E-Flora BC: Electronic Atlas of the Flora of British Columbia

Madia exigua (Sm.) A. Gray
little tarweed (small tarweed)
Asteraceae (Aster family)

Introduction to Vascular Plants

© Hans Roemer  Email the photographer   (Photo ID #26143)

E-Flora BC Static Map
Distribution of Madia exigua
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Species Information

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Aromatic annual herb from a slender taproot; stems erect, simple, branched above, stiff-hairy, 5-30 cm tall.
Basal leaves lacking; stem leaves alternate, simple, entire, linear, 1-4 cm long, 1-2 mm wide, glandular, stiff-hairy.
Heads with ray and disk flowers, solitary at the ends of branches in an open, flat-topped inflorescence; involucres depressed-globose, 2.5-4.5 mm tall; involucral bracts linear dorsally, crescent shaped laterally, 4-8, glandular; ray flowers yellow, 4-8, 1 mm long; disk flower yellow, receptacular bracts united around the fertile disk flower.
Achenes compressed, 1.8-2.8 mm long, dark brown or black; disk achenes sterile; pappus lacking.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Dry grasslands, roadsides and disturbed areas in the lowland, steppe and lower montane zones; frequent in extreme S BC; S to NV, CA and MX.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Madia exigua

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class




Elevation (metres) 550 770 1168
Slope Gradient (%) 0 35 80
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
60 156 240
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
0 1 3
Modal Nutrient Regime
Number of field plots
 species was recorded in:
Modal BEC Zone Class
All BEC Zones (# of stations/zone) species was recorded in: MS(1), PP(4)


The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References