Lepidium

Yellow peppercress Lepidium flavum, copyright Jim Morefield.

Belongs within: Brassicaceae.

Lepidium, pepperworts, is a cosmopolitan genus of herbs and shrubs bearing fruits as flattened capsules containing a single seed per chamber (Hickman 1993).

Scurvy and cress
Published 6 March 2017

Without the subject of today’s post, it’s just possible that my home country of New Zealand could have had quite a different history. Sometimes, one shouldn’t overlook the importance of cress.

Pepperwort Lepidium heterophyllum, copyright Anne Burgess.

Lepidium is a genus of herbs and subshrubs belonging to the Brassicaceae, the same family as cabbages, radishes and cauliflowers. The genus is found worldwide, and more than 150 species have been recognised to date. The fruit is a type of dry capsule called a silicle which is usually dehiscent (one subgroup of Lepidium, previously separated as the genus Cardaria, has indehiscent fruit), with strongly keeled or winged valves, and contains a single pendulous seed in each locule. The seeds are usually copiously covered in mucilage (Mummenhoff et al. 2001). Like other members of the Brassicaceae, Lepidium has not been overlooked for culinary uses. Leaves and stems of number of species in the genus, such as garden cress Lepidium sativum and dittander Lepidium latifolium, are used as pot or salad herbs. A South American species, maca Lepidium meyenii, is grown as a root vegetable.

Because of its wide distribution, some early authors suggested that Lepidium was a very ancient genus whose members had diverged with the break-up of the Mesozoic supercontinents. However, more recent phylogenetic analyses (Mummenhoff et al. 2001) have suggested just the opposite: the crown group of Lepidium may have originated in the Mediterranean-Central Asian region little more than two million years ago. The mucilaginous seeds of many species become sticky when damp, and can easily be carried long distances adhered to birds’ feet and other such dispersal agents. Perhaps the most dramatic suggestion of intercontinental dispersal in the genus involves a clade of species found in Australia and New Zealand that phylogenetic analysis suggests originated via hybridisation between two divergent species—with one parent being native to South Africa and the other to California (Mummenhoff et al. 2004).

Cook’s scurvy grass Lepidium oleraceum, copyright Andrea Brandon.

It was one of the members of the latter clade that played a small but significant role in New Zealand history. Lepidium oleraceum is an endemic New Zealand species that was once found growing over much of the country. It is commonly known as ‘Cook’s scurvy grass’, because Captain James Cook was able to collect it while surveying New Zealand to provide vitamin C to stave off the scurvy that could have otherwise devastated his crew. Sadly, this once common plant is now extremely rare: the disappearance of mainland-nesting seabirds means that they are no longer around to provide the guano-enriched soils on which this plant thrived. It also proved extremely palatable to introduced herbivores. As a result, Cook’s scurvy grass is now almost exclusively found on small offshore islets.

Systematics of Lepidium

Characters (from Hickman 1993): Annual to shrub; hairs absent or simple. Basal leaves not rosetted, generally petioled, entire to pinnately lobed; cauline leaves short-petioled to sessile, sometimes clasping or surrounding stem. Flowers small; sepals erect or spreading, oblong to ovate, shed early or persistent; petals linear to obovate, generally white, rarely yellowish, sometimes bristle-like or absent; stamens 6, 4, or 2. Fruit dehiscent, oblong to elliptic or obcordate, flat perpendicular to septum; pedicel cylindric or flat, winged or not. Seeds 1 per chamber, gelatinous when wetted; wing narrow or absent; embryonic root at back of one cotyledon, rarely at edges of both.

<==Lepidium Linnaeus 1753A61
    |--L. africanumGK00
    |--L. apetalumO88
    |--L. aschersoniiH90
    |--L. banksii Kirk 1899 [incl. L. banksii var. ovatum Kirk 1899]A61
    |--L. bidentatum [incl. L. bidentoides]SJP60
    |--L. bipinnatifidumD03
    |--L. biplicatumK90
    |--L. bonarienseH90
    |--L. campestreC55
    |--L. capitatumO88
    |--L. densiflorumH93
    |    |--L. d. var. densiflorumH93
    |    |--L. d. var. elongatumH93
    |    |--L. d. var. macrocarpumH93
    |    |--L. d. var. pubicarpumH93
    |    `--L. d. var. ramosumH93
    |--L. dictyotumH93
    |    |--L. d. var. dictyotumH93
    |    `--L. d. var. acutidens [=L. oxycarpum var. acutidens]H93
    |--L. didymumK10
    |--L. drabaC55
    |--L. fasciculatumH90
    |--L. flavumH93
    |    |--L. f. var. flavumH93
    |    `--L. f. var. felipenseH93
    |--L. flexicaule Kirk 1882 (see below for synonymy)A61
    |--L. foliosumG60
    |--L. fremontiiH93
    |    |--L. f. var. fremontiiH93
    |    `--L. f. var. stipitatumH93
    |--L. graminifoliumH91
    |--L. heterophyllumH93
    |--L. hirtum [incl. L. smithii]C06
    |--L. hypenantionH90
    |--L. hyssopifoliumH90
    |--L. jarediiH93
    |--L. kawarau Petrie 1885 (see below for synonymy)A61
    |--L. kirkii Petrie 1890A61
    |--L. lasiocarpumH93
    |--L. latifoliumC55
    |--L. latipesH93
    |    |--L. l. var. latipesH93
    |    `--L. l. var. heckardiiH93
    |--L. leptopetalumH90
    |--L. linifoliumK90
    |--L. lyratogyrumKM08
    |--L. matau Petrie 1887 (see below for synonymy)A61
    |--L. meyeniiW92
    |--L. monoplocoidesH90
    |--L. montanumH93
    |    |--L. m. var. montanumH93
    |    |--L. m. var. canescensH93
    |    `--L. m. var. cinereumH93
    |--L. muelleri-ferdinandiH90
    |--L. naufragorumNL98
    |--L. nitidumH93
    |    |--L. n. var. nitidumH93
    |    |--L. n. var. howelliiH93
    |    `--L. n. var. oreganumH93
    |--L. oblongumH93
    |    |--L. o. var. oblongumH93
    |    `--L. o. var. insulareH93
    |--L. obtusatum Kirk 1892A61
    |--L. oleraceum Forst. f. 1786 (see below for synonymy)A61
    |--L. oxycarpumH93
    |--L. oxytrichumH90
    |--L. papillosumH90
    |--L. peregrinumH90
    |--L. perfoliatumH93
    |--L. phlebopetalumH09
    |--L. pinnatifidumH93
    |--L. platypetalumK90
    |--L. pseudohyssopifoliumH90
    |--L. pseudopapillosumH90
    |--L. pseudotasmanicumH90
    |--L. puberulumKM08
    |--L. ramosissimumH93
    |    |--L. r. var. ramosissimumH93
    |    `--L. r. var. bourgeauanum [=L. densiflorum var. borgeauanum]H93
    |--L. rotundumG04
    |--L. ruderaleC06
    |--L. sagittulatumH90
    |--L. sativumPT01
    |--L. sisymbrioides Hook. f. 1864 (see below for synonymy)A61
    |--L. strictumH93
    |--L. tenuicaule Kirk 1882 (see below for synonymy)A61
    |--L. thurberiH93
    `--L. virginicumACW01
         |--L. v. var. virginicumH93
         |--L. v. var. mediumH93
         |--L. v. var. pubescensH93
         `--L. v. var. robinsoniiH93

Lepidium flexicaule Kirk 1882 [incl. L. incisum Banks & Sol. ex Hook. f. 1853 non Roth 1802, Nasturtium neozelandicum Kuntze 1891]A61

Lepidium kawarau Petrie 1885 [=L. sisymbrioides ssp. kawarau (Petrie) Thellung 1906; incl. L. kawarau var. dubium Kirk 1899, L. sisymbrioides var. dubium (Kirk) Thellung 1906]A61

Lepidium matau Petrie 1887 [=L. sisymbrioides ssp. matau (Petrie) Thellung 1906; incl. L. sisymbrioides ssp. matau var. lobulatum Thellung 1906]A61

Lepidium oleraceum Forst. f. 1786 [=Thlaspi oleraceum Poir. 1806, Nasturtium oleraceum Kuntze 1891; incl. Lepidium oleraceum var. acutidentatum Kirk 1899, L. oleraceum var. frondosum Kirk 1899, L. oleraceum var. serrulatum Thellung 1906]A61

Lepidium sisymbrioides Hook. f. 1864 [=Nasturtium sisymbrioides Kuntze 1891; incl. L. sisymbrioides ssp. solandri var. ovatum Thellung 1906 non L. banksii var. ovatum Kirk 1899, L. solandri Kirk 1882, L. sisymbrioides ssp. solandri (Kirk) Thellung 1906, L. sisymbrioides ssp. solandri var. typicum Thellung 1906]A61

Lepidium tenuicaule Kirk 1882 [incl. L. australe Kirk 1882, L. tenuicaule var. australe (Kirk) Kirk 1899, L. tenuicaule var. minor Cheeseman 1911]A61

*Type species of generic name indicated

References

[ACW01] Aguilar, H., C. C. Childers & W. C. Welbourn. 2001. Relative abundance and seasonal occurrence of mites in the family Tydeidae on citrus in Florida. In: Halliday, R. B., D. E. Walter, H. C. Proctor, R. A. Norton & M. J. Colloff (eds) Acarology: Proceedings of the 10th International Congress pp. 376–380. CSIRO Publishing: Melbourne.

[A61] Allan, H. H. 1961. Flora of New Zealand vol. 1. Indigenous Tracheophyta: Psilopsida, Lycopsida, Filicopsida, Gymnospermae, Dicotyledones. R. E. Owen, Government Printer: Wellington (New Zealand).

[C55] Candolle, A. de. 1855. Géographie Botanique Raisonée: Ou exposition des faits principaux et des lois concernant la distribution géographique des plantes de l’époque actuelle vol. 2. Librairie de Victor Masson: Paris.

[C06] Cheeseman, T. F. 1906. Manual of the New Zealand Flora. John Mackay, Government Printer: Wellington.

[D03] Dusén, P. 1903. The vegetation of western Patagonia. In: Scott, W. B. (ed.) Reports of the Princeton University Expeditions to Patagonia, 1896–1899 vol. 8. Botany pp. 1–34. The University: Princeton (New Jersey).

[G04] Gibson, N. 2004. Flora and vegetation of the Eastern Goldfields Ranges: part 7. Middle and South Ironcap, Digger Rock and Hatter Hill. Journal of the Royal Society of Western Australia 87 (2): 49–62.

[GK00] Gibson, N., & G. J. Keighery. 2000. Flora and vegetation of the Byenup-Muir reserve system, south-west Western Australia. CALMScience 3 (3): 323–402.

[G60] Gillham, M. E. 1960. Vegetation of Little Brother Island, Cook Strait, in relation to spray-bearing winds, soil salinity, and pH. Transactions of the Royal Society of New Zealand 88 (3): 405–424.

[H90] Harden, G. J. (ed.) 1990. Flora of New South Wales vol. 1. New South Wales University Press.

[H09] Heterick, B. E. 2009. A guide to the ants of south-western Australia. Records of the Western Australian Museum Supplement 76: 1–206.

[H93] Hickman, J. C. (ed.) 1993. The Jepson Manual: Higher Plants of California. University of California Press: Berkeley (California).

[H91] Hubálek, Z. 1991. Biogeographic indication of natural foci of tick-borne infections. In: Dusbábek, F., & V. Bukva (eds) Modern Acarology: Proceedings of the VIII International Congress of Acarology, held in České Budĕjovice, Czechoslovakia, 6–11 August 1990 vol. 1 pp. 255–260. SPB Academic Publishing: The Hague.

[K90] Keighery, G. J. 1990. Vegetation and flora of Shark Bay, Western Australia. In: Berry, P. F., S. D. Bradshaw & B. R. Wilson (eds) Research in Shark Bay: Report of the France-Australe Bicentenary Expedition Committee pp. 61–87. Western Australian Museum.

[K10] Keighery, G. 2010. The naturalised vascular plants of the Pilbara region, Western Australia. Records of the Western Australian Museum Supplement 78 (1): 299–311.

[KM08] Keighery, G. J., & W. Muir. 2008. Vegetation and vascular flora of Faure Island, Shark Bay, Western Australia. Records of the Western Australian Museum Supplement 75: 11–19.

Mummenhoff, K., H. Brüggemann & J. L. Bowman. 2001. Chloroplast DNA phylogeny and biogeography of Lepidium (Brassicaceae). American Journal of Botany 88 (11): 2051–2063.

Mummenhoff, K., P. Linder, N. Friesen, J. L. Bowman, J.-Y. Lee & A. Franzke. 2004. Molecular evidence for bicontinental hybridogenous genomic constitution in Lepidium sensu stricto (Brassicaceae) species from Australia and New Zealand. American Journal of Botany 91 (2): 254–261.

[NL98] Norton, D. A., & P. J. de Lange. 1998. Hebe paludosa (Scrophulariaceae)—a new combination for an endemic wetland Hebe from Westland, South Island, New Zealand. New Zealand Journal of Botany 36: 531–538.

[O88] Ohba, H. 1988. The alpine flora of the Nepal Himalayas: an introductory note. In: Ohba, H., & S. B. Malla (eds) The Himalayan Plants vol. 1. The University Museum, University of Tokyo, Bulletin 31: 19–46.

[PT01] Pemberton, L. M. S., S.-L. Tsai, P. H. Lovell & P. J. Harris. 2001. Epidermal patterning in seedling roots of eudicotyledons. Annals of Botany 87: 649–654.

[SJP60] St. John, H. & W. R. Philipson. 1960. List of the flora of Oeno Atoll, Tuamotu Archipelago, south-central Pacific Ocean. Transactions of the Royal Society of New Zealand 88 (3): 401–403.

[W92] Wilson, E. O. 1992. The Diversity of Life. Harvard University Press: Belknap (USA).

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