Whitetop

taxobox
name = Whitetop

---

regnum = Plantae
unranked_divisio = Angiosperms
unranked_classis = Eudicots
unranked_ordo = Rosids
ordo = Brassicales
familia = Brassicaceae
genus = "Lepidium"
species = "L. draba"
binomial = "Lepidium draba"
binomial_authority = L.
subdivision_ranks = subspecies
subdivision = "Lepidium draba draba"
formerly "Cardaria draba"
"Lepidium draba chalepensis"
formerly "Cardaria chalepensis "|

Whitetop or hoary cress ("Lepidium draba" L. formerly "Cardaria draba") is native to western Asia and eastern Europe and is an invasive species in North America, introduced by contanimated seeds in the early 1900s.

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, are oblong or tapering the point, with broad bases that clasp the stalk. Whitetop has sligtly 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 sepals.

Distribution in United States

References

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

External links

* [http://www.invasivespeciesinfo.gov/plants/whitetop.shtml Whitetop] USDA National Invasive Species Information Center.