Article
Comparative Taxonomic Study of Launaea Cass. (Asteraceae,
Cichorioideae) in Egypt
Ream I. Marzouk, Salama M. El-Darier, Sania A. Kamal and Iman H. Nour *
Botany and Microbiology Department, Faculty of Science, Alexandria University, Alexandria 21511, Egypt;
Reammarzouk@yahoo.com (R.I.M.); Salama_Eldarier@yahoo.com (S.M.E.-D.); drsaniakamal@gmail.com (S.A.K.)
* Correspondence: Iman.nour@alexu.edu.eg; Tel.: +20-1227854391
Abstract: Launaea is a polymorphic genus with inter- and intraspecific inconsistencies. The study
aimed to revise the classification and identification of Launaea species in Egypt. The study also aimed
to assess the inter- and intraspecific variation among taxa using macro- and micromorphological
characters. Numerical analysis was carried out on 156 specimens, which were collected from
63 sites in Egypt. The results revealed that L. arabica, L. capitata, L. intybacea and L. spinosa were
significantly (p-value < 2.2 × 10−16 *** ) discriminated from the other species at a high dissimilarity
level. Launaea acanthodes was correctly identified as Lactuca orientalis. The study supported the
inclusion of L. intybacea, L. massauensis and L. nudicaulis within section Microrhynchus, the separation of
L. angustifolia and L. arabica in two distinct species. Two biotypes of L. nudicaulis were morphologically
differentiated. Launaea fragilis subsp. fragilis showed considerable plasticity and variability in various
characters; therefore, L. tenuiloba was considered to be merely an ecotype of L. fragilis. Launaea
mucronata comprises two subspecies; cassiniana and mucronata, differentiated by their pappus type,
conspicuous secondary ribs of the inner achenes, and the number of spines on the polar area of
pollen grains.
Citation: Marzouk, R.I.; El-Darier,
S.M.; Kamal, S.A.; Nour, I.H.
Keywords: achenes; asteraceae; Launaea; morphology; pollen grains; SEM
Comparative Taxonomic Study of
Launaea Cass. (Asteraceae,
Cichorioideae) in Egypt. Taxonomy
2021, 1, 192–209. https://doi.org/
10.3390/taxonomy1030014
Academic Editor: Adriano Stinca
Received: 7 June 2021
Accepted: 7 July 2021
Published: 12 July 2021
Publisher’s Note: MDPI stays neutral
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1. Introduction
Asteraceae Martynov is the largest and most diverse family in the Eudicots, with
13 subfamilies and 45 tribes. The family consists of about 1600–1700 genera and
25,000–33,000 species [1]. Currently, Susanna et al. [2] recognized 16 subfamilies and
50 tribes. According to APG IV [3], the family was classified into Eudicots, Superasterids,
Asterids, Campanulids and Asterales. In Egypt, the Asteraceae is represented by 98 genera,
and 234 species are classified into two subfamilies; Liguliflorae and Tubiliflorae. The
former is exemplified by two tribes: Cichorieae Lam. and DC, and Scorzonerinae. The
Cichorieae contains six subtribes; Crepidinae Cass. ex Dumort., Hypochaeridinae Less.,
Hyoseridinae Less., Lactucinae (Cass.) Cass. ex Dumort., Rhagadiolinae Benth. and Hook.f.
and Scolyminae Less. Lactuca L., Launaea Cass., Reichardia Roth and Sonchus L. are grouped
in the subtribe Lactucinae [4,5].
Launaea is a polymorphic genus with inter- and intraspecific inconsistencies, especially
within section Zollikoferia DC. It comprises about 54 species and 10 subspecies and is
classified into eight sections. The genus is distributed into different geographical regions,
particularly Saharo-Arabian, Irano-Taranian and Sudanian S Mediterranean, Africa and
SW Asia [6,7]. Most species have economic, ecological, and ethnobotanical importance
such as anti-inflammatory, antioxidant, anticancer, children fever, soporific, lactagogue,
diuretic, insecticidal, antibacterial and antiparasitic [8–12]. The genus displays considerable
diversity in the Mediterranean and Nile regions of Egypt. According to the Egyptian flora,
Boulos [5] has recorded ten taxa (9 species and 3 subspecies) and classified them into four
sections: Acanthosonchus Shultz Bip., Launaea Cass., Microrhynchus Less. and Zollikoferia [5].
4.0/).
Taxonomy 2021, 1, 192–209. https://doi.org/10.3390/taxonomy1030014
https://www.mdpi.com/journal/taxonomy
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The genus was subjected to various taxonomic demarcations and allocations of its species
in Egypt, which have been summarized in the Supplementary Materials (Table S1).
The current study aimed to review the classification and identification of Launaea
species based on an extensive array of macro- and micromorphological characters. The
study also aimed to assess the inter- and intraspecific variation among taxa.
2. Materials and Methods
2.1. Collection of Specimens
The study was constructed on 156 fresh and herbarium specimens collected from
63 sites to cover the most dominant habitats within the range of the genus distribution in
Egypt (Table S2 and Figure S1). The freshly collected samples were deposited as voucher
specimens at Alexandria University Herbarium (ALEX) and identified according to Kilian [7] and Boulos [5]. The herbarium specimens were loaned from Assiut University
(ASTU), the Cairo Agricultural Research Center (CAIM), Cairo University (CAI) and the National Research Centre (CAIRC). Herbarium acronyms follow The Index Herbariorum [13].
The studied specimens represent 10 taxa of Launaea (L. angustifolia subsp. angustifolia (Desf.)
Kuntze, L. angustifolia subsp. arabica (Boiss.) N. Kilian, L. capitata (Spreng.) Dandy, L. fragilis
subsp. fragilis (Asso) Pau, L. intybacea (Jacq.) Beauverd, L. massauensis (Fres.) Chiov.,
L. mucronata subsp. cassiniana (Jaub. and Spach) N. Kilian, L. mucronata subsp. mucronata
(Forssk.) Muschl., L. nudicaulis (L.) Hook.f. and L. spinosa Sch.Bip.). Reichardia and Launaea
are the most closely related genera within subtribe Hyoseridinae [14]. As a result, the
widely distributed R. tingitana (L.) Pau was used as an outgroup in the cluster analysis.
Photographs of the whole plant materials were illustrated in the Supplementary Materials
(Figures S2–S13).
2.2. Macromorphological Characters and Numerical Analysis
For the vegetative and floral attributes, three replicas were measured for each specimen. Specimens were examined using Olympus stereomicroscope and measured using
ImageJ (1.51J8) [15]. All leaf characters were studied for the rosette leaves, except the leaf
attachment and the auricle margin were studied in the cauline leaves. For the achene
macromorphology, measurements were carried out on nine replicas for each specimen.
The studied achenes were selected from three different positions in the fruiting capitulum,
marginal, submarginal and inner, to investigate the achenes variation. The submarginal
achenes represented a transition state between the marginal and the inner ones; therefore,
their measurements were omitted. The achenes measurements were conducted using
Olympus stereomicroscope supported with 1 cm ocular micrometer. The terminology of
macromorphological characters follows De Vogel [16] Kilian [7], Simpson [17] and Roque
et al. [18].
One hundred and fifty-six specimens were subjected to numerical analysis by using
82 macromorphological characters; 16 vegetative, 37 floral and 29 achene characters. The
complete list of the assessed quantitative and qualitative macromorphological characters
and their states is presented in the Supplementary Materials (Table S3). The agglomerative
cluster analysis was performed through the PAST program for mixed data set [19]. The
dendrogram was constructed by the UPGMA method of sorting based on the Manhattan
dissimilarity coefficient.
2.3. Micromorphological Characters (SEM) and Numerical Analysis
The achene and pollen micromorphological characters were investigated for 17 samples obtained from 17 hypothetical groups. These individuals were selected based on the
cluster analysis resulting from the study of 82 macromorphological characters performed
to assess the inter- and intraspecific variation among taxa. Marginal and inner achenes
were preliminarily examined using a stereomicroscope to ensure that they were of normal
size, shape and maturity. The achenes were mounted directly on stubs using double-sided
adhesive tape and then coated with gold, up to a thickness of 400 A in a sputter-coating
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unit (JFC-1100 E). The samples were examined and photographed with a JEOL JSM-5300
scanning electron microscope. A total of 11 micromorphological attributes were assessed.
The terminology follows Barthlott [20], Simpson [17], Zhang et al. [21] and Hussein and
Eldemerdash [22].
The pollen grains were mounted directly on a glass cover and coated with gold up to
a thickness of 400 A in a sputter-coating unit (JFC-1100 E). An average of ten pollen grains
were examined and photographed for each specimen with a JEOL JSM-5300 scanning
electron microscope. The number of spines on the polar area (excluding ridges), the
ratio of polar area to pollen area and the apocolpium index were investigated. The latter
was calculated according to the following equation: Apocolpium index = (apocolpium
diameter/equatorial diameter) × 100. Fifteen morphological characters were evaluated
according to Punt et al. [23] terminology. The complete list of the assessed quantitative
and qualitative micromorphological characters and their states were presented in the
Supplementary Materials (Table S4).
The cluster analysis was achieved based on 26 micromorphological characters. The
similarity among specimens was determined through the Hamming dissimilarity coefficient, and the dendrogram was constructed by the UPGMA method of sorting by using
the PAST program of Hammer et al. [19]. Also, a Principal Coordinate Analysis (PCoA)
was conducted to visualize similarities and dissimilarities among the 17 groups. The PCoA
was performed by using the R- software (Vienna, Austria), with the required packages
installed [24].
3. Results
3.1. Numerical Analysis of Macromorphological Characters
Eighty-two macromorphological characters were studied for 156 specimens; 18 vegetative and 37 floral traits (Figure 1), and 29 achenes macromorphological traits (Figures 2
and 3). The performed numerical analysis was illustrated in Figure 4.
Reichardia tingitana was segregated at the highest dissimilarity level (1.420), whereas
the taxa of Launaea were divided into four groups representing the four corresponding
sections: Zollikoferia at 1.253, Acanthosonchus at 1.134, and both Launaea and Microrhynchus
at 1.013. A total of 17 hypothetical groups were proposed: R. tingitana, Acanthosonchus
(L. spinosa), Launaea (L. capitata), four groups in Microrhynchus (L. intybacea, L. massauensis
and two forms of L. nudicaulis) and ten groups within Zollikoferia (L. angustifolia subsp.
angustifolia, L. angustifolia subsp. arabica, L. mucronata subsp. mucronata, L. mucronata subsp.
cassiniana and six forms of L. fragilis subsp. fragilis). The morphological distinction between
these groups is summarized in the Supplementary Materials (Table S5).
(a)
(b)
(c)
Figure 1. Cont.
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(d)
(e)
(f)
(g)
(h)
(i)
Figure 1. Stereomicrographs of Launaea leaves and capitula. (a–f) Leaf attachment and auricle margin; (a) Non-auriculated
leaf in L. nudicaulis; (b,c) auriculated with semi-amplexicaul base in L. fragilis subsp. fragilis; (b) entire margin or (c) dentate
margin; (d–f) auriculated with amplexicaul base; (d) entire margin in L. fragilis subsp. fragilis or (e) dentate margin in
L. fragilis subsp. fragilis or (f) dissected margin in L. mucronata subsp. cassiniana. (g–i) Capitulum shape, involucre scale
graduality and ligule color; (g) ellipsoid, non-gradual and yellow ligule; (h) lanceoloid, non-gradual and yellow ligule; (i)
obovoid, gradual and yellow ligule with green abaxial surface. Scale bar = 1 mm.
(a)
(b)
(c)
(d)
(e)
(f)
Figure 2. Cont.
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(g)
(h)
(i)
(j)
(k)
(l)
(m)
(n)
Figure 2. Stereomicrographs of marginal achenes shape (upper), base (lower left) and apex (lower right). (a) Reichardia
tingitana, obcolumnar, truncate base and apex. (b–n) Launaea: (b) L. spinosa, subcuneate, truncate base and apex; (c) L. capitata,
winged-cylindrical, truncate base and apex; (d) L. intybacea and (e) L. massauensis, beaked-subfusiform, truncate base, rostrate
apex; (f) L. nudicaulis, subcuneate, truncate base and apex; (g) L. nudicaulis (specimen 33), subfusiform, truncate base and
apex; (h) L. angustifolia subsp. angustifolia, cylindrical, horned base, truncate apex; (i) L. angustifolia subsp. arabica, cylindrical,
horned base, truncate apex; (j–l) L. fragilis subsp. fragilis: (j) cylindrical (specimens 129) or (k) columnar (specimens 72) or (l)
obcolumnar (specimens 102), horned base, truncate apex; (m,n) L. mucronata: (m) subsp. cassiniana and (n) subsp. mucronata,
columnar, truncate base and apex. Scale bar = 0.5 mm.
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(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
(k)
(l)
(m)
Figure 3. Stereomicrographs of inner achenes shape (upper), truncate base (lower left) and apex (lower right). (a) Reichardia
tingitana, columnar, truncate base and apex. (b–m) Launaea: (b) L. spinosa, columnar, truncate base and apex; (c) L. capitata,
winged-cylindrical, truncate base and apex; (d) L. intybacea, beaked-cylindrical, truncate base, rostrate apex; (e) L. massauensis,
columnar, truncate base, cuspidate apex; (f) L. nudicaulis, cylindrical, truncate base and apex; (g) L. nudicaulis (specimen
33), columnar, truncate base and apex; (h) L. angustifolia subsp. angustifolia, cylindrical, horned base, truncate apex; (i)
L. angustifolia subsp. arabica; columnar, horned base, truncate apex; (j,k) L. fragilis subsp. fragilis: (j) cylindrical (specimens 88)
or (k) columnar (specimens 102), horned base, truncate apex; (l,m) L. mucronata: (l) subsp. cassiniana, (m) subsp. mucronata,
columnar, truncate base, attenuate apex. Scale bar = 0.5 mm.
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Figure 4. Dendrogram using the UPGMA method of sorting for the 156 specimensof Launaea and Reichardia tingitana. 1, R.
–
tingitana; 2, (Ar) L. angustifolia subsp. arabica; 3, (Sp) L. spinosa; 4, (Cp) L. capitata; 5, (In) L. intybacea; 6–7, (Nd) L. nudicaulis;
8, (M) L. massauensis; 9, (An) L. angustifolia subsp. angustifolia;
10, (Fr) L. fragilis subsp. fragilis; 11, (Mm) L. mucronata
–
subsp. mucronata; 12, (Mc) L. mucronata subsp. cassiniana; 10, 13–17, (Fr) L. fragilis subsp. fragilis. Stars indicate the studied
specimens for achene and pollen grain micromorphological attributes.
3.2. Numerical Analysis of Micromorphological Characters (SEM)
The agglomerative cluster analysis of 17 samples based on 26 achenes (Figures 5 and 6)
and pappus characters (Figure 7), and palynological characters (Figure 8) is illustrated in
Figure 9. The highest taxonomic distance of the studied groups was 0.830; at this level, both
R. tingitana and L. angustifolia subsp. arabica were discriminated. At 0.655 dissimilarity
level, Launaea sections were distinguished: Acanthosonchus, Launaea, Microrhynchus and
Zollikoferia. Both Acanthosonchus and Launaea were represented by L. spinosa and L. capitate,
respectively. For section Microrhynchus, two clusters were segregated: “1” and“1”
“2”and
at
“2”
at
0.420.
luster
“1”
aggregated
both
0.420. Cluster “1” aggregated both L. intybacea and L. nudicaulis (group 6), while cluster “2”
cluster “2”
grouped and L. nudicaulis (group 7).
grouped
L. massauensis
Section Zollikoferia was separated into four clusters at 0.50 dissimilarity level. Cluster
“3”comprised
comprisedthe
thetwo
twosubspecies
subspeciesof
ofL. mucronata; cassiniana and mucronata. While, cluster
“3”
“4”aggregated
aggregated groups
groups 13
13 and
and 10
10 of
“4”
of L. fragilis subsp. fragilis, and the other specimens
“5”.
Finally,
cluster
“6”
isolated
of the latter subspecies were assembled belowluster
cluster
“5”.
Finally,
cluster
“6”
isolated
L. angustifolia subsp. angustifolia.
The distinction among the seventeen hypothetical groups is performed also by the
Principle Coordinate Analysis (PCoA) (Figure 10). The first and second axis explained
31.56% and 28% of the variance, respectively, which emphasize a moderate variation for
the data. The taxa representing each section were assembled together. The widest range of
variation was noticed in section Zollikoferia, especially among the taxa of L. fragilis subsp.
fragilis and between the two subspecies of L. angustifolia.
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(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
(k)
(l)
Figure 5. SEM micrographs of marginal achenes. (a) Reichardia tingitana, coarse-verrucate transversely rugose surface.
(b–l) Launaea, wrinkled surface: (b) L. spinosa, short squarrose with rounded apex, elongated adjusted epidermal cells
with long rounded projections; (c) L. capitata, short squarrose with acute apex, elongated adjusted epidermal cells with
short rounded projections; (d) L. intybacea and (e) L. massauensis, long recurved with acute apex, diffused epidermal cells
with long acuminate projections; (f,g) L. nudicaulis (group 6), long incurved or recurved with acute apex, nearly adjusted
elongated epidermal cells with short acute projections; (h) L. nudicaulis (group 7), long squarrose with acute apex, nearly
adjusted elongated epidermal cells with long acuminate projections. (i–l) Launaea, papillose surface: (i) L. angustifolia subsp.
angustifolia, long and linear unconnate papillae; (j) L. angustifolia subsp. arabica, long and linear connate papillae forming
hyaline wing; (k) L. fragilis subsp. fragilis and (l) L. mucronata subsp. cassiniana, short and clavate papillae.
(a)
(b)
(c)
(d)
(e)
(f)
Figure 6. Cont.
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(g)
(h)
(i)
(j)
(k)
(l)
(m)
(n)
Figure 6. SEM micrographs of inner achenes. Epidermal Cell (EC), End Wall (EW), Anticlinal Wall (AW), Relief of Cell
Boundary (RCB), Outer Periclinal Wall (OPW) and Fine Relief of Periclinal Wall (FRPW). (a) Reichardia tingitana, isodiametric
EC, obscure EW, AW and RCB, sparsely tuberculate OPW, nearly smooth FRPW. (b–n) Launaea: (b,c) L. spinosa, elongated
nearly adjusted EC, long antrorse projection of EW, raised straight AW, channelled RCB, concave OPW, nearly smooth
FRPW; (d) L. capitata, isodiametric EC, EW without projection (at the achene wing), raised straight to irregular AW, raised
RCB, concave OPW, nearly smooth FRPW; (e) L. intybacea, elongated adjusted EC, short antrorse projection of EW, raised
straight AW, channelled RCB, concave OPW, nearly smooth FRPW; (f) L. massauensis, elongated nearly adjusted EC, EW
without projection, raised straight AW, raised RCB, concave OPW, nearly smooth FRPW; (g,h) L. nudicaulis: EW without
projection, raised straight AW, raised RCB, concave OPW, nearly smooth FRPW, (g) group 6, elongated adjusted EC, (h)
group 7, elongated nearly adjusted EC; (i) L. angustifolia subsp. angustifolia, diffused EC, long antrorse projection of EW,
raised straight AW, channelled RCB, flat OPW, striate FRPW; (j) L. angustifolia subsp. arabica, obscure EC, EW, AW and
RCB, nearly smooth FRPW, papillose OPW; (k,l) L. fragilis subsp. fragilis, (k) nearly adjusted EC, long antrorse projection of
EW, raised straight AW, channelled RCB, flat OPW, nearly smooth FRPW; (l) diffused EC, short antrorse projection of EW,
raised straight AW, raised RCB, concave OPW, striate FRPW; (m,n) L. mucronata: elongated adjusted EC, raised straight AW,
channelled RCB, flat OPW, striate FRPW, (m) subsp. cassiniana, long antrorse projection of EW, (n) subsp. mucronata, short
antrorse projection of EW.
(a)
(b)
(c)
(d)
(e)
(f)
Figure 7. SEM micrographs of pappus type, protuberance density in 150 µm and orientation. (a) subhomomorphic setaceous
bristles, sparsely, appressed in L. spinosa; (b) dimorphic, sparsely, appressed in L. massauensis; (c) dimorphic, moderate,
appressed in L. nudicaulis (group 7); (d) homomorphic of cottony rays, bristles absent in L. angustifolia subsp. arabica; (e,f),
high, inclined in L. mucronata: (e), subhomomorphic setaceous bristles in L. mucronata subsp. cassiniana, (f), dimorphic in
L. mucronata subsp. mucronata.
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(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
(k)
(l)
(m)
/Figure 8. SEM micrographs of pollen grains for polar view (left), equatorial view (middle) and paraporal ridge ornamentation (right) for each taxon. (a) Reichardia tingitana, spiny-granulate. (b–m) Launaea: (b) L. spinosa, spiny; (c) L. capitata,
spiny-perforate; (d) L. intybacea and (e) L. massauensis, spiny-perforate; (f,g) L. nudicaulis: (f) group 6, spiny-perforate; (g)
group 7, spiny; (h) L. angustifolia subsp. angustifolia, spiny-perforate; (i) L. angustifolia subsp. arabica, spiny; (g–k) L. fragilis
subsp. fragilis, (g), group 13, spiny-granulate, (k), group 17, spiny-perforate; (l) L. mucronata subsp. cassiniana, spiny; (m)
L. mucronata subsp. mucronata, spiny-perforate.
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Figure 9. Dendrogram resulted from the UPGMA method of sorting for seventeen samples representing the outgroup
Reichardia tingitana and 10 taxa of Launaea based on the achene and the pollen grain micromorphological attributes.
Figure 10. Principal Coordinate Analysis (PCoA) of seventeen samples representing the outgroup Reichardia tingitana and
10 taxa of Launaea based on the achene and the pollen grain micromorphological attributes.
202
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4. Discussion
The current study is the first comprehensive taxonomic study on Launaea in Egypt
based on morphological data. R. tingitana was used as an outgroup. The outgroup can
be defined as a more distantly related group of taxa that serves as a reference group
when determining the phenetic relationships of the in-group [25]. According to Kilian
et al. [14], Reichardia and Launaea are the most closely related genera within Hyoseridinae.
The detailed characterization of Launaea sections and the species in each one, as well as the
taxonomic status for each species, will be summarized in the following part.
4.1. Section Acanthosonchus
It is a monospecific section containing L. spinosa, although Zareh et al. [26] have
added L. acanthodes (Boiss.) Kuntze as a new record, based on one herbarium specimen
(kept in ASTU herbarium) from Wadi Telah in Sinai (7.10.1983). In the current study, this
specimen is correctly identified as Lactuca orientalis (Boiss.) Boiss. (Syn. Scariola orientalis
Boiss.), which is characterized by spinescent shrub and woolly-floccose white stems of
green stripes, as well as the sessile heads with up to 5 florets per capitulum and the achene
of 8 main ribs on each face with scabridulous pappus [4,5,27]. That is in agreement with
Kilian [7], as Lactuca orientalis is confusing and similar to L. acanthodes.
4.2. Section Launaea
Osman [28] and Soliman et al. [29] were accepted by only L. capitata in the section.
Launaea procumbens (Roxb.) Ramayya and Rajagopal was added as a very rare species
by Montasir and Hassib [30], Täckholm [4], Kilian [7] and Boulos [5]. The existence of
L. procumbens in Egypt is based on four specimens collected from Wadi Mbaruth (Qoseir),
El-Tor (Sinai), Cairo (Pyramids) and Karnak (Luxor) since 1864, 1880, 1902 and 1926,
respectively [5,7]. Currently, this species is represented by three sterile specimens collected
in 1956 from Wadi Abar (Gebel Ataqa), Wadi Seyal (North Galalah), and Wadi Qiseib
(Suez), which are kept in the CAI Herbarium. Therefore, the current study includes only
L. capitata in section Launaea.
4.3. Section Microrhynchus
Launaeaintybacea, L. massauensis and L. nudicaulis belong to section Microrhynchus.
Launaea intybacea was translocated from Lactuca to Launaea as Launaea fallax or Launaea
goraeensis [4,30]. It is a very rare species, and it was not recorded in the Egyptian collection
of Kilian [7] and Boulos [5]. The present study includes a unique sample deposited in
the CAI Herbarium. The sample was collected from Wadi Laseitit (Halayeb Triangle) by
Täckholm in 1962.
For Launaea massauensis, the results support involving it with L. intybacea and L. nudicaulis
in the same section. This finding corresponds to Kilian [7] for assorting L. massauensis in
Microrhynchus instead of Brachyrrhampus DC, as was classified by Boissier [31].
Launaea nudicaulis is a common polymorphic species in Egypt [4,5,30]. The investigation of the vegetative and floral characters reveals significant variation resulting from
many intermediate forms. The most distinguished characters are the leaf size and shape,
capitulescence type, floret dimensions, achene size, color and the degree of wrinkles that
decrease in the inward direction. The description coincides with the studies of Amin [6],
Kilian [7] and Alavi [32], where the achenes are variable in width, color and degree of
wrinkles and achieve a gradual decrease towards the head center.
Two biotypes are distinguished morphologically: biotype 1 (group 6) and biotype 2
(group 7). For biotype 1, the capitulescence is either divaricate or divaricate with a cluster.
The marginal achenes are subcuneate of 2.05–3.35 × 0.30–0.70 mm, with long incurved or
recurved wrinkles of acute apex, and epidermal cells among wrinkles with short acute
projections. The inner achenes are cylindrical of 2.05–3.40 × 0.25–0.60 mm. They are either
compressed or uncompressed with elongated adjusted epidermal cells. The pappus is
relatively short, of 5.85 to 9.95 mm, and the bristles reveal four different thicknesses with
Taxonomy 2021, 1
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sparse protuberance density. The size of the pollen grains is 13.19–13.99 × 14.28–14.92 µm.
The equatorial ridge varies from 4.89 to 5.56 µm, and the apocolpium diameter from 4.10 to
4.48 µm. The depth of abporal lacunae ranges from 2.31 to 2.71 µm, while that of paraporal
lacuna is 1.97 to 2.50 µm. The paraporal ridge ornamentation is either spiny-perforate or
spiny-granulate, and the number of spinules on the polar area ranges from 13 to 17.
For biotype 2, the capitulescence is divaricated. The marginal achenes are subfusiform
of 2.40–3.90 × 0.30–0.65 mm, with long squarrose wrinkles of acute apex, and long acuminate projections of the epidermal cells among wrinkles. The inner achenes are compressed
and columnar of 2.15–3.30 × 0.30–0.50 mm, and their epidermal cells are elongated nearly
adjusted. The pappus ranges from 7.15 to 10.30 mm, and its bristles possess five different
thicknesses of moderate protuberance density. The size of the pollen grains is 11.74–12.34
× 11.52–13.12 µm, the equatorial ridge is from 5.46 to 5.69 µm, and the apocolpium diameter is from 3.21 to 4.39 µm. The depth of abporal lacunae varies from 2.29 to 2.40 µm,
whereas the depth of paraporal lacuna ranges from 1.97 to 2.04 µm. The paraporal ridge
ornamentation is spiny, and the number of spinules on the polar area ranges from 13 to 15.
The achene macromorphological characters of biotype 2 are congruent with the description
of L. procumbens, mentioned by Alavi [32], Kilian [7], Boulos [5] and Qureshi et al. [33],
excluding the deciduous homomorphic pappus.
Therefore, the present study suggests two biotypes of L. nudicaulis, one of which shares
some macromorphological characters with L. procumbens, such as the subfusiform marginal
achenes, the columnar inner achenes and the dimorphic pappus [34]. Determining the
taxonomic rank of these biotypes requires freshly collected specimens for L. procumbens
and more specialized molecular techniques, such as DNA barcoding, amplified fragment
length polymorphism (AFLP), or microsatellites.
4.4. Section Zollikoferia
According to the Egyptian taxa, the section contained three subgroups: amal-aminiae,
angustifolia and mucronata [7].
In the first subgroup, L. amal-aminiae N.Kilian was recognized by Amin [35] as a
distinct and undescribed species. Kilian [7] identified this species according to its leafless
flowering stems, slender capitula, and the different indumentum of the achenes. This
description was based on five old specimens collected from Sinai, El-Arish, and Wadi
Tundebar in Ras Benass (Red Sea) in 1849, 1855 and 1864, respectively. Besides, two
specimens were collected from Suez since 1886 and 1908. Through personal communication
with Prof. Amal Amin, she clarified that there were two voucher specimens representing
this species, kept at the CAI Herbarium. These two specimens were collected from Suakin
el Qadim, and from Halayeb Triangle. Nowadays, the two specimens no longer exist at the
CAI Herbarium; also Suakin el Qadim became a part of Sudan. As a result, this species
was not involved in the present study. The second subgroup, angustifolia, was represented
in Egypt by L. angustifolia Muschl. with two subspecies: angustifolia and arabica. Launaea
angustifolia subsp. angustifolia was first recorded in Egypt by Zareh et al. [26,36], whereas
Kilian [7] declared that the species is restricted to a small area in NW Africa, and it had not
been found in Egypt. Our study characterizes the subspecies with its papillose marginal
achenes that showed long unconnate papillae in the form of two wings, glabrous inner,
and achenes dimorphic pappus. An extensive field survey must be done to address the
distribution of this species in Egypt.
Following Muschler [37], Montasir and Hassib [30], Täckholm [4] and Boulos [5], the
description of L. angustifolia in Egypt has been applied to the subspecies arabica. Kilian [7]
accepted Launaea arabica (Boiss.) H.Lindb. at the subspecies level; L. angustifolia subsp.
arabica (Boiss.) N.Kilian. Whereas the current study considered L. arabica at the species
level, that is confirmed through the numerical analyses using all types of data, separately
and collectively. Marginal and inner achenes of Launaea arabica display long and linear
connate papillae (hyaline papillae), and homomorphic pappus of cottony rays.
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The third subgroup mucronata comprises both L. fragilis and L. mucronata. The two
species are closely related with relative uniformity and some infraspecific variability [7].
Both taxa were treated as conspecific and were ranked as subspecies or varieties by various
authors [32,38,39].
Launaea fragilis is characterized by their auriculated cauline leaves, semiamplexicaul or
amplexicaul base, and auricle of either entire or dentate margin. The apices of the outer and
middle involucre scales may be acute or acuminate. The inner achenes exhibit conspicuous
secondary ribs, and horned base. The pappus is dimorphic with less than 100 setaceous
bristles of moderate appressed aristate protuberance, while L. mucronata is specified with
auriculated cauline leaves, amplexicaul base, and dissected auricle margin. The apices of
the outer and middle involucre scale are acuminate. The inner achenes show ventricose
truncate base with either conspicuous or inconspicuous secondary ribs. The pappus is
subhomomorphic of setaceous bristles or dimorphic with less than 100 setaceous bristles.
The bristles possess inclined aristate protuberance of high density.
The cluster analysis of the micromorphological characters illustrates the separation of
groups 10 and 13 of L. fragilis subsp. fragilis with L. mucronata. These groups share some
characters, such as the raised straight anticlinal walls of inner achenes, the channelled relief
of cell boundary, and the flat outer periclinal walls with striate fine relief. Also, the ratio of
polar area to pollen area is less than 40%, and the length spines is more than 1 µm. Some
individuals of L. fragilis share characters with L. mucronata, such as the auriculated leaves,
the large capitula, and the ventricose base of the inner achenes. These forms were initiated
due to the hybridization between the two species, as they were sympatric in the Nile Delta
and the Mediterranean coast in Egypt. In these regions, two cytotypes of L. fragilis were
identified, diploid (2n = 16) and tetraploid (2n = 32) [7,29,40].
Launaea fragilis subsp. fragilis has demonstrated considerable plasticity and variability
in many attributes related to its leaf, capitulum size, number of florets, achene and pappus.
These variations were correlated with the ecological amplitude and the wide geographical
distribution of the subspecies. Therefore, several names were published at the specific or
the infraspecific rank, validly or invalidly, such as L. longiloba (Boiss. and Reut.) Maire,
L. resedifolia Druce or L. tenuiloba Muschl. [4,30,41,42].
In Egypt, L. resedifolia was cited as a polymorphic species characterized with linear leaf
lobes, the main ribs of the marginal achene are 5 to 6, and a silky pappus with a length up
to 12 mm [4,6,32]. González [43] accepted the name L. fragilis for L. resedifolia and pointed
out that the basionym of L. resedifolia has belonged to Scorzonera laciniata L. L. longiloba
was ranked as an ecotype for L. fragilis and attributed its vigorous plants to the humidity
and favorable conditions by Kilian [7]. Täckholm [4] and Feinburn-Dothan [44] classified
L. tenuiloba at the species level. They have described this species by its filiform leaves with
entire or dentate lobes, pappus length that is equal to the achene, and its inland distribution.
Zareh et al. [26] allocated L. tenuiloba as a subspecies: L. fragilis subsp. tenuiloba (Boiss.)
Zareh and Mohamed comb. et stat. nov., based on its various leaf lobes, and the pappus
that is longer than the achene.
Our findings discriminate six intermediate forms correlated to the environmental
factors without specific features. Consequently, the current study consents L. longiloba,
L. tenuiloba and the intermediate forms as ecotypes in L. fragilis subsp. fragilis.
Launaea mucronata Muschl. comprised two subspecies: cassiniana and mucronata [5,7].
They were ranked at the species level by Montasir and Hassib [30] and Täckholm [4].
However, Alavi [32] accepted this species as a variety of L. resedifolia. In light of the studied
macro- and micromorphological attributes, the subspecies level is accepted; L. mucronata
subsp. cassiniana and L. mucronata subsp. mucronata.
Launaea mucronata subsp. cassiniana has lanceolate rosette leaves, and the capitulum
(5.70–5.90 × 4.20–5.03 mm) contains about 51 to 56 yellow florets. The compressed inner
achenes have inconspicuous secondary ribs, and the epidermal cells have long antrorse
projections. The pappus is easily removed and subhomomorphic with the setaceous bristles
ranges from 20 to 30 and exhibits three different thicknesses. However, many authors
Taxonomy 2021, 1
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have pointed out the presence of homomorphic pappus rather than the subhomomorphic
type [4,5,31,45]. The pollen grain ornamentation on the paraporal ridge is spiny, and the
number of spines on the polar area ranges from 3 to 5.
Launaea mucronata subsp. mucronata possesses oblong to lanceolate rosette leaves, and
the capitulum (9.64–17.15 × 4.06–10.26 mm) encloses about 35 to 60 yellow florets. The
florets have a green abaxial surface. The inner achenes are uncompressed with conspicuous
secondary ribs, and the epidermal cells have short antrorse projections. The pappus is
dimorphic and made of up to 40 setaceous bristles with five different thicknesses. Although,
Täckholm [4], Amin [6] and Boulos [5] had recorded only 12 to 13 bristles. The pollen
grains display a spiny-perforate paraporal ridge, and the number of spines is about 10
to 14 spines on the polar area, the number of spines counted by Osman [28] for the two
subspecies agrees with the present study.
The current study proposes a dichotomous indented key for the discrimination and
identification often taxa of Launaea based on macro- and micromorphological characters.
1.
1.
2.
2.
3.
3.
4.
4.
5.
5.
6.
6.
7.
7.
8.
8.
Spinescent branches; early deciduous cauline and rosette leaves, leaf lobes 4; achenes
subhomomorphic, inner achene with 5 main ribs . . . . . . . . . . . . . . . . . . . . . L. spinosa
Spineless branches; persistent rosette leaves, leaf lobes more than 5; achenes
heteromorphic, inner achene with 4 main ribs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2
Leaf fragile; marginal achene apex rostrate and beaked . . . . . . . . . . . . . . . . . . . . . . . . 3
Leaf normal; marginal achene apex truncate and not beaked . . . . . . . . . . . . . . . . . . ... 4
Leaf lobe shape ovate; capitulescence divaricate; capitulum width less than 2 mm; inner
achene shape columnar and creamy white with apex cuspidate . . . ... L. massauensis
Leaf lobe shape oblong; capitulescence virgate; capitulum width more than 2.5 mm;
inner achene shape cylindrical and straw with apex rostrate . . . . . . . . . ...L. intybacea
Capitulescence glomerate; ligule whitish-yellow; winged achenes, pappus deciduous
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L. capitata
Capitulescence diffused, divaricate, or divaricate with cluster; ligule yellow;
unwinged achenes, pappus persistent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 5
Cauline leaves non-auriculated, rosette leaves runcinate; involucre scales not gradual
in length, capitulum shape ellipsoid or lanceoloid; marginal achene shape subcuneate
or subfusiform with wrinkled surface, inner achene creamy white . . . ... L. nudicaulis
Cauline leaves auriculated, rosette leaves spathulate; involucre scales gradual in
length; capitulum shape obovoid; marginal achene cylindrical or columnar or
obcolumnar with papillose surface, inner achene brown . . . . . . . . . . . . . . . . . . . . . ...6
Rosette leaf lobed, leaf lobe shape ovate; peduncle length less than 1 cm; marginal
achene length (2.37–2.5 mm), inner achene length (2.56–2.73 mm), marginal and inner
achenes papillose with long and linear connate papillae (hyaline papillae), pappus
homomorphic of cottony rays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... L. arabica
Rosette leaf partite or dissected, leaf lobe shape oblong to linear; peduncle length
more than 1.5 cm; marginal achene length (3.20–7.73 mm), inner achene length
(3.47–8.40 mm), marginal achenes only papillose with short and clavate or long
and linear unconnate papillae, pappus dimorphic or subhomomorphic of setaceous
bristles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...7
Ligule shape linear; marginal achenes with long and linear unconnate papillae; polar
area to pollen area ratio >40%, spinules number on polar area from 16 to 20 . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...L. angustifolia
Ligule shape oblong to linear-lanceolate; marginal achenes with short and clavate
papillae; polar area to pollen area ratio <40%, spinules or spines number on polar area
from 3 to 14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 8
Auricle margin entire or dentate; inner achene with conspicuous secondary ribs and
4-horned (toothed) base . . . . . . . . . . . . . . . . . . . . . . . . . . . ... L. fragilis subsp. fragilis
Auricle margin dissected; inner achene with conspicuous or inconspicuous secondary
ribs and ventricose truncate base . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 9
Taxonomy 2021, 1
207
9.
9.
Ligule yellow with green abaxial surface; marginal achene length (2.95–4.0 mm),
marginal achene length to width from 5.1 to 7.0, inner achene length (3.40–4.60 mm),
inner achene uncompressed with conspicuous secondary ribs, pappus dimorphic;
spines number on polar area from 10 to 14 . . . . . . . . . L. mucronata subsp. mucronata
Ligule yellow; marginal achene length (4.10–4.65 mm), marginal achene length to
width from 9.5 to 13, inner achene length (5.10–5.60 mm), inner achene compressed
with inconspicuous secondary ribs, pappus subhomomorphic of setaceous bristles;
spines number on polar area from 3 to 5 . . . . . . . . . L. mucronata subsp. cassiniana
5. Conclusions
The combined investigations of the macro-and micromorphological traits are used
to revise the classification of ten taxa of Launaea and to assess the inter- and intraspecific
variation among taxa. The authors suggest the following points: (1) The taxonomic rank
of Launaea angustifolia subsp. arabica must be raised to the species level. It is identified in
the present study as Launaea arabica. (2) The elimination of L. acanthodes from the Egyptian
flora, as it is identified correctly as Lactuca orientalis (Syn. Scariola orientalis). (3) Two
biotypes of L. nudicaulis are distinguished morphologically. One of them shares some
macromorphological characters with L. procumbens. Launaea procumbens needs further
morphological and molecular investigations using freshly collected materials. (4) Launaea
fragilis subsp. fragilis displays considerable plasticity and variability in various characters
with intermediate forms, so they are considered ecotypes.
Supplementary Materials: The following are available online at https://www.mdpi.com/article/
10.3390/taxonomy1030014/s1, Table S1: Classification of the Egyptian Launaea Cass. (1912–2016),
Table S2: Taxa of Launaea Cass. and Reichardia tingitana L. Pau collected from 63 sites, Table S3: List of
macromorphological characters and their character states recorded for the 156 specimens of Launaea
Cass. and Reichardia tingitana L. Pau., Table S4: List of micromorphological characters and their
character states recorded for the 156 specimens of Launaea Cass. and Reichardia tingitana L. Pau.,
Table S5: The characteristic features of seventeen hypothetical groups discriminated macromorphologically. Figure S1: Map of Egypt indicating the localities of the 63 sampling sites (Google Earth
Pro 7.1.2.2041). Figure S2: Reichardia tingitana deposited in ALEX Herbarium. Figure S3: Lactuca
orientalis (Syn. Scariola orientalis) deposited in ASTU Herbarium. Figure S4: Launaea spinosa deposited
in CAI herbaria. Figure S5: Launaea capitata deposited in ALEX herbaria. Figure S6: Launaea intybacea
deposited in CAI herbarium. Figure S7: Launaea massauensis deposited in CAI herbarium. Figure S8:
Launaea nudicaulis deposited in ALEX herbarium. Figure S9: Launaea angustifolia subsp. angustifolia
deposited in ASTU herbarium. Figure S10: Launaea arabica deposited in CAIM herbarium. Figure S11:
Launaea fragilis subsp. fragilis deposited in ALEX herbarium. Figure S12: Launaea mucronata subsp.
cassiniana deposited in CAIRC herbarium. Figure S13: Launaea mucronata subsp. mucronata deposited
in CAIRC herbarium.
Author Contributions: Conceptualization, R.I.M.; methodology, R.I.M. and I.H.N.; validation, R.I.M.,
S.M.E.-D., S.A.K. and I.H.N.; formal analysis, I.H.N.; investigation, I.H.N.; Funding acquisition:
I.H.N.; resources, I.H.N.; data curation, I.H.N.; Visualization: R.I.M. and I.H.N.; writing—original
draft preparation, I.H.N.; writing—review and editing, R.I.M., S.M.E.-D., S.A.K. and I.H.N.; supervision, R.I.M., S.M.E.-D. and S.A.K. All authors have read and agreed to the published version of the
manuscript.
Funding: This research received no external funding.
Data Availability Statement: The data presented in this study are available in this article and the
Supplementary Material.
Acknowledgments: We acknowledge Mahmoud S. Abdelhafez, Ecological Researcher, Elba Protected
Area, Natural Conservation Sector, Egyptian Environmental Affairs Agency.Also, we sincerely thank
Moatamad M. Tawfik, the technical operator of the Scanning Electron Microscope Unit, Faculty of
Science, Alexandria University, Alexandria, Egypt.
Conflicts of Interest: The authors declare no conflict of interest.
Taxonomy 2021, 1
208
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