasture grasses, however this weed has developed into a very troublesome and hard-to-control weed in agronomic crops, landscapes, nurseries, and turfgrass. Bermudagrass is found throughout the southern United States, as far north as southern New Jersey.
Seedlings
Leaves are rolled in the bud, leaf blades are smooth on both surfaces, and the ligule is a row of hairs approximately 1/2 mm long.
Leaves
Leaves are rolled in the bud, without auricles, and have a ligule that is a fringe of hairs approximately 1/2 mm long. Hairs occur at least on the leaf margins in the collar region (the region where the leaf blades join to the sheath). Leaf blades are approximately 2 to 7 inches long by 2 to 5 mm wide and smooth to only sparsely hairy above but usually only with a few hairs near the leaf base. Leaves emerge from opposite sides of the stem and have margins that are slightly rough.
Stems
Leaf sheaths are usually distinctly flattened with relatively long hairs (1 to 3 mm) near the collar only.
Flowers
Inflorescence consists of 3 to 7 fingerlike spikes that originate from a single point. Individual spikes are approximately 1 to 3 inches long and flattened. Spikelets are arranged in 2 rows on each spike and each of these spikelets produces a single lance-shaped seed (1 1/2 mm long).
Roots
Rhizomes and stolons both occur on the same plant. Rhizomes are scaly and often form an almost impenetrable mat. Stolons are flat, smooth, usually bent and root at the nodes.
Identifying Characteristics
A persistent grass weed with both scaly rhizomes and stolons that root at the nodes. Additionally, the tuft of hairs in the collar region helps to distinguish this weed from most other grasses. Nimblewill (Muhlenbergia Schreberi) is similar in appearance and growth habit, however Nimblewill plants are generally smaller than those of Bermudagrass and have a membranous ligule unlike the ligule that is a fringe of hairs on Bermudagrass.
Johnsongrass
Weed Description
A perennial from rhizomes that may reach 6 1/2 feet in height. Johnsongrass is capable of rapidly colonizing a variety of different environments due to the large amounts of seed and rhizomes produced by this plant. Originally introduced as a forage crop, this weed is now one of the most common and troublesome weeds of most agronomic and horticultural crops, as well as roadsides, pastures, and hay fields. Found in the United States from Massachusetts to Iowa, South to Florida and Texas, and in Southern California.
Seedlings
Leaves are rolled in the shoot, auricles are absent, and the ligule is membranous and may be toothed at the top. Leaf blades are without hairs (glabrous) on both surfaces and develop a prominent white midvein with maturity.
Leaves
Rolled in the shoot, without auricles, 6 to 20 inches long by 10 to 30 mm wide, with a prominent white midvein. Leaf blades are usually without hairs (glabrous) on both surfaces; however, some hairs may be present at the base of the leaf blade. The ligules are 3 to 4 mm long, membranous, and often toothed at the top. With maturity, some ligules may develop a fringe of hairs in the upper portion of the ligule and remain membranous towards the base.
Stems
Round to somewhat flattened, usually without hairs but sometimes hairs may be present along the margins. Sheaths may be green to maroon, especially near the base of the plant.
Flowers
Seedhead a large, open panicle, often with a purplish tint. Seed are oval, 3 to 5 mm in length, and dark red to black at maturity.
Roots
A fibrous root system and thick rhizomes.
Identifying Characteristics
Johnsongrass is often mistaken with Barnyardgrass (Echinochloa Crus-Galli) and/or Fall Panicum (Panicum Dichotomiflorum) prior to seedhead formation. However, Johnsongrass has a membranous ligule unlike that of Fall Panicum or Barnyardgrass and Johnsongrass seedlings do not have hairs on the lower leaf surface like those of Fall Panicum. Johnsongrass seedlings and mature plants also resemble Shattercane (Sorghum bicolor), but Shattercane does not have rhizomes like Johnsongrass.
Dallisgrass
Weed Description
A clump-forming perennial with a tall membranous ligule and a seedhead with many finger-like branches. Dallisgrass is primarily a weed of turfgrass and lawns, but also occurs in pastures, roadsides, and occasionally agronomic crops.
Seedlings
Leaf blades may be short hairy when young, but most older plants only have hairs in the collar regions. Leaves are rolled in the bud, have a tall, membranous ligule, and are without auricles.
Leaves
Leaves are rolled in the bud and lack auricles. Leaf blades range from 4 to 12 inches in length and 6 to 15 mm in width. Leaves are without hairs except for several long silky hairs that occur in the collar region. Ligules are membranous and from 1 to 3 mm tall.
Stems
Sheaths are compressed and mostly lack hairs. Sheaths are often tinted red with age. Plants can tolerate mowing but may also grow to a height of 5 feet when allowed to do so.
Flowers
The seedhead is produced on a terminal stalk that may reach 5 feet in height but is more commonly shorter due to close mowing. The seedhead is a raceme that has 3 to 5 finger-like spikes branching from the center. Each spike is from 2 to 4 inches long and contains 4 rows of spikelets that are each 3 to 4 mm long and covered with black silky hairs.
Roots
Fibrous roots and short rhizomes.
Identifying Characteristics
A perennial grass with short rhizomes, a tall ligule, and leaves with hairs near the collar only. The seedhead of Dallisgrass may be confused with that of Broadleaf Signalgrass (Brachiaria Platyphylla), however broadleaf Signalgrass has much shorter, wider leaves and a much shorter ligule that is a fringe of hairs.
Nimblewill
Weed Description
A perennial grass with stolons that forms dense mats and closely resembles bermudagrass. Nimblewill is primarily a weed of lawns and turfgrass, but can also occur in nurseries, orchards, and landscapes.
Seedlings
First leaves are long and wide. Leaves are rolled in the bud, without auricles, and with a very short membranous ligule.
Leaves
Leaf blades are relatively small, ranging from 3/4 to 3 inches in length and 2 to 4 mm in width. Leaf blades are mostly hairless except for some hairs near the ligule. Leaves are rolled in the bud and auricles are absent. The ligule is very short (about 1/2 mm) and membranous with distinctive teeth along the top.
Stems
Stems are branching, forming thick mats, and root at the nodes. Stems and stolons die early in the fall and form distinctive brown patches throughout lawns and turfgrass that are otherwise green. Leaf sheaths and stems are sometimes maroon tinted near the base.
Flowers
Seedheads are slender panicles, reaching as much as 6 inches in length. Each spike within the panicle contains spikelets that are approximately 2 mm long.
Roots
Nimblewill has a fibrous root system as well as stolons that run along the soil surface and root at the nodes.
Identifying Characteristics
The relatively short, narrow leaves, mat-forming habit, and stolons are all features that help to distinguish Nimblewill from most other grass species. Additionally, Nimblewill does not tolerate cool weather and forms very distinctive brown patches throughout the winter. Nimblewill is very similar to Bermudagrass (Cynodon Dactylon) but does not have rhizomes and is generally smaller and wirier in appearance than Bermudagrass. Nimblewill is very similar in appearance to Creeping Bentgrass (Agrostis Stolonifera), but this species has a much larger membranous ligule when compared to that of Nimblewill.
Quackgrass
Weed Description
A perennial grass weed from rhizomes that may reach 3 1/2 feet in height. Quackgrass is a common weed of agronomic crops, turfgrass, lawns, nurseries, and landscapes that may be found in the Northern United States from North Carolina to California.
Seedlings
First leaf is very long and wide and may have hairs or be hairless (glabrous) on the upper surface but are without hairs on the lower surface. Leaves are rolled in the bud and have membranous ligules that are very short (0.4 mm long). Seedlings have auricles but are often difficult to see on very young seedlings.
Leaves
Leaves are rolled in the bud and are approximately 1 1/2 to 12 inches long and usually 2 to 3 mm wide but may reach 12 mm in width. Leaves may or may not have hairs on the upper surfaces, but lower leaf surfaces are without hairs. Leaves have membranous ligules that are less than 1 mm long and have narrow auricles that clasp the sheath.
Stems
Leaf sheaths are rounded and may have short hairs, but hairs typically can be found only near the base of the plant. Stems often bend out and up from the base of the plant.
Flowers
Seedhead a long, narrow spike consisting of many individual spikelets arranged in 2 rows along the stem. Spikes range from 2 to 8 inches in length while individual spikelets are approximately 11 to 18 mm long with awns.
Roots
Rhizomes and a fibrous root system.
Identifying Characteristics
A perennial grass weed with auricles that clasp the stem, rhizomes, and a long, narrow spike for a seedhead. The auricle of this weed helps to immediately distinguish it from most other grass weeds, however Tall Fescue (Festuca Arundinacea), Annual Ryegrass (Lolium Multiflorum), and Perennial Ryegrass (Lolium Perenne) are similar grass weeds that also have auricles. However, none of these grass weeds have rhizomes like Quackgrass.
Miscellaneous Perennial Weeds
Yellow Nutsedge
Weed Description
A perennial from rhizomes and tubers that may reach 2 1/2 feet in height. The stems are 3-sided and triangular in cross section and the leaves are yellow to green in color with a distinct ridge. Found throughout North America as a common weed in agronomic and horticultural crops, nurseries, turfgrass, and landscapes.Seedlings
Seedlings rarely occur. Most plants arise from rhizomes and/or tubers. Leaves do not have ligules or auricles and have a distinct ridge along the midvein but are nevertheless often mistaken for grasses.Leaves
Yellow to green in color and have a distinctly shiny appearance. Leaves are 5 to 8 mm wide and have a distinct ridge along the midvein. Leaves are produced in groups of 3 from the base of the plant. Leaves are without hairs (glabrous) and no auricles or ligules are present. The leaves of yellow nutsedge taper gradually to a sharp point.Stems
Erect, unbranched, and 3-sided and triangular in cross section. Stems are usually solitary and produce terminal spikelets.Flowers
Spikelets occur at the ends of the solitary stems in a cluster where the flower stalks arise from a common point (umbel-like). Individual spikelets are yellow to brown in color.Roots
Rhizomes and tubers occur on the same plants. Tubers are round, ridged, initially white in color, eventually turning brown or black, and are sweet to the taste. Yellow nutsedge produces solitary tubers that arise either from the basal bulb or from a rhizome. Several tubers do not arise along the entire rhizome, as in purple nutsedge.Identifying Characteristics
Purple Nutsedge (Cyperus Rotundus) is very similar in appearance and growth habit to Yellow Nutsedge, and the two are often confused. However, the leaves of purple nutsedge taper to a point abruptly whereas those of Yellow Nutsedge gradually taper to a point. Additionally, the seedhead of purple nutsedge is purple in color, while that of Yellow Nusedge is yellow. Lastly, the tubers of purple nutsedge are often connected in chains and bitter to the taste, while those of Yellow Nutsedge are solitary and sweet to the taste. Rice Flatsedge (Cyperus Iria) and Green Kyllinga (Kyllinga Brevifolia) are also similar when young, however rice Flatsedge has a fibrous root system and Green Kyllinga has rhizomes that are usually red to purple in color.
Wild Garlic
Weed Description
A perennial from bulblets that emits a strong garlic or onion smell when crushed. Primarily a weed of small grains, turfgrass and pastures. Wild Garlic imparts a garlic-like flavor and odor on dairy and beef products when grazed. Additionally, small grains may become tainted with a garlic-like odor and/or flavor due to the presence of aerial bulblets at the time of harvest. Wild garlic is found throughout the eastern and central United States.Seedlings
Resemble those of a grass, but have hollow, round leaves.Leaves
Leaves are round, hollow, arising from a bulb, 6-24 inches long, 2-10 mm wide. All leaves have a garlic-like or onion scent.Stems
Flowering stems are the only stems that occur. These are slender, solid, waxy, unbranched, and 1-3 feet tall.Flowers
Flowers are produced at the top of the flowering stems. Flowers are greenish-white, small, and on short stems above the globe of aerial bulblets. Aerial bulblets are ovoid, often wholly or partially replace the flowers, and are usually tipped by a long, fragile slender green leaf.Fruit
The fruit is an egg-shaped 3-parted capsule.Roots
Round to egg-shaped bulbs with a papery outer covering. Smaller bulblets may form at the base of the bulbs, and fibrous roots are also attached at the bases of the bulbs.Identifying Characteristics
Round hollow leaves and garlic-like odor. Wild garlic is often confused with Wild Onion (Allium Canadense), but the two may be easily distinguished after a closer examination of the leaf cross section. The leaves of wild garlic are hollow and round, while those of wild onion are more flat and solid. Wild garlic is also like Star-of-Bethlehem (Ornithogalum Umbellatum), however this weed lacks the garlic-like odor of wild garlic and has distinctive white midveins that run the length of the leaf when mature. Starch Grapehyacinth (Muscari Racemosum) is also similar in appearance and growth habit but lacks the garlic-like odor as well.
Star-of-Bethlehem
Weed Description
A perennial from a bulb that is often misidentified as a grass or as wild garlic or wild onion. Star-of-Bethlehem has been sold as an ornamental and has escaped to become a weed of landscapes, pastures, hayfields, turfgrass, and lawns. Primarily distributed throughout the northern United States.Seedlings
Rarely occur. Most plants develop from bulbs.Leaves
The leaves are shiny, dark green, and have a distinct white midrib. Leaves are approximately 4 to 12 inches long, 2 to 6 mm wide, and are hollow in cross section. The leaves of this weed are commonly confused for a grass, but more closely resemble those of Wild Garlic. Leaves lack any garlic or onion-like smell.Stems
Leafless flowering stems occur that reach up to 12 inches in heightFlowers
Flowers consist of 6 white petals that collectively resemble a star. Flowers occur at the ends of leafless flowering stems.Fruit
A capsule that is 3-lobed and contains several oval black seed.Roots
Bulbs that are oval-shaped. Smaller bulblets occur around the parent bulb, and these bulblets are responsible for the spread of star-of-Bethlehem from one year to the next.Identifying Characteristics
A bulbous perennial with leaves that resemble Wild Garlic and have small, white, Star-shaped flowers. Star-of-Bethlehem is like Wild Garlic (Allium Vineale); however, Star-of-Bethlehem lacks the characteristic garlic smell and has distinctive white midveins along the leaves unlike wild garlic. Starch Grapehyacinth (Muscari Racemosum) is also similar in appearance, however this weed also lacks the distinctive white midveins that run the length of the leaves as in Star-of-Bethlehem.Winter Annual Broadleaf Weeds
Bedstraw
Alternate names
Smooth Bedstraw, Cleavers
Weed Description
A perennial with square stems and whorls of 6 to 8 leaves. Smooth bedstraw is primarily a weed of landscapes, nursery crops, turfgrass, and lawns that is found throughout the United States.
Seedlings
Plants normally spread via rhizomes and stolons therefore seedlings are rarely encountered. Cotyledons oval and occur on petioles that are notched at the apex.
Leaves
Occur in whorls of 6 to 8. Leaves are without hairs but may occasionally have hairs along the margins. Leaves are approximately 1/2 to 1 1/4 inches long by 2 to 4 mm wide. Leaves are without petioles (sessile).
Stems
Stems are square in cross-section and without hairs.
Flowers
Produced in clusters on a flower stalk that arises from the area between the stem and leaves (leaf axils). Flowers consist of 4 white petals.
Fruit
A 2-parted capsule that separates at maturity.
Roots
Rhizomes and stolons occur.
Identifying Characteristics
The whorled leaf of this plant makes it easily distinguishable from most other weeds except Field Madder (Sherardia Arvensis), which is very similar in appearance and growth habit. However, catchweed Bedstraw has hairs on the upper leaf surfaces and has stems with tiny prickles. Field madder generally has smaller leaves than the Bedstraws and the leaves occur in whorls of 4 to 6. The leaves of field madder are also more lanceolate and have much more of a distinct point than those of the Bedstraw species.
Common Chickweed
Weed Description
Prostrate, winter annual that is found throughout North America except for in the far west. Common Chickweed is primarily a weed of turfgrass, lawns and winter small grains.
Seedlings
Cotyledons are ovate, 1-12 mm long by 0.25-2 mm wide, with a slender reddish hypocotyl that is sparsely hairy.
Leaves
Arranged oppositely, oval, or elliptic in outline. Leaves range from 1/2 to 1 1/4 inches in length, are light green in color and smooth or possibly hairy toward base and on the petioles. Upper leaves are without petioles (sessile), while lower leaves are long petiolate.
Stems
Usually running prostrate along the ground, rooting at the nodes, with the upper portion erect or ascending and freely branching. Stems are light green in color and with hairs in vertical rows.
Flowers
Alone or in small clusters at the ends of stems. Flowers are small (3-6 mm wide) and consist of 5 white petals that are deeply lobed, giving the appearance of 10 petals.
Fruits
An oval, one-celled capsule, whitish in color, containing numerous seeds.
Roots
A shallow, fibrous root system.
Identifying Characteristics
The oppositely arranged small oval or elliptic leaves and stems with rows of hairs are both characteristics that help in the identification of Common Chickweed. Mouse-Ear Chickweed (Cerastium Vulgatum) is very similar in appearance and growth habit; however, this species is densely covered with hairs unlike Common Chickweed.
Purple Deadnettle
Alternate names
Red Deadnettle
Weed Description
Winter annual with square stems and purple-red flowers that closely resembles Henbit (Lamium Amplexicaule). Primarily a weed of turfgrass, landscapes, and winter grain crops found throughout the U.S.
Seedlings
Cotyledons oval and without hairs, while subsequent leaves are hairy, opposite, and nearly circular in outline with rounded teeth on the sides.
Leaves
All leaves occur on short petioles, are sparsely hairy, and are circular in outline with scalloped margins. Leaves are 8-12 mm long and dark green in color, becoming more purple red in the upper leaves. Upper leaves are also relatively triangular in outline.
Stems
Branched from the base of the plant, are square, and may reach 16-18 inches in height.
Flowers
Occur in whorls of 3-6 in the upper leaves. Purple red in color and 1-2 cm long.
Fruits
A berry 2 mm long.
Roots
Fibrous root system.
Identifying Characteristics
Winter annual with purple-red flowers, square stems, and petiole leaves. The petiole leaves, triangular and sometimes purplish-red upper leaves help to distinguish this weed from Henbit (Lamium Amplexicaule), which has upper leaves that do not occur on petioles (Sessile).
Henbit
Weed Description
Winter annual with square stems and pink-purple flowers, reaching 16 inches in height. Primarily a weed of turfgrass, landscapes and small grains. Found throughout the United States but most common in the eastern states.
Seedlings
Cotyledons are oval, 3-12 mm long, 1-4 mm wide. Stems below the cotyledons become purple with age. The base of the cotyledon is notched where it joins the petiole. Young leaves occur on petioles, are circular to heart-shaped, opposite, and have distinctly crinkled upper surfaces. Hairs occur on the upper leaf surfaces and along the veins of the lower surface.
Leaves
Opposite, reaching 5 inches in length, circular to heart-shaped, with hairs on the upper leaf surfaces and along the veins of the lower surface. Leaf margins have rounded teeth. Lower leaves occur on petioles, while the upper leaves are without petioles (sessile).
Stems
Lie on the ground but have tips that are ascending (decumbent), green or often purple-tinged. Stems root at the lower nodes, are square in cross section and are covered with downward-pointing hairs.
Flowers
Occur in whorls in the upper leaves without petioles. Flowers are pink to purple in color and are fused into a tube approximately 2/3 inch long.
Fruit
The fruit are egg-shaped nutlets reaching 2 mm in length and are brown with white spots.
Roots
Fibrous
Identifying Characteristics
Square stems with petiole lower leaves and sessile upper leaves. This weed is commonly confused with Purple Deadnettle (Lamium Purpureum). However, Purple Deadnettle has upper leaves that are triangular, occur on petioles, and are distinctly red or purple tinted, unlike the upper leaves of Henbit.
Shepard’s-Purse
Weed Description
Erect winter annual or biennial found in the entire Northwestern hemisphere invading cultivated areas, fields, pastures, roadsides, gardens, lawns, and waste sites. Shepherd’s Purse is native to southern Europe.
Seedlings
Hypocotyl light green to purple. Cotyledons are broadly spatulate in shape.
Leaves
Base of the plant is a basal rosette and is deeply toothed, then alternating leaves above, measuring 4-12cm in length and 1-3cm in width. Leaves are smooth or hairy and variously toothed or has small lobes extending beyond the stem.
Stems
Erect and slender covered with gray hairs and are normally unbranched.
Flowers
Are produced on an unbranched and indeterminate arrangement from spring to early summer and on some occasion’s late autumn. Flowers are small and difficult to see with the untrained eye and are white and green.
Fruit
Triangular to heart-shaped, two parted, and in a flattened pod.
Roots
Fibrous root system from a taproot that is slender and often branching.
Identifying Characteristics
Shepherd’s Purse is erect and has a rosette at the base with deeply toothed margins with smooth or hairy leaves. Identifying characteristics of Shepherd’s Purse are triangular or heart-shaped seedpods.
American Speedwell
Alternate names
American Brooklime
Weed Description
Aquatic Speedwells with attractive light blue flowers that are usually partly in and partly out of the water. American Speedwell can be found in swamps or along the banks of streams and ponds. American Speedwell is somewhat rare but can be found in Virginia, North Carolina, Tennessee, Kentucky, and West Virginia.
Leaves
Generally oval to elliptic in outline, widest at the base and pointed at the tip. Leaves are approximately 3/4 to 2 1/2 inches long, 1/2 to 3/4 inch wide. Leaves are usually shallowly toothed and occur on short petioles. The leaves that occur on the upper flowering stems clasp the stem at their base.
Stems
Growing prostrate along the ground with the flowering tips upright (decumbent growth habit). Stems may reach as much as 2 feet in length as they are capable of rooting at the nodes.
Flowers
Occur in clusters at the ends of the erect flowering stems. Flower clusters range from 2 to 6 inches in total length and contain many small light purples to light blue flowers. Each flower consists of 5 petals and is approximately 4 to 5 mm in total width.
Fruit
A capsule.
Identifying Characteristics
The aquatic growth habit, oval to elliptic leaves with petioles, and small light blue flowers are all characteristics that help in the identification of American Speedwell. Water Speedwell (Veronica Anagallis-Aquatica) is very similar in appearance and growth habit, however this species has leaves without petioles (Sessile) unlike American Speedwell. This weed may also be confused with Creeping Primrose (Ludwigia Palustris), however this aquatic weed generally has some portion of the plant under water, often has red-tinged foliage, and does not have blue flowers.
Carolina Geranium
Weed Description
Most often a biennial, forming a basal rosette initially with subsequent stem elongation and branching as the plant matures. May also occur as a winter or summer annual. Found throughout the United States.
Seedlings
Cotyledons are hairy, broad (6 mm wide), kidney-shaped, green above and pink below. Young leaves are hairy on both surfaces, alternate, and have leaf veins arising from a common point (palmately veined). Petioles of young plants are pink and covered with hairs that point downward. Margins of leaves are deeply lobed.
Leaves
Alternate near base, opposite above, and hairy on both surfaces. Leaves (3/4 to 2 1/2 inches wide) are rounded in appearance, and deeply (palmately) divided into 5-9 segments, with each segment also lobed or toothed.
Stems
Erect, freely branching near base to 28 inches tall. Stems are usually pink to red in color and densely hairy.
Flowers
Two or more in clusters at tips of stems and branches. Petals are whitish pink to pale purple in color, 4-6 mm long.
Roots
Fibrous with shallow taproot.
Summer Annual Broadleaf Weeds
Black Medic
Weed Description
A low-trailing summer annual, with yellow flowers. Found throughout the United States, primarily a weed of turfgrass.
Seedlings
Cotyledons oblong (4-9 mm long). First true leaf is borne on a single stalk, followed by leaves that consist of 3 leaflets and arise from a common point (palmately compound).
Leaves
Stems prostrate, 4-angled, hairy, radiating out from the taproot. Compound leaves are alternate, with wedge- to oval-shaped leaflets. Leaflets have toothed margins, are widest at the apex, and have a projecting tip in the center of the leaf. The central leaflet is borne on a short stalk, while the lateral leaflets arise from the central petiole. Stipules are present at the base of the petioles.
Flowers
Small and yellow, in clusters, approximately 1/2 to 3/4 inches long.
Fruit
A kidney-shaped, 1-seeded black pod, 2-3 mm long and hairy.
Roots
Taproot
Identifying Characteristics
This weed may easily be confused with other weedy trifoliate legumes such as hop clover, large hop clover, Yellow Woodsorrel (Oxalis Stricta), etc. However, the longer stalk of the central leaflet compared to lateral leaflets, small projecting tip at the leaflet apex, and toothed margins are important characteristics that help to distinguish Black Medic from other trifoliate legumes.
Carpetweed
Weed Description
A late-germinating, much-branched summer annual forming circular patches several feet in diameter.
Seedlings
Hypocotyl is short, green early turning brown with time. Cotyledons are oblong, thickened, smooth and 1.5 to 3.0 mm long.
Leaves
Smooth, in whorls of 3-8 at each node. Leaves are sessile, 1 to 3 cm long, widest above the middle and tapering to the base (Oblanceolate).
Stems
Smooth and much branched, lying on the ground with tips ascending (decumbent). Stems are green and 5 to 30 cm long.
Flowers
In clusters of 2 to 5 with slender 5-15 mm long stalks. Each flower is small (4-5 mm wide), and white in color.
Fruit
A small (1.5-4 mm long) three-parted, egg-shaped capsule containing small orange to red seeds.
Roots
Small, branched taproot.
Identifying Characteristics
Whorls of leaves at each stem node in addition to the circular, light green, mat-like growth.
Common Lespedeza
Alternate names
Japanese Clover
Weed Description
Prostrate, freely branched summer annual with inconspicuous purplish flowers forming mats 15 to 18 inches in diameter. Found throughout the southeast.
Leaves
Consist of 3 oblong leaflets (trifoliolate), 1/2 to 3/4 inch long and 1/3 to 1/2 as wide, obtuse at apex, narrowed at the base. Leaflets without hairs except for appressed hairs along the margins and midvein beneath. Lance-shaped stipules are present, 3-6 mm long, becoming brownish with age. Petioles are 1-2 mm long, much shorter than the leaves.
Stems
Freely branched stems with sparsely to densely appressed hairs that are bent or turned downward (Retrorse).
Flowers
Solitary or 2-5 in spike-like axillary racemes, pink to purple.
Fruit
A legume that is 3-4 mm long, tapering to a pointed apex.
Roots
Taproot.
Identifying Characteristics
Trifoliolate leaves with lance-shaped stipules, hairs along leaf margins, and pink to purple flowers. Common lespedeza is often confused with Black Medic (Medicago Lupulina), however the small spur at the tip of each leaflet and yellow flowers or Black Medic help to distinguish the two weeds.
Prostrate Knotweed
Alternate names
Wireweed
Weed Description
A prostrate summer annual with small, elliptic leaves that is primarily found in compacted areas of turfgrass such as pathways or sports fields. Prostrate Knotweed is found throughout the United States.
Seedlings
Cotyledons are narrow, linear in outline, often resembling and being mistaken for a grass. The stem below the cotyledons (Hypocotyl) is often reddish in color.
Leaves
Arranged alternately along the stem, lanceolate in outline, approximately 1/2 to 1 1/4 inches long and 1 to 8 mm wide. Leaves have short petioles and a distinctive thin membranous sheath (ocrea) that encircles the stem at the leaf base.
Stems
Branching, growing prostrate along the ground, ranging from 4 to 24 inches in length. Stems are swollen at the nodes with a thin membranous sheath (Ocrea) encircling the stem at each leaf base.
Flowers
Occur in the area between the stems and leaves (Leaf Axils). From 1 to 5 flowers occur in clusters and are very small and inconspicuous, white to pinkish white in color.
Fruit
A dark red to brown achene.
Roots
A taproot.
Identifying Characteristics
Prostrate-growing plants with small lanceolate leaves that are primarily found in hard compacted areas of turfgrass and landscapes. Some of the spurges like Spotted Spurge (Euphorbia Maculata) may be confused with Prostrate Knotweed, however the spurges do not have an ocrea and emit a milky sap when cut unlike Prostrate Knotweed.
Common Purslane
Weed Description
Prostrate, fleshy, succulent summer annual that can tolerate poor, compacted soils and drought. Common Purslane is a common weed of gardens, horticultural and agronomic crops and is found throughout the United States.
Seedlings
Cotyledons oblong, succulent and without hairs (Glabrous). Young leaves opposite with each succeeding pair 90 degrees from the preceding pair. Young leaves maroon or maroon-tinted on lower surface.
Leaves
Alternate or opposite, 1/4 to 1 1/4 inches long, rounded at apex and narrowed to the base (spatulate). Leaves are thick, succulent, and fleshy, with smooth margins.
Stems
Succulent, smooth, prostrate, much-branched, purplish-red or green, 4 to 20 inches long and without hairs.
Flowers
Yellow in color with 5 petals, 5-10 mm wide, that open only when sunny. Flowers are found alone in the leaf axils or clustered at the ends of the branches.
Fruit
An oval, many-seeded capsule (4-8 mm long by 3-5 mm wide) that splits open around the middle.
Roots
Taproot with fibrous secondary roots.
Identifying Characteristics
Prostrate growth habit in combination with the fleshy, succulent nature of this weed helps to distinguish it from most other plants.
Prostate Spurge
Weed Description
A prostrate summer annual that often forms dense mats that may reach 16 inches in diameter. All parts of the plant emit a milky sap when broken. Spotted spurge if found throughout the eastern half of the United States and in California and Oregon. This plant primarily occurs as a weed of landscapes, nurseries, turfgrass, lawns, and some agronomic crops.
Seedlings
Cotyledons are without hairs (Glabrous), oval, green above and tinted maroon below, and occur on short petioles that are maroon to purple in color. Stems below the cotyledons (Hypocotyls) are also without hair and pink to maroon in color.
Leaves
Egg-shaped in outline, 4 to 15 mm long, and usually without hairs but sometimes long hairs may occur. Leaves are arranged oppositely along the stem and often have a maroon spot on the upper leaf surface. Leaves occur on very short petioles and leaf margins may be very finely toothed (Often Indistinguishable) near the leaf apex.
Stems
Prostrate, branching out from a central point, densely hairy, and pink to red in color. Spotted spurge stems do not root at the nodes.
Flowers
Arise from the positions between the leaves and stems (Leaf Axils). Flowers are relatively inconspicuous.
Fruit
A hairy capsule approximately 1 1/2 mm long.
Roots
Small taproot and more noticeable fibrous root system.
Identifying Characteristics
Small prostrate plants that emit a milky sap when broken and form dense mats that radiate out from a central point. Spotted Spurge is very similar in appearance to Prostrate Spurge (Euphorbia Humistrata), however Prostrate Spurge roots at the nodes while Spotted Spurge does not. Prostrate Knotweed (Polygonum Aviculare) also grows prostrate and forms dense mats that radiate out from a central point, however Prostrate Knotweed has an ochrea and does not emit a milky sap like the spurges.
Cool-Season Perennial Broadleaf Weeds
Ground Ivy
Alternate names
Creeping Charlie
Weed Description
Perennial with creeping stems that root at the nodes and foliage that emits a mint-like odor when mowed. Primarily a weed of turfgrass and landscapes that is found in the northeastern, north central, and southern United States.
Seedlings
Although seedlings rarely occur due to the creeping stems and rhizomes, cotyledons are oblong to spatula shaped.
Leaves
Opposite, nearly round in outline or sometimes kidney-shaped, on long petioles. Margins have large, rounded teeth and leaf veins arise from the same point.
Stems
Square, trailing, rooting at the nodes, mostly without hair but occasionally with short, stiff backward-pointing hairs.
Flowers
Typically occur in clusters of 3 in the area between the stem and petiole (leaf axils). Flowers are blue-violet, 3/8 to 5/16 inch long.
Fruit
Small nutlets (1 mm long) that are egg-shaped and brown in color.
Roots
Rhizomes occur and fibrous roots are also produced at the base at each node of the trailing stem.
Identifying Characteristics
This weed is often misidentified as one of the speedwells or sometimes as Common Mallow (Malva Neglecta), but the square stems of ground ivy help to distinguish it from either of these weed species. Additionally, Henbit (Lamium Amplexicaule), Purple Deadnettle (Lamium Purpureum) and Persian Speedwell (Veronica Persica) are somewhat similar in appearance to Ground Ivy, but neither of these species have creeping stems that root at the nodes.
Mouse-Ear Chickweed
Weed Description
A spreading, mat-forming perennial with prominently hairy prostrate stems and leaves, resembling Common Chickweed. Found throughout the United States except extreme portions from Texas to California.
Seedlings
Cotyledons rounded to ovate, green, 2-7 mm long, 0.5-2 mm wide, bearing a few hairs at base of stalk.
Leaves
Opposite, dull-green, 1-2 cm long, 3-12 mm wide, oval to elliptic, lacking a petiole (sessile), with prominent hairs on upper surface and the veins beneath.
Stems
Slender, 1.5 to 5 cm long, with 2 rows of dense hairs, and root at the nodes when in contact with the soil.
Flowers
Usually in clusters of three at the end of stems. Flowers consist of 5 white petals that are deeply lobed, giving the appearance of 10 petals. Flowers are produced from May through October.
Fruit
Capsule that is cylindrical to slightly curved, membranous, 7-11 mm long, 2-3 mm wide, producing many seeds.
Roots
Fibrous and shallow.
Identifying Characteristics
Perennial growth habit with curved seed capsule. Very similar to Common Chickweed (Stellaria Media), however, Mouse-Ear Chickweed is densely pubescent and roots at the stem nodes.
White Clover
Weed Description
A perennial with trifoliate leaves, stems that root at the nodes, and white flowers. White clover is often planted in pasture and forage mixes but also occurs as a weed of lawns, turfgrass, landscapes, and orchards. White Clover is found throughout the United States.
Seedlings
Cotyledons are spatula-shaped, 6 to 7 mm long, without hairs. The first true leaf is solitary, oval, and cut off squarely at the base (Truncate). Subsequent leaves consist of three leaflets (Trifoliate).
Leaves
Leaves are composed of 3 leaflets (trifoliate). Each leaflet is egg-shaped, widest at the apex, 1/2 to 1 1/4 inches long, and has an indentation at the apex. Leaflets usually have a lighter green or white “V-shaped” marking close to their base and a slightly toothed margin. Each trifoliate leaf occurs on a 1–3-inch petiole.
Stems
Stems are low-growing, prostrate, usually without hairs but sometimes with short hairs, ranging from 4 to 16 inches in height. Stems root at the nodes.
Flowers
Occur on flower stalks (peduncles) that arise from the leaf axils. Each flower head is round or globular in outline, approximately 1/2 to 1 1/4 inches long, and consists of 20-40 individual white flowers.
Fruit
A pod known as a legume that is 4 to 5 mm long.
Roots
A fibrous root system with stems that root at the nodes.
Identifying Characteristics
The trifoliate leaves and white flowers are both key features that help in the identification of white clover. There are many other clover species that are planted in forages and occur as weeds. Red Clover (Trifolium Pratense) is similar but is generally more upright and taller, has larger leaflets, and generally larger, pink to red flowers. Alsike Clover (Trifolium Hybridum) also has white flowers but may be distinguished from white clover by the more upright, clump-forming habit and larger, more elongated leaflets.
Dandelion
Weed Description
A perennial from a basal rosette with yellow flowers and a puffball seedhead. Dandelion is one of the most common and problematic weeds of turfgrass and lawns throughout the United States. Dandelion also occurs as a weed of container ornamentals, landscapes, nurseries, orchards, and occasionally agronomic crops.
Seedlings
Cotyledons are light-green, smooth, and oval to spatulate in shape. Young leaves form a basal rosette and are also oval to spatulate in shape, 2 to 6 inches in length.
Leaves
Margins are noticeably wavy, especially on older leaves. All leaves are basal, ranging from 2 to 16 inches in length depending on the environment. Usually, leaves are more in the range of 2 to 8 inches in length. Leaves are oblong in outline, sometimes sparsely hairy, deeply indented with lobes that point toward the center of the rosette.
Stems
Erect, hollow flowering stems occur that are approximately 2 to 6 inches in height.
Flowers
Large, bright yellow in color, approximately 1 1/4 to 2 inches in diameter. Flowers are solitary on the end of unbranched, leafless, hollow stalks (Scape) that are 2 to 6 inches tall.
Fruit
An achene that is brown, 3-5 mm long, with a feathery pappus attached those aids in wind dispersal of seed. Collectively, the achenes form a white seedhead that resembles a puffball.
Roots
Deep taproot up to 1/2 inch in diameter.
Identifying Characteristics
The rosette growth habit, lobed leaves, yellow flowers, and characteristic puffball seedheads are all features that help in the identification of Dandelion. When in the rosette stage, Chicory (Cichorium Intybus) and Dandelion resemble one another. However, the lobes of chicory may point either toward the center of the rosette or away from the center of the rosette. Additionally, chicory has blue flowers and a flowering stem with alternately arranged leaves. White Flowered Mazus (Mazus Japonicus) also resembles Dandelion in the rosette stage of growth, however the leaves of this weed are not as severely lobed as those of Dandelion.
Curly Dock
Weed Description
Taproot perennial, developing a basal rosette of wavy-margined leaves and an unbranched stem that may reach 5 feet in height. Found throughout the United States primarily as a weed of pastures, hay fields, forages, landscapes, and some agronomic crops.
Seedlings
Stems below the cotyledons may be tinted maroon at the base. Cotyledons are rounded at the apex and narrowed to the base (Spatulate-Shaped). Cotyledons are without hairs and occur on petioles. Young leaves may have reddish patches on them and form a basal rosette.
Leaves
Lower rosette leaves are petiole, without hairs, alternately arranged on the stem, dark green with wavy margins. Stem leaves are arranged alternately along the stem, have a membranous sheath that encircles the stem (Ocrea), and become progressively smaller up the flowering stalk. Leaves become more reddish-purple with age.
Stems
Unbranched, thick, without hairs, ridged, often reddish in color.
Flowers
Occur in clusters on the upper portion of the elongating stem, consisting of greenish sepals that become reddish-brown with age.
Fruit
An achene (2 mm long) that is triangular, glossy, and brown to reddish-brown. A papery 3-valved or 3-winged structure surrounds the achene.
Roots
Large, fleshy taproot, yellowish orange in color.
Identifying Characteristics
Leaves with markedly wavy margins. This weed may be confused with Broadleaf Dock (Rumex Obtusifolius). However, the much wider and less wavy leaves of broadleaf dock help to distinguish the two species.
Broadleaf Plantain
Weed Description
Perennial from a basal rosette with broad oval leaves. Found throughout the United States, primarily a weed of turfgrass.
Seedlings
Cotyledons are spatula-shaped and joined at the base. Young leaves oval to elliptic with leaves that encircle the stem.
Leaves
Smooth or slightly hairy, oval to elliptic, with a waxy surface and veins that are parallel to the margins. Margins are untoothed and sometimes wavy.
Flowers
Flowers produced on unbranched stalks that arise from the rosette. Flowering stems are 5-15 inches long, clustered with small flowers that have whitish petals and bracts surrounding the flowers.
Fruit
A 2-celled oval capsule, 3-5 mm long, that opens by a lid around the middle.
Roots
Taproot with fibrous roots.
Identifying Characteristics
This weed may be confused with Blackseed Plantain (Plantago Rugelli) that is also found in the eastern United States. Blackseed Plantain has a red or purple coloration at the base of the petioles that is less often found in Broadleaf Plantain. Additionally, the capsules of blackseed plantain are cylindrical and split below the middle, while the capsules of Broadleaf Plantain are egg-shaped and open by splitting around the middle.
Buckhorn Plantain
Weed Description
Perennial weed primarily of turfgrass found throughout the continental United States.
Seedlings
Cotyledons resemble a grass emerging, are linear and smooth.
Leaves
All leaves are in a basal rosette. Leaves are linear to lanceolate (5-25 cm long by 1-2.5 cm wide) with veins running the length of the leaf, may be sparsely hairy or without hairs.
Flowers
A spike that is unbranched and leafless to 10 cm long and contains many inconspicuous flowers.
Fruit
A 2-seeded capsule, 3-4 mm long.
Roots
Fibrous roots from a short taproot.
Identifying Characteristics
Narrow, linear leaves from a basal rosette with characteristic flowering spikes typical of a plantain.
Red Sorrel
Weed Description
A perennial from rhizomes with distinctive arrowhead-shaped leaves and red flowering stems. Red sorrel is primarily a weed of turfgrass, lawns, roadsides, landscapes, and some nursery crops. It is found throughout the United States.
Seedlings
Cotyledons are oblong, without hairs, reaching 10 mm in length. Cotyledons and young leaves usually have a mealy cast on the leaf surfaces. The first true leaf is egg-shaped in outline and occurs on a short petiole. The distinctive arrowhead-shaped leaves develop later.
Leaves
Distinctively arrowhead-shaped due to 2 lobes that occur at the base of the leaves. Most leaves occur in the basal rosette; however, some stem leaves occur also. Basal leaves are approximately 1 to 3 inches long, without hairs (Glabrous), and occur on petioles. Leaves on the flowering stem are arranged alternately and are usually linear in outline (not usually arrowhead-shaped), without distinctive petioles. All leaves have a thin membranous sheath (Ocrea) surrounding the stem at the point of the leaf petiole attachment.
Stems
Flowering stems are erect, reaching 18 inches in height, branching in the upper portions only. Stems are ridged and often maroon-tinted.
Flowers
Occur in clusters on the flowering stems. Flowers can be either yellowish green in color (male) or red to maroon in color (Female).
Fruit
An achene that is also red to maroon in color.
Roots
A taproot and rhizomes.
Identifying Characteristics
The arrowhead-shaped leaves that develop in a basal rosette and the red to maroon-tinged flowering stems are both characteristics that distinguish red sorrel from most other species.
Common Blue Violet
Weed Description
A perennial with heart-shaped leaves and purple flowers, most commonly 2 to 5 inches tall. Common Blue Violet is found throughout the eastern United States and Canada. It is primarily a weed of turfgrass and landscapes.
Leaves
Leaves arise from a basal crown, are heart-shaped, and occur on long petioles. Leaves are also hairless and have rounded teeth along the margins.
Flowers
Occur on stalks that do not contain leaves. Flowers consist of 5 petals that are purple or blue in color. The 2 lateral petals are bearded or hairy near the base.
Fruit
A capsule ranging from 10 to 12 mm in length.
Roots
Rhizomes and a fibrous root system.
Identifying Characteristics
The heart-shaped leaves with rounded teeth along the margins, purple flowers, and rhizomes are all features that help in the identification of Common Blue Violet.
Warm-Season Perennial Broadleaf Weeds
Field Bindweed
Weed Description
A perennial trailing or climbing weed with white morning glory-like flowers that may reach 3 1/3 feet in length. Field Bindweed is primarily a weed of nurseries, agronomic crops, and fencerows that can be found throughout the United States.
Seedlings
Cotyledons are dark green with relatively prominent white- to light green veins. The cotyledons are almost perfectly square, approximately if they are wide, and are slightly indented at the tip.
Leaves
Alternate, occur on petioles, and are triangular in outline. Leaves can occur either without hairs (Glabrous) or can have hairs. The leaf bases are pointed and have lobes that point outward.
Stems
Trail along the ground or climb onto crop plants, fences, etc. Stems may also be either with or without hairs.
Flowers
White to pink in color and approximately 3/4 to 1 inch long. Flowers take on the shape of a funnel and have bracts that are relatively small and separate from the flowers.
Fruit
An oval to round capsule.
Roots
A twisting taproot that extends very deep into the soil serves as the overwintering perennating organ of Field Bindweed.
Identifying Characteristics
Trailing or climbing vine with triangular leaves and lobes that point outward. Additionally, the small bracts that are separate from the flowers of Field Bindweed help to distinguish this from other similar species. Hedge Bindweed (Calystegia Sepium) is similar in appearance and is often mistaken for Field Bindweed, however the leaf bases of hedge Bindweed are cut squarely (Truncate) and this weed also has large bracts beneath the flowers unlike Field Bindweed. Field Bindweed is also often confused with Wild Buckwheat (Polygonum Convolvulus), however Wild Buckwheat has inward-pointing bases and an ocrea at the base of each petiole.
Horsenettle
Weed Description
A perennial from rhizomes with conspicuous spines on the leaves and stems that may reach 3 ft in height. Horsenettle is found throughout the southeastern, eastern, and north-central United States. All parts of the plant, except the mature fruit, are poisonous to livestock even when this weed is consumed in dry hay. However, consumption of this weed rarely occurs due to the prickly stems and leaves.
Seedlings
Cotyledons oblong, glossy green above, light green below with hairs on the margins. Short, stiff hairs cover the hypocotyl, which is often purple-tinged.
Leaves
Simple, elliptic-oblong to oval, alternate, petiole, 2 1/2-4 1/2 inches long and covered on both surfaces with star-shaped hairs. Leaves also emit a potato odor when crushed and contain prominent prickles (6-12 mm long) on the midvein and petiole.
Stems
Angled at the nodes, become woody with age, and also have prickles and star-shaped hairs.
Flowers
Occur in clusters on prickly flower stalks and are star-shaped with 5 white to violet petals and a yellow cone-shaped center, which is actually 5 stamens with yellow anthers.
Fruit
A berry, 1/2-3/4 inches in diameter, green when immature turning yellow and wrinkled with maturity. A single berry may contain from 40 to 120 seeds.
Roots
Deep, spreading rhizomes.
Identifying Characteristics
Stems and leaves with prickles and star-shaped hairs. Horsenettle might be confused with other solanaceous species like Clammy Groundcherry (Physalis Heterophylla). However, groundcherries do not have prickles on the stems and leaves and have papery membranes enclosing their berries.
Yellow Woodsorrel
Weed Description
A perennial with trifoliate leaves and yellow flowers that is primarily a weed in greenhouses, container ornamentals, landscapes, turfgrass, and lawns. Yellow Woodsorrel is found throughout the United States.
Seedlings
Cotyledons smooth, oblong, green. Margins and veins on lower leaf surfaces of young seedlings are sparsely hairy.
Leaves
Arranged alternately along the stem, long-petiolate, and divided into 3 heart-shaped leaflets. Leaf margins are smooth but fringed with hairs.
Stems
Green to pink, weak, branched at base, more prostrate than erect to 20 inches tall, varying from smooth to pubescent.
Flowers
Occur in clusters that arise from long stalks at the leaf axils. Individual flowers consist of 5 yellow petals that are 4 to 9 mm long.
Fruit
A capsule that is cylindrical and pointed with flat sides, sparsely hairy. Each capsule is approximately 3/4 inch long. Seed disperse from capsules by explosively ejecting up to 13 feet from the parent plant.
Roots
Long, slender rhizomes occur with a fibrous root system.
Identifying Characteristics
A weed of greenhouses and ornamentals with leaves that are divided into 3 heart-shaped leaflets with small yellow flowers. Yellow Woodsorrel may be distinguished from Creeping Red Woodsorrel (Oxalis Corniculata) by the presence of underground rhizomes versus the aboveground stolons of creeping red Woodsorrel. Also, Creeping Red Woodsorrel has a more prostrate growth habit and often has more reddish-purple leaves than Yellow Woodsorrel.
