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catclaw horsebrush, cotton-thorn horsebrush, shortspine horsebrush, spiny horsebrush

threadleaf horsebrush

Habit Shrubs, 10–100 cm. Shrubs, 1–5+ dm.
Stems

1–5+, erect or spreading, spiny, evenly pannose.

1–5+, erect, unarmed, tomentose to glabrescent.

Leaves

primaries forming recurved spines, 5–25 mm;

secondaries linear-filiform to spatulate, 3–25 (× 1–2) mm, glabrous or glabrescent.

primaries linear-subulate, 5–20+ mm, floccose, sometimes glabrate;

secondaries linear-filiform, 3–15 mm.

Peduncles

5–30 mm.

3–15 mm.

Involucres

hemispheric, 8–12 mm.

turbinate, 7–10 mm.

Florets

5–8;

corollas pale to bright yellow, 6–10 mm.

4;

corollas cream to bright yellow, 9–10 mm.

Phyllaries

4–6, oblong to ovate.

4, lanceolate to obovate.

Heads

1–2 (in axils of spines).

3–7.

Cypselae

6–8 mm, copiously pilose (hairs 9–12 mm);

pappi of ca. 25, subulate scales 6–9 mm.

3–5 mm, hirsute;

pappi of 100–130 (distally dilated) bristles 6–8 mm.

2n

= 60.

= 120.

Tetradymia spinosa

Tetradymia filifolia

Phenology Flowering spring. Flowering summer.
Habitat Usually sandy soils of alkali sinks, shadscale scrub, pinyon-juniper woodlands Pinyon-juniper woodlands, sometimes gypseous soils
Elevation 800–2400 m (2600–7900 ft) 1500–1800 m (4900–5900 ft)
Distribution
from FNA
CA; CO; ID; MT; NM; NV; OR; UT; WY
[WildflowerSearch map]
[BONAP county map]
from FNA
NM
[BONAP county map]
Source FNA vol. 20, p. 632. FNA vol. 20, p. 630.
Parent taxa Asteraceae > tribe Senecioneae > Tetradymia Asteraceae > tribe Senecioneae > Tetradymia
Sibling taxa
T. argyraea, T. axillaris, T. canescens, T. comosa, T. filifolia, T. glabrata, T. nuttallii, T. stenolepis, T. tetrameres
T. argyraea, T. axillaris, T. canescens, T. comosa, T. glabrata, T. nuttallii, T. spinosa, T. stenolepis, T. tetrameres
Name authority Hooker & Arnott: Bot. Beechey Voy., 360. (1839) Greene: Bull. Torrey Bot. Club 25: 123, plate 334, figs. 3, 4. (1898)
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