Coast Microseris (Microseris bigelovii) COSEWIC assessment and status report: chapter 3

Species Information

Name and classification

Scientific Name:
Microseris bigelovii (A. Gray) Schultz-Bip.
Synonym:
none
Common names:
coast microseris, coastal silverpuffs, microséris de Bigelow
Family:
Asteraceae (aster family)
Major plant group:
Eudicot flowering plant

Microseris bigelovii is a clearly defined taxon that presents no classification problems.

Description

Microseris bigelovii is a taprooted annual with erect to ascending leafless flower stalks (scapes) 4-35 centimetres (cm) tall (Figure 1). The leaves are all basal, 3-25 cm long, and linear to narrowly spoon-shaped (oblanceolate), entire or coarsely pinnately cut with slender or broad tapering lobes or teeth. The leaves exude a milky juice when broken.

Figure 1. Illustration of Microseris bigelovii (artwork by Elizabeth J. Stephens, Douglas et al. 1998, with permission).

Illustration of Microseris bigelovii

The solitary, terminal heads are nodding until mature. They are composed of yellow to yellow-orange strap-shaped flowers. The flowers are enclosed within a 6-15 millimetres (mm) tall involucre of broadly lanceolate bracts, often reddish on the outer surface and long black-hairy within. The fruits are brown to bronze, sometimes darkly spotted achenes. The achenes are 2.5-6 mm long and abruptly tapered at the base; they are crowned by a pappus of five hairless or short-hairy scales, each terminating in a long, hair-like bristle arising from the pointed scale (Douglas et al. 1998). There are no similar species within its extent of occurrence which might be mistaken for Coast Microseris.

Genetic description

Microseris bigelovii has a chromosome count of 2n=18 (Chambers 1993). Heusden and Bachmann (1992) examined genetic characteristics of material grown from seed collected at Saxe Point and Cattle Point. They found the plants at both of these sites had a chloroplast mutation only known from one other population (from San Mateo County, south of San Francisco). Grown in a greenhouse, plants derived from British Columbia populations flowered almost two months later than those from the southern-most California populations and possessed distinctive leaf morphologies (Bachmann et al. 1987).

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