Vascular Plants of Wisconsin

Draba verna L.
spring whitlow-grass
Family: Brassicaceae

native: no
type: annual forb

plant flowers and fruit basal rosette
 

Draba verna is a small annual plant usually found on sunny sites of low productivity. Most plants flower very early in the growing season to take advantage of the spring moisture on sites that will become very dry later in the summer (the Latin epithet "verna" refers to Spring). A smaller number of plants can be found later in the season, depending on soil moisture.

They are commonly overlooked, even when in full flower, because of their very small size. The plants are reported to reach heights up to about 30 cm (1 foot), but most of the plants that I have seen in Wisconsin have been less than 8 cm tall, with some flowering at a height of only 2 or 3 cm. All the leaves are at the base of the plant, arranged radially in a pattern commonly known as a "basal rosette". There are no leaves on the flowering stem. The four white flower petals are deeply lobed at the tip and may give the impression of eight petals if hastily judged. Petals are about 1.5-2.5 mm long.

Draba verna is undoubtedly more common in Wisconsin than is indicated by the distribution map. Because it is so small and it flowers so early it is probably frequently overlooked. There are recent records from Brown, Door and Marinette Counties that have not yet been added to the list of vouchers upon which the distribution maps are based. Based on 5 years of phenology data from Brown County the average date of first flower is 4/16, with the earliest date 4/01.

 

 

 


known distribution based on vouchers

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