Taraxacum collinum, DC

Kirschner, Jan & Štěpánek, Jan, 2023, A taxonomic revision of Taraxacum sect. Dissecta, a continental steppe group common in Siberia and adjacent regions of Central Asia, Phytotaxa 590 (1), pp. 1921-1935 : 1921-1935

The problematic interpretation of the name Taraxacum collinum

One of the most frequently used names referred to Taraxacum sect. Dissecta is T. collinum DC. As regards its interpretation, the situation is seemingly favourable: the original material is rich and well preserved, it is in good agreement with the protologue, the name appears with detailed descriptions in the relevant literature. However, a closer examination of these sources reveals a less optimistic picture.

Taraxacum collinum in the literature

In the first instance, Leontodon collinus Turczaninow appeared in a paper edited by Besser that included a checklist of plants in the Baikal Lake region provided by Turczaninow ( Besser 1834: 18). Leontodon collinus was not published validly at that place, as it was a nomen nudum (Art. 38.1 of the ICN, Turland et al. 2018). In the early 1830’s, Turczaninow distributed duplicates of his collections to prominent contemporary botanists, and it was Candolle (1838) who used the epithet collinus and published the name T. collinum . Then the latter name appeared in Turczaninow (1842). However, two works, important for the Taraxacum taxonomy, did not accept T. collinum ( Ledebour 1846, Handel-Mazzetti 1907), the former having included it in a rather unclear T. caucasicum , the latter in Taraxacum dissectum . As a consequence, the name T. collinum was seldom used in the literature of the second half of the 19 th, and the first decades of the 20 th centuries. It was B. K. Schischkin who restarted the study of Taraxacum in the Soviet Union in the 1930’s. He adopted T. collinum in Krylov (1949) and provided a detailed description (it was the first time when the flower colour was given as whitish). Schischkin (1964, with a substantial contribution of N. N. Tzvelev) also included T. collinum , with a more detailed description principally based on the previous one. Since then, the name T. collinum appeared in many important floras and checklists ( Tzvelev 1987, Krasnikov 1997 etc.).

The protologue

The majority of characters listed in the protologue ( Fig. 32 ) are taxonomically relevant in modern terms. Mature leaves subglabrous, scape subequalling leaves, distally arachnoid, phyllaries not corniculate, outer ones ovate-lanceolate, appressed, with ± ciliate margin, and achenes spinulose above, much shorter than beak, these are the main features. Implicitly, basing on the comparison with the diagnoses of other taxa included in the Prodromus , the achene colour is unclear, either light greyish or somehow reddish (see the specimen 4a), and the border to the outer phyllaries probably is narrow and inconspicuous. The flower colour, on the same basis, is “standard”, i.e. yellow. There are two varieties, the nominate one (without the explicit recognition) with ± runcinate leaves, the other one, T. collinum var. integrifolium Candolle (1838: 149) , with undivided leaves.

For the nominate variety, the following syntype references are given:

1, “in collibus siccis Dahuriae”

2. “insulis fl. Lena”

For T. collinum var. integrifolium , there are two syntypes referred to:

3. “ad Ochotsk”

4. “in ins. Augera [sic!, meaning Angara] legit cl. Turczaninow”.

In both cases, Candolle stated he had seen herbarium specimens “(v. s.)”, i. e. vidi specimina. The reference to Leontodon salinus auct. (Ledebour) is not considered here because Candolle himself listed it with doubts.

Original material

The specimens cited in the protologue were all found in the De Candolle herbarium (G-DC) in Geneva, Switzerland, and they represent syntypes. They were invariably collected by Turczaninow and annotated as “ Leontodon collinus mihi”, usually with a locality data, sometimes without it. In addition, there are important sets of duplicates distributed by Turczaninow to other botanists, here considered as isosyntypes. The following list of specimens may be compiled :

1. “in collibus siccis” [Dahuriae]

a. G-DC, no. det. 18913 “in collibus siccis ubique”, 1828, (M. [= misit] Turczaninow a Irkoutsk 1830), two slightly different plants

b, c, d, e. G-DC, no. det. 18913 (plants stored in an envelope attached to this herbarium sheet)

f. LE, no. det. 6093 “in siccis prope Ircutiam et cetera 1830”, received from Turczaninow under the name Leontodon collinus by C. A. Meyer in 1838

g. LE, no. det. 6094 “in collibus siccis 1833, Turcz.”, as Leontodon collinus mihi, annotated by N. Tzvelev as “Isotypus! vel Typus!” in 1985.

h. MW, no. det. 20479 “ Leontodon collinus Turcz., Ircutia 1833 ”

i. G, no. det. 18934 “Ircut. M. Turczaninow” [transcribed label], this specimen reached the herbarium G in 1909.

j. P 00691594, photo vid.! “ Ircutia, in collibus siccis 1828, Turcz.”, ded. [=dedit] Turczaninow 1840.

k. K! “ Ircutia, 1830 [Turczaninow]”

l. K! “In siccis prope Ircutiam atc., 1829 [Turczaninow]”

2. “fl. Lena”

a. G-DC, no. det. 18913 “Ad Lenam”, 1835, as Leontodon collinus mihi, m. Turczaninow in 1836

3. “ad Ochotsk”

a. G-DC [sine no. det.] Ochotsk, 1835 (M. [=misit] Turczaninow 1836 [a plant without scapes])

4. “in ins. Augera” [= Angara]

a. G-DC, no. det. 18914 “In insula Angarae ex adverso fabricae Telmensis”, 1830, Turcz. (M. [= misit] Turczaninow 1833] – the only plant with (unripe) achenes in the whole original material. A candidate to become the lectotype of T. collinum var. integrifolium . The locality is situated near the village of Tel’ma (where formerly a glass factory was situated) down the river N. of Irkutsk (approximately at 52°42’26”N, 103°44’57”E).

b. P 691588 (photo!) “In insulis Angarae”, 1829, Turcz. (sent by Turczaninow to Schultz-Bip. in 1840). A single plant with shallowly lobed to undivided leaves, corresponding to T. collinum var. integrifolium .

5. G-DC [sine no. det.] A specimen in G-DC, preserved in a separate envelope under the name “ Leontodon collinus Turcz. !” but without any label.

Characterization of individual forms

The original material of T. collinum var. collinum is represented by small, even dwarf, plants in the stage of early flowering. They share ± appressed, narrowly, indistinctly bordered outer phyllaries, subglabrous leaves, and sparsely arachnoid scapes, often overtopping inflorescence. Unfortunately, they also share the absence of achenes (De Candolle himself did not see any achenes of his var. collinum , and the protologue description of achenes probably is derived from the plants of his T. collinum var. integrifolium (syntype 4a in the above survey). They probably almost all (with the exception of the syntype 1e, see above) belong to T. sect. Dissecta . On the other hand, the plants belonging to the original material considerably vary in taxonomically relevant characters, such as the shape of outer phyllaries, presence / absence of pollen, stigma colour and leaf shape, to an extent indicating that more than one agamospermous taxon is involved. The following Table 2 gives a survey of morphological forms ascertained in the original material. They may or may not represent separate taxa.

Possible interpretation

The main problem of the original material is the fact that none of the above five forms can be defined by means of all character complexes relevant in the Taraxacum taxonomy (flower characters, vegetative traits, outer phyllaries and achenes). In particular, the absence of achenes, very variable within T. sect. Dissecta , makes any interpretation difficult.

The most common form among the syntypes (II), characterized by ovate-lanceolate outer phyllaries with a narrow border, pale stigmas and the probable absence of pollen, is otherwise absent from the material evaluated in the present revision.

Figures

FIGURE 32. The protologue of the name Taraxacum collinum Candolle (1838: 149).

Tables

TABLE 2. Analysis of the original material of the name Taraxacum collinum. The OM specimen numbering corresponds to the list above.

Form	Leaves	Outer phyllaries	Pollen	Stigmas	Element of the OM
I	lateral segments acute, ± narrow, hamate-recurved	narrowly lanceolate to lanceolate	Present, irregular	Greenish to greyish- green	1f, 1b
II	lateral segments hamate- recurved to ± patent, subobtuse	ovate-lanceolate, numerous	Probably absent	light greenish yellow to almost yellow	1c (?), 1g, 1j, 1h2, 5
III	lateral segments very narrow, ± patent	narrowly lanceolate, with border more distinct	Not seen (damaged)	Not seen (damaged)	1d (?), 2a
IV	lateral segments conspicuously recurved to hamate-recurved	narrowly lanceolate to lanceolate	Pollen abundant, irregular	Greenish	1a 1, 1h1, 1i, 4a (?)
V	lateral segments hamate- recurved, ± acute	narrowly lanceolate to lanceolate, loosely appressed	Pollen absent	Greenish	1a 2