When we think of the mustard family (Brassicaceae or Cruciferae), images of fields of yellow or violet-flowered weeds usually come to mind. Fallow agricultural fields dominated by wild mustard (Brassica spp., Hirschfeldia incana) or wild radish (Raphanus sativus) make European visitors feel right at home. These widespread weeds have found their way onto vacant lots and dryland farms in every county of the state. Many other nonnative members of the family are familiar to us, including the alarmingly invasive perennial pepperweed (Lepidium latifolium) and hoary cress (Cardaria draba). The Jepson Manual lists 59 non-native cruciferous taxa present in California.

But there’s a kinder, gentler side to the family. This side is represented by 264 native taxa in 44 genera and it includes some of our most endangered species. Some of the more elegant examples include the jewelflowers (Streptanthus spp. and Caulanthus spp.), rock cress (Arabis spp.), and Draba spp. Representatives are found from the seashore to 8,200-foot alpine elevations and into the deserts. Ninety-nine taxa in the Brassicaceae are considered to have special status (i.e., they are listed by the state, the federal government, or CNPS), of which 17 are listed as Endangered.

One very attractive group is the wallflowers (Erysimum spp.), which include annual herbs to short-lived perennials. Wallflowers produce basal rosettes of leaves with leafy stems. They are mostly found among dunes and coastal scrub throughout coastal California, although one species occurs above 6,000 feet. In California, the genus Erysimum includes 13 native and three nonnative taxa. Five are listed as state or federally Endangered and another five are listed by CNPS.

A relatively frequently encountered species is the San Francisco wallflower (Erysimum franciscanum). This biennial or short-lived perennial produces one to several stems up to two feet tall. Its leaves are coarsely toothed, linear to oblanceolate, and have branched hairs. Basal leaves are one to eight inches long. Cream to yellow flowers in the family’s typical cross-shaped (crucifer) four-petaled form are produced from March through June. Fruits consist of elongated siliques up to five inches long.

San Francisco wallflower grows in open, woody, or brushy places in rocky to sandy soil, decomposed granite, or serpentinite. The species occurs near the coast from Santa Cruz County northward to Sonoma County. Within San Francisco, Erysimum franciscanum has been recorded historically from Point Lobos, Lone Mountain, Laguna Honda, and Lake Merced. It can still be found at Grandview Park, Hawk Hill, 14th Avenue and Ortega, above Baker Beach, and on the serpentine bluffs below Battery Boutelle on the Presidio.

San Francisco wallflower has no formal state or federal status as a protected species. It is on the CNPS List 4, which is considered a watch list. Species on this list are of limited distribution or infrequent throughout a broader area in California and their vulnerability or susceptibility to threat appears low at this time. While these species cannot be considered “rare” from a statewide perspective, they are uncommon enough that their status should be monitored regularly. Few of the plants on List 4 meet the definitions of rare plants pursuant to the California Fish and Game Code (Section 1901, Chapter 10 of the Native Plant Protection Act or Sections 2062 and 2067 of the California Endangered Species Act).

Even though San Francisco wallflower doesn’t qualify as rare in the state, it is sufficiently uncommon in the city to warrant protection. It is indeed a gem when discovered on the loose sandy slopes of Grandview Park or elsewhere. Watch for it beginning in March. Don’t be a wallflower; get out and look for the wallflowers!