Dysphania ambrosioides (L.) Mosyakin & Clemants

Global description
 
Dysphania ambrosioides is an herb with a strong unpleasant odor. It can reach 40 to 100 cm high. It is green in colour, sometimes tinged with purple. The stems are slightly pubescent. The leaves are oval or elliptical in shape, pointed at the top, attenuated at the base. The edge is generally very irregularly serrated. The upper side is glabrous and the underside is dotted with small transparent yellow glands. The inflorescence is composed of small greenish glomeruli, 0.5 to 1.5 mm in diameter, grouped in spikes along the terminal branches. The seeds, 0.5 to 1.5 mm in diameter, are lenticular glossy, brown to blackish in colour.
 
Cotyledons
 
The cotyledons are elliptical, green in colour on the upper side and reddish on the underside. They are covered with glandular white dots.
 
First leaves
 
The first two leaves are opposite, the following are alternate. The stem elongates after a rosette of 10 to 20 leaves are formed. The seedling releases a strong, unpleasant odor to the touch.
 
General habit
 
Erect herbaceous plant, branched, reaching 1.20 m high, with pyramid growth habit. It is covered with short, fine hairs or almost glabrous and has a large important leaf polymorphism. It gives off a strong pungent odor.
 
Underground system
 
The root is a branched taproot.
 
Stem
 
The stem is erect, branched from the base, particularly when the plant is isolated. The branches are distributed regularly and decrease in size towards the end of the plant, resulting in a pyramidal growth habit. The stem is cylindrical, full, finely pubescent, with white vesicular hair. It is covered with green streaks and may have a purple pigmentation.
 
Leaf
 
The leaves are simple, alternate, shortly-stalked. The leaf blade is closely oval or elliptical, acute at the apex, attenuated with an acute corner at the base. It is 2.5 to 14 cm long and 1.5 to 3.5 cm wide. The margin is normally sinuous to serrated, but can also be irregularly serrated. The venations are protruding on the underside. The upper side is glabrous, of a bright green while the underside is lighter, dotted with small yellow transparent sessile glands, filled with a liquid whose smell is unpleasant
 
Inflorescence
 
The inflorescence is large, and highly branched. The flowers are greenish in colour, 0.5 to 1.5 mm in diameter, grouped by 4 or 5 to form small sessile glomeruli. The latter are gathered in spikes along the terminal branches. Every little spike is underpinned by a small lanceolate leaf bracts.
 
Flower
 
Female flowers have 3 to 5 tepals while bisexual flowers have 4 to 5. They are pubescent to glabrous, glandular, smooth or very rarely keeled. The sepals can be more or less fused. The stamens occur in 4 or 5 but abortions can reduce this number. The ovary is globular
 
Fruit

The fruit is a lenticular indehiscent utricle. It has a glabrous pericarp, wrapped by tepals. It contains only one seed
 
Seed
 
The seed is of lenticular shape, dark reddish brown to blackish in color, 0.5 to 1.5 mm in diameter. It is shiny, with an almost smooth integument, marked with sinuous lines.

Origin

Dysphania ambrosioides is native to Central and South America.

Worldwide distribution

This species is now present in North America, Africa, Europe, Asia and Oceania in tropical and temperate conditions.

https://www.gbif.org/species/5568446