[The Genus Alyssum East of the Cascade Mountains of Oregon and Washington]

Pale Alyssum, Pale Madwort, Small Alison, Small Alyssum

Alyssum alyssoides

Synonym: Alyssum calycinum

Pale Alyssum, Pale Madwort, Small Alison, Small Alyssum: Alyssum alyssoides (Synonym: Alyssum calycinum, Clypeola alyssoides)

The photo above shows a close-up of the inflorescence of pale alyssum as seen on BLM lands at Cowiche Canyon, several miles west of Yakima, WA.............March 28, 2007.

Pale Alyssum, Pale Madwort, Small Alison, Small Alyssum: Alyssum alyssoides (Synonym: Alyssum calycinum, Clypeola alyssoides)The photo at right is a close-up of the inflorescence of pale alyssum as seen seen along Road 22 north of the boundary of the Ochoco N.F........May 24, 1998.

Characteristics:

Also known as small alyssum, pale alyssum is a small, weedy annual or biennial with simple to branched stems from 6-30 cm high. The herbage of the stems and inflorescence consists of whitish to grayish appressed , star-like hairs. The narrowly oblanceolate to spatulate leaves range from 5-25 mm long and have entire margins. The lower stem leaves may have short petioles while those of the upper stems are sessile.

The inflorescence is a tightly packed inflorescence which elongates in fruit. The spreading pedicels are about as long as the silicles. The sepals are up to 2 mm long and are covered with star-like hairs. They are persistent and become reflexed when in bloom. The 4 petals are white, cream or light yellow and 3-4 mm long with a small notch at the tip (See the photo at right.). The fruits are silicles which are ovate-oval in shape, with flattened margins but bulged in the middle. The silicles measure 3-4 mm long.

Habitat:

Pale alyssum may be found in dry, disturbed soils along roadsides, road cuts, fields, quarries and other disturbed places, especially to the east of the Cascades.

Range:

A native of Europe, pale alyssum may be widely found across much of the United States.

Pale Alyssum, Pale Madwort, Small Alison, Small Alyssum: Alyssum alyssoides (Synonym: Alyssum calycinum)

Developing fruits of pale alyssum as observed on scablands along the Stein's Pillar Trail #837, Ochoco National Forest.......June 2, 2018. This species of alyssum is the only one found in the Pacific Northwest to have sepals that persist until the fruits mature, which helps ID this photo to species.

Pale Alyssum, Pale Madwort, Small Alison, Small Alyssum: Alyssum alyssoides (Synonym: Alyssum calycinum, Clypeola alyssoides) - Pale Alyssum, Pale Madwort, Small Alison, Small Alyssum: Alyssum alyssoides (Synonym: Alyssum calycinum, Clypeola alyssoides)

The photo at left shows a close-up of the inflorescence and upper stem of pale alyssum. The photo at right shows a whole plant. Both plants seen on BLM lands at Cowiche Canyon, several miles west of Yakima, WA.............March 28, 2007.
Paul Slichter