Scientific Name: Erysimum teretifolium
Also known as the Ben Lomond Wallflower, this is a short-lived perennial plant, or occasionally an annual, of the mustard family. Seedlings form a basal rosette of leaves which then wither as the main stem develops a terminal spike. The flowers are a deep yellow with petals 1.3-2.5 centimeters (0.5-1.0 inch) long. The fruit, a slender capsule, reaches 10 centimeters (4.0 inches) in length and is covered with three-parted hairs. Characteristics that separate this plant from other wallflowers include simple, narrowly linear leaves that have small marginal teeth and a purplish cast.
This species of wallflower is endemic to pockets of sandstone soils in the Santa Cruz Mountains. It is found in open areas within northern maritime chaparral and within the scattered ponderosa pines in the sand parklands. The largest populations are found on ridgelines where underlying fossilized sand dollar beds inhibit the growth of all but herbaceous perennials and annuals.
Threats to the species include the direct removal of habitat by sand quarrying and residential development. Alteration of habitat may also be occurring in the form of increased canopy density within the Ben Lomond sandhills as a result of fire suppression.