''Lepidium draba'', the whitetop or hoary cress,
or Thanet cress, is a
rhizomatous
In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...
perennial
A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...
flowering plant
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
in the family
Brassicaceae
Brassicaceae () or (the older) Cruciferae () is a medium-sized and economically important family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous plants, while some are shrubs. The le ...
. It is native to western Asia and southeastern Europe and widely introduced elsewhere.
Description
Whitetop is a perennial herb that reproduces by seeds and by horizontal creeping roots. The stem is stoutish, erect or spreading, 10 to 80 cm tall, branched, covered sparsely with ash-colored soft hairs to heavily covered. The leaves are alternating, simple, and mostly toothed. The basal leaves are 4 to 10 cm, have a slight stem (petiole), and are long and flat, lance-shaped to egg-shaped, with the narrow end attached to the stalk. On the upper part of the stem the leaves are attached directly to the stalk (sessile), are 2 to 6.5 cm long, and are oblong or tapering the point, with broad bases that clasp the stalk. Whitetop has slightly domed flower clusters in which the individual flower stalks grow upward from various points off the branch to approximately the same height (corymb-like). The petals are white, clawed, and 3 to 5 mm long, about twice the length of the
sepal
A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coined b ...
s.
Distribution
It is native to western Asia and southeastern Europe and is an invasive species in North America, introduced by contaminated seeds in the early 1900s. Also known as ''Cardaria draba'', hoary cress is a weed in much of south-east and south-west Australia as well.
Distribution in United States
References
External links
Species Profile - Whitetop (''Lepidium draba'') National Invasive Species Information Center,
United States National Agricultural Library
The United States National Agricultural Library (NAL) is one of the world's largest agricultural research libraries, and serves as a national library of the United States and as the library of the United States Department of Agriculture. Located ...
. Lists general information and resources for Whitetop.
Hoary cress - Lepidium draba Invasive Plant Atlas of the United States,
Cardaria_spp Bugwood Wiki - Invasive Pest Management
Other reading
Agriculture Research Service (1970) "''Cardaria draba'' (L.) Deav." ''Selected Weeds of the United States'' Agriculture Research Service United States Department of Agriculture, Washington, DC, p. 200
{{Taxonbar, from=Q149440
draba
''Draba'' is a large genus of flowering plants in the family Brassicaceae, commonly known as whitlow-grasses (though they are not related to the true grasses).
Species
There are over 400 species:
*'' Draba abajoensis'' Windham & Al-Shehbaz
*'' ...
Plants described in 1753
Taxa named by Carl Linnaeus