Arabidopsis lyrata (L.) O'Kane & Al-Shehbaz

Sand Cress

© SRTurner

Family - Brassicaceae

Habit - Biennial or perennial forb.

	Habit.
© SRTurner

Stem - Ascending to erect, to 30 cm, branched at the base, sparsely pubescent toward the base with simple and 2- or 3-branched, stalked hairs.

	Stem and nodes.
© SRTurner

Leaves - Basal and alternate. Basal leaves 2-4 cm long, spatulate to oblanceolate, subentire or toothed to more commonly pinnately lobed or divided into 3-9 segments, narrowed at the base to a short petiole, usually pubescent on both surfaces with unbranched and 2- or 3-branched, stalked hairs. Stem leaves 1.0-3.0 cm long, narrowed at the base, not clasping, mostly sessile, the lower leaves often pinnately divided, the upper leaves entire to toothed, mostly glabrous.

	Basal leaves.
© SRTurner

	Basal leaf, adaxial.
© SRTurner

	Stem and leaves.
© SRTurner

Inflorescence - Open terminal racemes of a few flowers. Bracts absent.

	Inflorescence.
© SRTurner

Flowers - Sepals 2-4 mm long, oblong-elliptic, green. Petals 4-8 mm long, white, sometimes tinged with light pink or purple. Styles 1.0-1.5 mm long.

	Calyx.
© SRTurner

	Corolla.
© SRTurner

	Corollas.
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Fruit - Siliques, ascending at maturity, straight or slightly arched upward, 1.5-4.5 cm long, flattened parallel to the septum, the valves without nerves. Seeds in 1 row in each locule, 0.9-1.2 mm long, oblong-elliptic in outline, flattened, sometimes narrowly winged at the tip, the surface with a netlike or honeycomb-like pattern of ridges and pits, orangish yellow.

	Fruit.
© SRTurner

Flowering - April - May.

Habitat - Sandstone and dolomite bluffs and adjacent forest areas.

Origin - Native to the U.S.

Lookalikes - None close.

Other info. - In contrast to Missouri's other member of this genus (A. thaliana), Arabidopsis lyrata is both native and conservative, growing only in relatively undisturbed and defined habitats. It is not common in the state, being found in widely scattered areas without a distinct geographical pattern. Its main North American distribution is within the northeastern quadrant of the continental U.S., also extending into Canada. Globally, its distribution is circumboreal.

In appearance the plant is somewhat similar to its sibling A. thaliana, but has much larger flowers. A large population can be fairly showy. Some authors have recognized infraspecific forms, with Missouri's plants being assignable to var. lyrata. The plant was also formerly known as Arabis lyrata.

Arabidopsis lyrata has been eaten by indigenous people of Alaska, who use it as a salad green or cooked vegetable.

Photographs taken near the Paddy Creek Campground, Texas County, MO, 5-13-2019 (SRTurner).