Common Peppercress

Lepidium africanum (Burm.f.) DC.

Synonyms - Lepidium ruderale

Family: Brassicaceae

Names:

Peppercress
Rubble Peppercress.

Other names:

Common Pepper-cress
Pepperweed
Poor Man's Lucerne
Rubble Peppercress

Summary:

An erect herb, usually about 300 mm tall with a basal rosette of stalked, toothed leaves and a single stem with stalked leaves, branched at the top to carry many 2 seeded pods held at right angles to the stem.

Description:

Cotyledons:

Two. Club shaped. Tip rounded. Sides convex. Base tapered. Surface hairless. Petiole shorter than the blade and merging with it.

First leaves:

Oval, Tip pointed. Edges toothed. Long scattered hairs.

Leaves:

Stipules -
Petiole - On all leaves.
Blade - Elliptical, edges serrated, lower leaves up to 100 mm long x 3-10 mm wide. Hairless or sparse tiny hairs.
Stem leaves - Spear shaped. Grading in length to the uppermost leaves being less than 10 mm long. Upper leaves may have smooth edges or be sharply toothed near the tip.

Stems:

Erect, rigid, wiry, branched, up to 700 mm tall, often woody at the base. Hairless.

Flower head:

Long, slender raceme, 50-150 mm long, on the end of branches and often forming a broad panicle. It often has crowded flowers at the top, pods in the middle and papery partitions (left after seed is shed) at the bottom all at the same time on the same stem.

Flowers:

Small and white.
Ovary - Sessile stigma.
Sepals - 0.75 mm long.
Petals - 4, white and less than 0.5 mm long or absent.
Stamens - 2 or 4
Anthers -

Fruit:

Oval, 1-3 mm long x 1.5 mm wide, 2 seeded, flattened, pendulous capsule with a small notch at the top, wingless. On stalks 1-3 mm long held at right angles to the stem. Seeds attached to the top of the capsule. Opens and releases seed when ripe.

Seeds:

Orange brown, dull. Narrowly egg shaped, small, 1.5 mm long x 0.75 mm wide, flattish and grooved on one side. Tip rounded, Edges smooth. Base indented or stalked.

Roots:

Taproot.

Key Characters:

Toothed, undivided, lance shaped, petiolate leaves. Pod wingless, 2-3 mm long, with small notch at the top. 2 stamens. Long and loose raceme when in fruit. Branches without spines. Stem leaves petiolate.
Hairless wiry stems.
Small white flowers.
Pods with 2 seeds.

Biology:

Life cycle:

Annual or biennial. Germinates from autumn to spring and flowers a few months later. Usually it completes its life cycle before the onset of summer drought but may over summer in moist areas and re shoot to set another lot of seed when conditions improve. Forms from drier areas may go dormant over summer.

Physiology:

Reproduction:

By seed.

Flowering times:

Most of the year in western NSW.
Most of the year in SA.

Seed Biology and Germination:

Vegetative Propagules:

Occasionally dormant rootstock.

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Most abundant in overgrazed situations.

Origin and History:

Africa.

Distribution:

ACT, NSW, QLD, SA, VIC.

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Temperate. Mediterranean.

Soil:

On most soil types.

Plant Associations:

In most communities.

Significance:

Beneficial:

Relatively palatable and provides feed often when little else is available and is sometimes referred to as "poor man's lucerne".
Used raw or cooked as a cress for human consumption.

Detrimental:

Weed of crops, pastures, lucerne, newly sown irrigated pastures and wasteland.

Toxicity:

May taint dairy products and eggs.
May adversely affect working horses.

Legislation:

None.

Management and Control:

Establish competitive pastures.
Apply herbicides in crop.

Thresholds:

Eradication strategies:

Manually remove isolated plants.
Prevent seed set. Spray small infested areas with 10 g/ha Eclipse® plus 500mL/ha of Brodal® plus 1% spray oil in winter each year.
Most of the Brassicaceae weeds have dormant seeds that continue to germinate throughout the season and for several years. They often mature and set seed very quickly. Manual removal is effective but must be done at least every 8-10 weeks. Once pods are formed, seed will often mature even if the plant has been uprooted. Soil disturbance often leads to a flush of seedlings.
Many are somewhat unpalatable, so grazing only offers partial control. They often flourish in under-grazed, sunny areas.
In bushland situations, fairly selective control can be achieved with 100 mL spray oil plus 0.1 g Eclipse® or 0.5 g Logran® in 10 L water. 5 mL Brodal® is often added to this mix to provide residual control of seedlings. Spray the plants until just wet from the seedling stage up to pod formation.
Isolated plants should be removed manually and burnt if flowering or seeding and a 10 m buffer area sprayed with 10 mL Brodal® in 10 L water.
500 mL/ha of glyphosate(450g/L) can be used at flowering to reduce the seed set of most species on roadsides without causing significant damage to most native plants.
Wick application with 1 part glyphosate(450g/L) in 2 parts water or overall spraying with 100 mL glyphosate(450g/L) in 10 L water provides reasonable control of most Brassicaceae species though Wild Radish tends to regrow.

Herbicide resistance:

Biological Control:

Related plants:

Flax-leaf Alyssum (Alyssum linifolium)
Wall Cress (Arabidopsis thaliana)

Black Mustard (Brassica nigra)
Broccoli (Brassica oleracea var. italica)
Brussels Sprouts (Brassica oleracea var. gemmifera)
Cabbage (Brassica oleracea var. capitata)
Cauliflower (Brassica oleracea var. botrytis)
Chinese Cabbage (Brassica chinensis)
Indian Mustard (Brassica juncea)
Kale (Brassica oleracea var. acephala)
Kohlrabi (Brassica oleracea var. gongylodes)
Mediterranean Turnip (Brassica tournefortii)
Rape or Canola (Brassica napus var. napus)
Rapeseed (Brassica rapa var. sylvestris)
Savoy cabbage (Brassica oleracea var. sabauda)
Smooth Stemmed Turnip (Brassica barrelieri subsp. oxyrrhina was Brassica oxyrrhina)
Swede (Brassica napus var. napobrassica)
Turnip (Brassica rapa var. rapa)
Twiggy Turnip (Brassica fruticulosa)
Winter Rape (Brassica napus var. biennis)
Brassica elongata

Sea Rocket (Cakile maritima)
White Ball Mustard (Calepina irregularis)
Shepherd's Purse (Capsella bursa-pastoris)
Common Bittercress (Cardamine hirsuta)
Wood Bittercress (Cardamine flexuosa) is not in WA.
Ward's Weed (Carrichtera annua)
Wall Rocket (Diplotaxis muralis)
Sand Rocket (Diplotaxis tenuifolia)
Heliophila pusilla
Oval Purse (Hornungia procumbens was Hymenobolus procumbens)

Argentine Peppercress (Lepidium bonariense) is often found around granite rocks.
Common Peppercress (Lepidium africanum) is common in WA.
Field Cress (Lepidium campestre) has clasping stem leaves.
Garden Cress (Lepidium sativa)
Hoary Cress (Lepidium draba was Cardaria draba)
Lesser Swinecress (Lepidium didymum was Coronopus didymus)
Matted Peppercress (Lepidium pubescens)
Perennial Peppercress (Lepidium latifolium)
Virginian Peppercress (Lepidium virginicum)
(Lepidium oxytrichum)
(Lepidium perfoliatum)

Sweet Alyssum (Lobularia maritima)
Common Stock (Matthiola incana)
Night-scented Stock (Matthiola longipetala)
Muskweed (Myagrum perfoliatum) is not in WA.
Ball mustard (Neslia paniculata)

Cultivated Radish (Raphanus sativus).
Sea Radish (Raphanus maritimus).

Turnip Weed (Rapistrum rugosum)
Watercress (Rorippa nasturtium-aquaticum)
White Mustard (Sinapis alba) has white seed.
Charlock (Sinapis arvensis)

Sisymbrium altissimum is not in WA.
Smooth Mustard (Sisymbrium erysimoides)
London Rocket (Sisymbrium irio)
Hedge Mustard (Sisymbrium officinale)
Indian Hedge Mustard (Sisymbrium orientale)0
Sisymbrium runcinatum
African Turnip Weed (Sisymbrium thellungii) is not in WA.

Succowia balearica is in Kings Park in Perth.

Plants of similar appearance:

Hoary Cress (Lepidium draba was Cardaria draba) is similar but the inflorescence tends to be umbrella shaped and broad and spreading. The fruits and distinctive.
Field Cress (Lepidium campestre) has clasping stem leaves and is taller.
There are 27 native species of Lepidium.
The native Brassicaceae species usually have short, broad and smooth pods.

References:

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P382.

Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P186. Diagram.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P326. Photo.

Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).

Moerkerk, M.R. and Barnett, A.G. (1998). More Crop Weeds. R.G. and F.J. Richardson, Melbourne. P69. Diagrams. Photos.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.