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

Nuttall's horsebrush

Habit Shrubs, 10–100 cm. Shrubs, 10–120 cm.
Stems

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

1–5+, erect, spiny, pannose but for glabrescent streaks.

Leaves

primaries forming recurved spines, 5–25 mm;

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

primaries forming straight or recurved spines, 5–25 mm;

secondaries spatulate, 10–20 mm, tomentose to nearly glabrous.

Peduncles

5–30 mm.

2–12 mm.

Involucres

hemispheric, 8–12 mm.

turbinate to cylindric, 6–9 mm.

Florets

5–8;

corollas pale to bright yellow, 6–10 mm.

4;

corollas bright yellow, 8–10 mm.

Phyllaries

4–6, oblong to ovate.

4, oblong.

Heads

1–2 (in axils of spines).

4–6.

Cypselae

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

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

4–6 mm, densely hirsute;

pappi of 75–100 bristles 9–10 mm.

2n

= 60.

= 60.

Tetradymia spinosa

Tetradymia nuttallii

Phenology Flowering spring. Flowering spring–summer.
Habitat Usually sandy soils of alkali sinks, shadscale scrub, pinyon-juniper woodlands Rocky or sandy places, sagebrush scrub or shadscale scrub
Elevation 800–2400 m (2600–7900 ft) 1300–2100 m (4300–6900 ft)
Distribution
from FNA
CA; CO; ID; MT; NM; NV; OR; UT; WY
[WildflowerSearch map]
[BONAP county map]
from FNA
NV; UT; WY
[WildflowerSearch map]
[BONAP county map]
Source FNA vol. 20, p. 632. FNA vol. 20, p. 631.
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. filifolia, T. glabrata, T. spinosa, T. stenolepis, T. tetrameres
Name authority Hooker & Arnott: Bot. Beechey Voy., 360. (1839) Torrey & A. Gray: Fl. N. Amer. 2: 447. (1843)
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