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Spiny Peppercress!

A miserable little endangered plant

by Valda Dedman

When the Club visited Beeac swamp during an excursion in mid 1996, members were shown a small plant by D.N.R.E. officer, Phil du Guesclin, but did not become wildly enthusiastic about it, in spite of its rarity. Spiny Peppercress, Lepidium aschersonii could be regarded as a miserable little plant, scrawny, spiny, 30 cm tall at most, with insignificant little flowers.

I became interested in this plant when I recently had to prepare comments on the Lake Beeac Catchment Management Plan.

peppercress1Lepidium is a cosmopolitan genus of 150 species, of which 35 are indigenous to Australia. Victoria has 12 endemic species and 8 introduced. Many of the native lepidiums are rare or restricted in distribution, and some have become extinct. Lepidium aschersonii is classed as endangered in Victoria and is thought to be close to extinction in New South V\/ales, where it occurs in the NE western plains and on marginal central western slopes. There is an isolated occurrence, which may be an introduction, at Corackerup Wildlife Reserve in Western Australia.

In Victoria Spiny Peppercress occurs on 12 sites between Mortlake and Beeac, with an outlying population at Lake Omeo. Only one of these sites is in a biological reserve (Lake Beeac). It was collected in 1875 from Lake Corangamite and in 1883 from Williamstown. I wonder if it ever occurred in the Geelong district. I would be pleased to hear of any local reports. Has it been merely overlooked? Much of its habitat has been destroyed by drainage, cultivation, or heavy grazing.

Two other lepidium species on the western volcanic plains and I would appreciate local records of them also. L. pseudotasmanicum is common and widespread, usually in rocky situations, while L. hyssopifolium has been rarely reported from western Victoria and is currently known from only two localities to the north and north-east of Melbourne.

L. aschersonii generally grows on seasonally flooded wetlands with heavy cracking black clays, but is sometimes found on adjacent drier sites. At Lake Beeac it grows on the steep banks of the eastern shore of the salt lake and extends to the waters edge in a saltmarsh dominated by Austral Seablite, Suaeda australis. Other saltmarsh species there include Streaked Arrowgrass, Triglochin striata, Blown Grass, Agrostis avenacea, Australian Salt Grass, Distichlis distichophylla and Marsh Club-rush Bolboschoenus medianus. It also occurs in the south-western and northern fringes of Beeac swamp, and on adjacent private property.

The name "lepidium" comes from the Greek word for "scale" and refers to the shape of the squat flattened fruits, which split open to eject seeds. "Aschersonii" honours the professor of botany at the Botanic Museum at the University of Berlin.Lepidium aschersonii is a perennial herb, arising annually from underground rootstock. It is distinguished by the spines on its tangled branchlets and at the tip of the flowering raceme. Both stems and leaves are hairy. The leaves at the base of the plant are up to 12cm long and pinnately lobed, but become smaller, narrower and stalkless with increasing height up the stem. The greenish-Mite flowers are barely visible and occur in November to December, to be followed by oval stalked fruits only a few millimetres long. The fruits are smooth and notched at the tip and contain two seeds, each in its own separate chamber.

peppercress2Cresses belong the mustard family Brassicacae, which includes many of our vegetables, such as cabbage, cauliflower, radish and turnip. They contain mustard oils, manufactured by the plants as a defence (although obviously not totally effective) against herbivores. Heat inactivates the oils and makes the taste pleasantly bland. Aborigines in South Australia steamed bundles of lepidium leaves in earthen pits. Spicy seeds can be ground as pepper. The European garden cress is Lepidium sativum, a salad plant which is cut young and used with mustard. It contains large amounts of vitamin C.

Garden cress germinates easily, but the National Botanic Gardens in Canberra experienced difficulties establishing plants from seed of Spiny Peppercress collected by Neville Scariett in 1982 from Beeac and Omeo. Attempts have been made to introduce the species to Lake Goldsmith State Game Reserve near Skipton, but although planted seedlings have survived, there has been no natural regeneration there.

At Beeac the opportunity presents itself to put in place measures which could aid the preservation of this endangered species. One stand, that was fenced off after severe damage by sheep grazing in 1982-83, has regenerated and plants also appeared in the 1986-87 season from soil-stored seed in an adjacent area. I do not know the effect of the past two dry seasons, or the extent of the species on private land

In our submission on the Lake Beeac Catchment Management Plan we recommended an active program to protect Spiny Peppercress. This would include a thorough survey to ascertain present local distribution, involving local landowners in identification and propagation, and the production of a brochure on the species. We believe the plant could become a key feature of a wetland education program, which would also assist in the management of the entire catchment.

REFERENCES:
Briggs, J.D., Leigh, J.H. (1995). Rare or threatened Australian plants. Rev. ed. CSIRO, Canberra.
Flora of Australia (1 981 -). Bureau of Flora & Fauna, Canberra.
Foreman, D.B. and Walsh, N.G., eds. (1993-1997). Flora of Victoria. Inkata Press, Melbourne.
Low, T. (1988). Wild food plants of Australia. Angus & Robertson, North Ryde, N.S.W.
Romanowski, N. (1997). Beeac swamp reserve: report to the Victorian Wetland Trust. Dragonfly Aquatics, Colac.
Sinclair Knight Merz (1997). Lake Beeac Catchment Draft Management Plan. Draft. D.N.R.E., Melbourne.
Society for Growing Australian Plants Maroondah (1991). Flora of Melbourne. Hyland House, Melbourne.
Photographs: John Eichler