treatments/Stephanomeria exigua

From Botanical Knowledge
Jump to: navigation, search


Stephanomeria exigua Nuttall Trans. Amer. Philos. Soc., n. s.. 7: 428. 1841.

Small wirelettuce


Annuals, 10–200 cm (taproots relatively large). Stems single, branches divaricately or freely spreading, glabrous or sparsely pubescent. Leaves withered at flowering; basal blades linear to oblanceolate, runcinate, 3–10 cm, margins pinnately lobed; cauline much reduced, bractlike. Heads borne singly or clustered along branches or in paniculiform arrays. Peduncles 2–10 mm (along branches), or 10–40 mm (in paniculiform arrays). Calyculi of appressed or reflexed bractlets (glabrous, pubescent, or stipitate-glandular). Involucres 5–7 mm (glabrous, puberulent, or densely stipitate-glandular). Florets 5–11. Cypselae light tan to dark brown, 2.1–6.8 mm, faces smooth to tuberculate, grooved; pappi of 5–24 tan or white bristles (falling or widened bases persistent, bases connate in groups of 2–4 distal portions breaking off), plumose on distal 50–85%. 2n = 16.


Subspecies 5 (5 in the flora):w United States; nw Mexico.;



1. Heads borne singly or clustered along branches; peduncles 2–10 mm. (2.)
2. Calyculus bractlets appressed; peduncles 2–5 mm 4b. Stephanomeria exigua subsp. coronaria
2. Calyculus bractlets reflexed; peduncles 5–10 mm 4e. Stephanomeria exiguasubsp. macrocarpa
1. Heads in paniculiform arrays; peduncles 10–40 mm. (3.)
3. Calyculus bractlets reflexed 4a. Stephanomeria exigua subsp. carotifera
3. Calyculus bractlets appressed. (4.)
4. Peduncles and involucres densely glandular 4c. Stephanomeria exigua subsp. deanei
4. Peduncles and involucres glabrous or sparsely glandular 4d. Stephanomeria exigua subsp. exigua