Butte County checkerbloom

Description

Sidalcea robusta is an uncommon species of flowering plant in the mallow family known by the common name Butte County checkerbloom. This rhizomatous perennial herb produces a sturdy stem which can exceed a meter in height. Sidalcea robusta is mostly hairless above with sparse hairs near the base. The leaves are divided into pointed lobes and have bristly hairs on their upper surfaces. The inflorescence is a long, open series of flowers which can be 30–40 cm (12–16 in) in length. The flowers each have five pale pink petals up to 3.5 cm (1.4 in) long that turn yellowish as they dry. Sidalcea robusta is endemic to Butte County, California, where it is known from about 20 occurrences, including some near Chico. It is a resident of chaparral and woodland habitat in mountain foothills. It is an Endangered species listed by the California Native Plant Society Inventory of Rare and Endangered Plants and The Nature Conservancy. Sidalcea is a genus (approx. 25 species) of the botanical family Malvaceae. It contains several species of flowering plants known generally as checkerblooms or checkermallows, or prairie mallows in the United Kingdom. They can be annuals or perennials, some rhizomatous. They are native to West and Central North America. In mid- to late summer the clumps of toothed basal leaves produce erect flowering stems, with 5-petalled mallow-type flowers in terminal racemes, in shades of pink, white and purple. Sidalcea is generally diploid (2n = 20), but polyploidy (4n, 6n) also occurs. Annuality appears to have evolved multiple times (4+) within this genus, although an ancestral annual state with annual paraphyly is also possible. Further, evolution rates within annual Sidalcea lineages appear to be faster than those of perennial lineages, at least when examining nuclear ribosomal DNA (internal and external transcribed spacer regions).