Slatsz' plant photo-biography: Draba verna, whitlow grass; Brassicaceae

Draba verna, whitlow grass; Brassicaceae

From “A Sand Country Almanac”, Aldo Leopold, 1949

“Its perfume, if there is any, is lost in the gusty winds. Its color is plain white. Its leaves wear a sensible wooly coat. Nothing eats it; it is too small. No poets sing of it. Some botanist once gave it a Latin name, and then forgot it. Altogether it is of no importance—just a small creature that does a small job quickly and well."

Draba verna was once thought to have been introduced to the United States but now it is seen to be native in the United states, to much of Eurasia and some of North Africa. Distribution maps do not show it in the American Midwest. [Most sites I access still consider it introduced. Only a couple of sites consider it native but I like the plant … so.]

Paul Slichter says it is: “… one of the most abundant flowering plants underfoot in the west.”

Draba verna, is the third plant I saw in bloom in 2012. It is a member of the mustard family, Brassicaceae. It has the four petal blossom characteristic of the mustard family.

Montana Plant life says leaves are edible, raw, in small quantities. At ½ to 1 inch long and about 1/8^th inch wide satisfying one’s appetite seems unlikely.

They say the common name for Draba verna, ‘spring whitlow grass’, comes from its use as a treatment for ‘whitlows’, a herpes of the fingers.

And they say it has ‘agents’ that can produce contraction in living tissue and promote the healing of wounds.

Draba verna is tiny and easy to overlook except that it sometimes shows up in dense patches. The blossoms are only about a quarter of an inch across.

Draba verna may be only an inch tall. It can be eight inches tall. There are no [cauline] leaves on its slender flower-stalk [scape]. The flower-stalk can appear to be simple but it will branch when it matures. Each branch will have a blossom at the apex.

Draba verna is a winter annual. It goes to seed in April but its seeds have a mechanism that prevent germination till three months pass, the temperature is reduced, there is moisture and they are exposed to light according to Kentucky researchers.

The seeds germinate in the fall.

Buds are said to be produced in winter. I’ll look for them this winter. [I didn’t find any till March in 2013. Failed to look for them in 2014.]

A two layer ‘rosette’ of red leaves develops, the lower layer is ‘petiolate’, it has leaf stalks, ‘petioles’. The top layer has no leaf stalks. It is ‘sessile’. [2013. The early leaves mostly green, though reddish. Red leaves later.]

The basal leaves of Draba verna are green later in the year when the weather warms.

The leaves are ½ to 1 inch long.

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The margins of the leaves are smooth [entire] or they can have small teeth. I have not noticed teeth on the leaves. Something to look for next year.

Hairs

The leaves have ‘trichomes’. Trichomes can be several different structures that develop on the ‘epidermal cells’, surface cells, of a plant. In this case they are hair like and the hairs tend to be forked. They can be three-forked. [2013 photo [323? of smooth leaves and leaves with trichomes.]

Both surfaces of the leaves are ‘hairy’. The ‘hairs’ on the leaves are thought to help protect the leaves from frost. The forked hairs sometimes extend a short distance up the stem.

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The red color of the leaves is thought to protect the leaves from bright winter sunlight.

Red leaves are said to be expensive for a plant to maintain and they are said to be less efficient in photosynthesis than green leaves. But reduced efficiency is a good thing in cold bright light [or bright light during summer drought] because the transportation system of the plant is restricted. The leaves need to produce less food for the plant. If food builds up in the leaves it causes damage. The extra ‘cost’ of maintaining the red color is worth it.

Draba verna inflorescence is a ‘loose raceme’.

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The blossoms have 6 stamen. [A small violation of the rule of 4 or 5 flower parts for dicots.]

The Ovary is superior, it is above the attachment of petals and sepals. The pistil has no style. The stigma is ‘capitate’, head shaped.

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Draba verna has four sepals covering its buds and opening behind its four petals. They open away from the petals. The sepals have the forked ‘hair’ of the leaves and lower stem, presumably helping to protect the winter bud from frost.

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Draba verna’s pistil quickly develops into a fruit called ‘a silicle’ from 1/8^th inch to ½ inch long containing 30 to 60 seeds. The seeds are about 1/32^nd inch.

The silique and the silicle are fruits of the mustard family. They are similar except the silicle is much shorter than the silique. It is less than twice as long as broad.

The seeds of both are attached to a septum, an interior wall dividing the cavity of the silique or silicle.

The fruit of Draba verna is a silicle. It is broad and short.

Siliques and silicles are ‘dehiscent’, they open when they are ripe. It is thought that they open because the outside dries more quickly than the inside. The fruit breaks open and the two sides of the fruit fall away from each other. I hope to get photos of open husks, next spring.

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There are said to be two varieties, Draba verna var. verna and Draba verna var. boerhaavii. Variety boerhaavii has fruit twice as long as broad, siliques, not silicles.

Paul Slichter says Var. boerhaavii’s fruit is 4-5 mm long and 3.5 mm wide. Not a lot of discrepancy between the two descriptions but a little.

It seems both varieties are present in Drumheller Springs Park. This photo is from April 11, 2012, late in the year for Draba verna. The fruit look to be twice as long as they are broad.

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