Lepidium

Lepidium L.

(incl. Cardaria Desv., Coronopus Zinn)

Literature: Durand (1899), Thellung (1906), Muschler (1908; Coronopus), Henrard (1916), Hitchcock (1945), Lawalrée (1956), Mulligan (1961), Mulligan & Frankton (1962; Cardaria), Boelcke (1964), Duvigneaud & Lambinon (1975), Jonsell (1975), Ryves (1977), Clement (1981), Hewson (1982), Rich (1988), Vasconcellos (1993), Al-Shehbaz & al. (2002), Lambinon & al. (2004), Al-Shehbaz (2010), Al-Shehbaz & Gaskin (2010), Stace (2010). See also an online contribution by Reichert on http://www.flora-deutschlands.de/Lepidium/bestimmung_der_kleinen_lepidium.htm.

As currently understood and in accordance with recent molecular phylogenetic studies Lepidium is a nearly cosmopolitan genus of ca. 220 species (including Cardaria and Coronopus; see Al-Shehbaz & al. 2002). Only two species, Lepidium campestre L. and L. coronopus (L.) Al-Shehbaz (syn.: Coronopus squamatus (Forssk.) Aschers.), are doubtlessly native in Belgium. Lepidium ruderale L. is usually claimed as a native but it probably is at most an archaeophyte. A fourth species, Lepidium latifolium, has an uncertain residence status in Belgium but is probably not native (compare Durand 1899, Vasconcellos 1993, Lambinon & al. 2004 and Lawalrée 1956).

Several additional species might have been overlooked. Kern & Reichgelt (1938), for instance, drew the attention to Lepidium ramosissimum A. Nelson and L. austrinum Small, two North American species that have been confused with L. densiflorum and L. ruderale respectively in the Netherlands.

1. Inflorescences mostly leaf-opposed racemes. Silicula indehiscent or breaking up in two halves, densely reticulate-ridged or warty. Lower cauline leaves always pinnately lobed. Stems procumbent === 2

1. Inflorescences terminal panicles or racemes. Silicula dehiscent or indehiscent but never breaking up in two halves, smooth or slightly reticulate. Lower cauline leaves entire to pinnately lobed. Stems usually erect, rarely procumbent === 3

2. Silicula distinctly notched at apex, with style not protruding, breaking up in two halves. Seeds 1-2 mm long. Pedicels longer than silicula. Petals shorter than sepals (or absent). Stamens 2 or 4 === Lepidium didymum

2. Silicula rounded at apex, with style protruding, indehiscent. Seeds 2-2,5 mm long. Pedicels shorter than silicula. Petals longer than sepals. Stamens 6 (native) === L. squamatum

3. Silicula indehiscent, cordate ate base, not or hardly compressed. Inflorescence a corymbose panicle. Perennial === L. draba

3. Silicula dehiscent, not cordate at base, laterally compressed. Inflorescence an elongate panicle or raceme. Annual, biennial or perennial === 4

4. Leaves distinctly heterophyllous: the lower 2-3 pinnate, the upper entire and amplexicaul. Petals yellow === L. perfoliatum

4. Leaves slightly heterophyllous to nearly homophyllous, the upper never ovate and amplexicaul. Petals (if present) white, sometimes suffused with red === 5

5. Silicula 4,5-6 mm, style fused with the wings at base. Pedicel shorter than silicula in fruit === 6

5. Silicula < 4 mm long, style free at base. Pedicel longer than silicula in fruit === 8

6. Nearly glabrous, erect annual, often slightly glaucous. Lower cauline leaves usually deeply pinnately lobed === L. sativum

6. Greyish-pubescent decumbent to erect annual, biennial or perennial, never glaucous. Leaves entire === 7

7. Silicula with few to no warty vesicles. Free part of style 0,6-1,2 mm long, distinctly protruding. Perennial === L. heterophyllum

7. Silicula densely covered with warty vesicles. Free part of style ca. 0,5 mm long, not protruding. Annual or biennial (native) === L. campestre

8. Tall glabrous perennial (up to 150 cm tall). Silicula not winged, rounded at apex (not notched), style protruding === L. latifolium

8. Smaller annual or biennial (rarely exceeding 50 cm), slightly hairy or not. Silicula winged, sometimes only narrowly so, always notched at apex === 9

9. All leaves 2 pinnate to pinnately lobed === L. bonariense

9. At least the upper cauline leaves entire or merely toothed === 10

10. Silicula ovate, longer than wide (1,5-2 mm wide). Seeds unwinged. Upper leaves entire. Petals usually absent (native) === L. ruderale

10. Silicula orbicular, nearly as long as wide (2-3,5 mm wide). Seeds winged or not. Upper leaves toothed. Petals usually present, sometimes absent === 11

11. Petals (at least in part) longer than sepals. Stem with elongated, often curved hairs with acute apex. Silicula ca. 3-4 mm long and 2,5-3,5 mm wide === L. virginicum

11. Petals smaller than sepals, sometimes absent. Stem with very short, papillose hairs with obtuse apex. Silicula ca. 2,3-3,5 mm long and 2-3 mm wide === L. densiflorum

Additional aliens: Lepidium africanum (Burm. f.) DC. (syn.: L. divaricatum Soland. subsp. linoides (Thunb.) Thell., L. linoides Thunb.) (S-Afr., wool alien), L. chalepense L. (syn.: L. draba subsp. chalepense (L.) Thell., Cardaria chalepensis (L.) Hand-Mazz., C. draba (L.) Desv. subsp. chalepensis (L.) O.E. Schulz) (SW-As., vector unknown), L. desertorum Eckl. et Zeyh. (S-Afr., wool alien), L. fasciculatum Thell. (Austr., wool alien), L. graminifolium L. (Medit., grain alien), L. hirtum (L.) Smith (Medit., vector unknown) and L. schinzii Thell. (S-Afr., wool alien).

 


Literature

Al-Shehbaz I.A. (2010) A synopsis of the South American Lepidium(Brassicaceae). Darwiniana 48(2): 141-167.

Al-Shehbaz I.A. & Gaskin J.F. (2010) Lepidium. In: Flora of North America Editorial Committee (eds.), Flora of North America, vol. 7. Oxford University Press, New York-Oxford: 570-595.

Al-Shehbaz I.A., Mummenhoff K. & Appel O. (2002) Cardaria, Coronopus, and Stroganowia are united with Lepidium (Brassicaceae). Novon 12: 5-11.

Boelcke O. (1964) Notas sobre especies de Lepidium de la Argentina. Darwiniana 13: 506-528.

Clement E.J. (1981) Aliens and adventives. Adventive news 21. Notes on some alien pepperworts. BSBI News 29: 8-13.

De Lange P.J., Heenan P.B., Houliston G.J., Rolfe J.R. & Mitchell A.D. (2013) New Lepidium (Brassicaceae) from New Zealand. PhytoKeys 24: 1-147. [available online at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3689132/]

Durand T. (1899) Phanérogames. In: De Wildeman E. & Durand T., Prodrome de la flore belge. A. Castaigne Editeur, Bruxelles: 1112 p.

Duvigneaud J. & Lambinon J. (1975) Le groupe de Lepidium ruderale en Belgique et dans quelques régions voisines. Dumortiera 5: 20-26.

Henrard J.Th. (1916) Lepidium. Een systematisch-floristische studie der in Nederland waargenomen soorten en vormen. Nederl. Kruidk. Arch. 1916: 206-247.

Hewson H.J. (1982) The genus Lepidium in Australia. Brunonia 4: 217-308.

Hitchcock C.L. (1945) South American species of Lepidium. Lilloa 11: 75-134.

Jonsell B. (1975) Lepidium L. (Cruciferae) in tropical Africa. Bot. Not. 128: 20-46.

Kern J. & Reichgelt Th. (1938) Twee voor ons land nieuwe Lepidium-soorten. Nederl. Kruidk. Arch. 48: 152-158.

Lambinon J., Delvosalle L., Duvigneaud J. (avec coll. Geerinck D., Lebeau J., Schumacker R. & Vannerom H.) (2004) Nouvelle Flore de la Belgique, du Grand-Duché de Luxembourg, du Nord de la France et des Régions voisines (Ptéridophytes et Spermatophytes). Cinquième édition. Jardin botanique national de Belgique, Meise: CXXX + 1167 p.

Lawalrée A (1956) Cruciferae. In: Robyns W. (ed.), Flore Générale de Belgique, vol. 2, fasc. 2. Jardin Botanique de l’Etat, Bruxelles: 160-285.

Mulligan  G.A. (1961) The genus Lepidium in Canada. Madroño 16: 77-89.

Mulligan G.A. & Frankton C. (1962) Taxonomy of the genus Cardaria with particular reference to the species into North America. Canad. J. Bot. 40: 1411-1425.

Muschler R. (1908) Die Gattung Coronopus (L.) Gaertn. Bot. Jahrb. 41: 111-147.

Rich T.C.G. (1988) Lepidium L. Plant Crib 1988: 25-26.

Rich T. (1988) Cabbage patch 4. Cardaria chalepensis (L.) Handel-Mazzetti in the British Isles. BSBI News 48: 12-14.

Ryves T.B. (1977) Notes on wool-alien species of Lepidium in the British Isles. Watsonia 11: 367-372.

Stace C. (2010) New flora of the British Isles, 3th ed.: XXXII + 1232 p. Cambridge University Press.

Thellung A. (1906) Die Gattung Lepidium (L.) R.Br. Eine monographische Studie.  Neue Denkschr. Schweiz. Naturf. Ges. 41: 1-340.

Vasconcellos J.C. (rev. Akeroyd J.R. & Rich T.C.G.) (1993) Lepidium. In: Tutin T.G. & al. (eds.), Flora Europaea (2nd ed.), vol. 1. Cambridge University Press, Cambridge: 398-402.

Taxonomic name: 
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith