Alyssum desertorum Stapf

Desert Madwort

© SRTurner

Family - Brassicaceae

Habit - Annual forb with stellate, 8-20 rayed, mostly appressed, nonglandular hairs.

Stem - To 5-18 cm long, ascending to erect, with appressed stellate hairs.

	Stem and leaves.
© SRTurner

Leaves - Alternate, simple, sessile or nearly so, linear to narrowly oblanceolate, 0.5-2.5 cm long, densely pubescent with stellate hairs.

	Leaves.
© SRTurner

Inflorescences - Racemes, lacking bracts.

	Inflorescence.
© SRTurner

	Inflorescence.
© SRTurner

Flowers - Sepals ascending to erect, 1.5-2.0 mm long, oblong-elliptic, deciduous soon after flower opens. Petals 2-3 mm long, shallowly notched at the tip, yellow. Styles 0.3-0.7 mm long.

	Sepals.
© SRTurner

	Corollas.
© SRTurner

Fruits - Silicles, circular, 2.5-4.5 mm long, inflated at the center, broadly flattened at margin, glabrous and glaucous at maturity. Seeds ovate, 2 per locule, 1.2-1.5 mm long, slightly margined or not margined.

	Fruits.
© SRTurner

Flowering - April - June

Habitat - Open disturbed areas.

Origin - Native to Europe.

Lookalikes - Alyssum alyssoides. Both species are rare in Missouri.

Other info. - This small plant has been found thus far in only one location in Missouri. It is far more common in western regions of the continental U.S. Missouri lies far east of its normal range and is not expected to prove suitable habitat for large populations. The plant is recognized by its small stature, dense covering of conspicuous stellate hairs, and tiny four-petaled flowers. A closely related species, A. alyssoides, appears similar except that the sepals on developing fruits are retained longer.

Photographs taken at Hot Springs State Park, WY, 5-10-2025, and near Graycliff, Sweet Grass County, MT, 5-10-2025 (SRTurner).