Flora of North America species comparison

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Madia exigua

little tarplant, little tarweed, small tarweed, thread-stem madia
Habit Plants 1–30(–50) cm, self-compatible (heads not showy).
Stems

hirsute and glandular-pubescent, glands yellowish or purple, lateral branches seldom surpassing main stems.
Leaf

blades linear, 0.2–4 cm × 0.5–2 mm.
Involucres

depressed-globose, 2.5–5 mm.
Ray florets

1–8;

corollas pale yellow, laminae 0.7–1 mm.
Disc florets

1(–2), bisexual, fertile;

corollas 1–1.8 mm, glabrous;

anthers yellow to brownish.
Phyllaries

± hirsute and glandular-pubescent as well, glands golden yellow, apices ± erect, sulcate.
Heads

in open, corymbiform arrays (peduncles ± filiform).
Disc cypselae

obovoid, weakly compressed.
Ray cypselae

black or brown, dull, compressed (strongly arcuate), beaked (beaks adaxially offset, curved).
Paleae

mostly persistent, connate 1/2+ their lengths.
2n

= 32.

Madia exigua
Phenology Flowering Apr–Jul.
Habitat Openings in grasslands, meadows, shrublands, woodlands, and forests, disturbed sites, often sandy, gravelly, or clayey soils, sometimes serpentine
Elevation 30–2500 m (100–8200 ft)
Distribution
from FNA
CA; ID; MT; NV; OR; WA; BC; Mexico (Baja California)
[WildflowerSearch map]
[BONAP county map]
Discussion

Madia exigua occurs in seasonally dry situations in much of western North America outside the warm deserts. Morphologically, M. exigua is somewhat similar to Hemizonella minima, which (unlike M. exigua) has subumbellate arrays of heads and obcompressed, sparsely hairy ray cypselae.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 21, p. 306.
Parent taxa Asteraceae > tribe Heliantheae > subtribe Madiinae > Madia
Sibling taxa
M. anomala, M. citrigracilis, M. citriodora, M. elegans, M. glomerata, M. gracilis, M. radiata, M. sativa, M. subspicata
Synonyms Sclerocarpus exigua
Name authority (Smith) A. Gray: Proc. Amer. Acad. Arts 8: 391. (1872)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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