Pepperworts & Swine-cresses
What are they?
These members of the brassica family are all in the genus Lepidium. They vary quite a lot in their outward appearance, with some being creeping, mat-forming plants, while others may grow to over a metre tall. The common link is found in their flowers, which tend to be individually very small, but generally carried in massed clusters. The flowers are often rather uneven with petals of varying size, or even missing altogether. Most have a peppery bite if tasted, while some have something of an unpleasant smell.
Where are they found?
Most species are found as 'weedy' plants in disturbed ground in farmland, gardens or waste places. Some are found on grassy verges while Dittander is also found at the edges of saltmarsh.
Identification
Overall growth style is useful for narrowing the search - upright or mat-forming, tall or short, for example. Leaf shape should be checked, as well as details of any seed capsules.
Lesser Swine-cress Lepidium didymum
Introduced from South America and still spreading across the region in all kinds of disturbed soils, especially in gardens and arable farmland where soil is trodden or compacted. Flowers July to September. A low, mat-forming species with small, finely-cut, compound leaves and tight clusters of almost petalless flowers. Seed capsules are rounded and carried in pairs. Young plants start as small, leafy rosettes and look very different to the tangled mats of older plants.
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Common Swine-cress Lepidium coronopus
A common and widespread species of disturbed ground throughout the region, though less common on sandy soils. Particularly common on pathways, gateways and other places where the soil gets compacted. Flowers June to September. A low, rosette-forming species with coarsely-cut, compound leaves and tight clusters of tiny flowers. Seed capsules are rounded and carried in pairs. Flowers with more obvious white petals than those of Lesser Swine-cress and leaves larger and more coarsely lobed.
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Hoary Cress Lepidium draba
Introduced from southern Europe in the 19th Century and still increasing. Most common along grassy roadsides in coastal and low-lying areas and along the drier edges of saltmarshes, but increasingly spreading inland, especially along railways. Flowers May to June. A low but strong-growing, perennial species that forms extensive colonies. The tiny, four-petalled flowers are carried in flat heads that from a distance could be mistaken for Wild Carrot. Seed capsules are inverted heart-shaped.
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Field Pepperwort Lepidium campestre
Introduced from southern Europe. An annual of field edges and disturbed places, found scattered throughout our area and generally scarce, though locally frequent in parts of north-east Suffolk. Flowers May to August. An upright species with flowers carried in upright spikes which often branch at the base. Leaves clasp the stem and are held rather stiffly outward. Seed capsules are like spoons or small shovels - compare the shape of the tip, with its shorter, pointed style, with that of the very similar Smith's Pepperwort.
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Smith's Pepperwort Lepidium heterophyllum
A native biennial or short-lived perennial of grassy and heathy places, found scattered throughout our area and generally scarce. Flowers May to August. An upright species with flowers carried in upright spikes which often branch at the base. Leaves clasp the stem and are held rather stiffly outward. Seed capsules are like spoons or small shovels - compare the shape of the tip, with its longer, pointed style, with that of the very similar Common Pepperwort.
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Narrow-leaved Pepperwort Lepidium ruderale
Once considered native to our saltmarshes edges, but now generally considered to be an ancient introduction and more likely to be found along the edges of salted highways, especially the A47 in Norfolk and the A14 in Suffolk. Flowers May to July, with small, often uneven or misshapen, cream-coloured petals. Often a very small species with fine leaves and thus easily missed, but may grow to around 30cm in height and become bushy with branched flower spikes. Seed capsules disc-shaped.
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Cultivated Cress Lepidium sativum
Introduced but a species long in cultivation and of uncertain origin. Occasionally found where self-seeding from birdseed and once grown commercially as a component of 'mustard and cress', but now superceded in that role by Oil-seed Rape seedlings. Flowers May to November. A very variable plant but typically with deeply lobed leaves, the lobes broader on lower leaves, narrower on upper leaves.
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Virginia Pepperwort Lepidium virginicum
(Least Pepperwort) Native to North America with less than ten records from our region. Possibly occurs as a grain seed alien, with records from disturbed and industrial areas. Flowers June to August. A small, upright species with compound basal leaves that usually turn red and wither by flowering time. Stem leaves linear with uneven teeth along the margin. Flowers small but relatively showy for a pepperwort, with well-developed petals. Seed capsules disc-shaped.
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Dittander Lepidium latifolium
A native species of the drier, upper parts of saltmarshes but only common in the south-east corner of our region, where it is found around coastal estuaries. Also established in one or two places across the region in other estuarine sites, as well as a plant of salty road edges and may continue to increase in such places. Flowers June to July. Flowers are tiny but carried in large, frothy masses. Petals often purplish on the back. A tall and striking species, often growing to a metre or more high. Leaves broad, greyish green and waxy.
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