Bidens tenuisecta

A. Gray

Mem. Amer. Acad. Arts, n. s. 4: 86. 1849

Treatment appears in FNA Volume 21. Treatment on page 210. Mentioned on page 207.
Annuals, (10–)20–40 cm. Leaves: petioles 5–40 mm; blades rounded-deltate to ovate overall, 20–50+ × 15–35+ mm, (1–)2–3-pinnatisect, ultimate lobes ± linear, (2–)5–15+ × (0.5–)2–3+ mm, bases ± cuneate, ultimate margins entire, sometimes ciliolate, apices acute to attenuate, faces usually glabrous, sometimes hispidulous. Heads usually borne singly, sometimes in 2s or 3s. Peduncles 20–30(–80) mm. Calyculi of 6–12 ± appressed, linear bractlets 5–7 mm, margins scabro-ciliate, abaxial faces usually pilosulous to hirsutulous, rarely glabrous. Involucres campanulate to hemispheric or broader, (5–)6–7 × 4–8 mm. Phyllaries 8, lance-linear, 5–7 mm. Ray florets 0 or 3–6; laminae yellow, 4–6 mm. Disc florets (5–)12–20(–45); corollas yellow, 2–3 mm. Cypselae: outer red-brown, flat or weakly 4-angled, linear, 6–8 mm, margins not ciliate, apices somewhat attenuate, faces obscurely 2-grooved, often tuberculate, glabrous or ± strigillose; inner similar, blackish (sometimes with pale tips), ± equally 4-angled, linear-fusiform, 8–15 mm, margins not ciliate, apices attenuate, faces 2-grooved, glabrous or, toward tips, strigillose; pappi of 2(–3), spreading to divergent, retrorsely barbed awns (1–)1.5–3 mm.

Phenology: Flowering (Jul–)Aug–Sep(–Oct).
Habitat: Meadows, along streams
Elevation: 1800–2600 m

Distribution

V21-510-distribution-map.gif

Ariz., Colo., Idaho, N.Mex., Utah, Mexico (Chihuahua).

Discussion

Reports of Bidens tenuisecta from Maryland, Massachusetts, and New York may be based on ephemeral introductions.

References

None.

Lower Taxa

No lower taxa listed.