Thymophylla pentachaeta

(de Candolle) Small

Fl. S.E. U.S., 1295, 1341. 1903.

Basionym: Hymenatherum pentachaetum de Candolle in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 5: 642. 1836
Synonyms: Dyssodia pentachaeta (de Candolle) B. L. Robinson
Treatment appears in FNA Volume 21. Treatment on page 241. Mentioned on page 240.

Perennials or subshrubs, ± grayish to green, to 15(–25) cm, usually puberulent to canescent, sometimes glabrescent or glabrous. Stems erect or spreading. Leaves mostly opposite; blades mostly pinnately lobed, 6–28+ mm overall, lobes 3–11 linear to filiform (usually stiff, setiform). Peduncles 20–100 mm, puberulent or glabrous. Calyculi 0, or of 1–5 deltate bractlets, lengths less than 1/2 phyllaries. Involucres obconic to campanulate or hemispheric, 4–6 mm. Phyllaries 12–21, margins of outer distinct 1/5 to nearly all their lengths, abaxial faces puberulent or glabrous. Ray florets (8–)12–21; corollas yellow to orange-yellow, laminae 2–6(–8) × 1–3 mm. Disc florets 16–40 or 50–80; corollas yellow, 2–4 mm (tending to zygomorphy in peripheral florets in some plants). Cypselae 2–3 mm; pappi of 10 erose and/or aristate scales mostly 1–3 mm.



Ariz., Calif., N.Mex., Nev., Tex., Utah, Mexico, introduced(?) in South America (Argentina).


Varieties 4 (4 in the flora).

Selected References



1 Involucres cylindric, 2–3.5 mm diam.; disc florets 16–40 Thymophylla pentachaeta var. hartwegii
1 Involucres obconic, campanulate, or hemispheric, mostly 4–5 mm diam.; disc florets 50–80 > 2
2 Peduncles 20–50 mm; margins of outer phyllaries distinct almost to bases Thymophylla pentachaeta var. belenidium
2 Peduncles (40–)50–100 mm; margins of outer phyllaries distinct less ca. 1/2 or ca. 1/3 their lengths > 3
3 Leaf lobes mostly 9–11; phyllaries usually glabrous or glabrescent, rarely hairy Thymophylla pentachaeta var. pentachaeta
3 Leaf lobes mostly 5–7(–10); phyllaries densely puberulent Thymophylla pentachaeta var. puberula