Tetradymia axillaris
Tetradymia
catclaw horsebrush, cottonthorn, longspine horsebrush
cottonthorn, horse-brush
1–5+, erect or spreading, spiny, evenly pannose.
1–5+, erect to spreading (tomentose to pannose or glabrous, often spiny).
primaries forming straight, ± squarrose spines, 10–50 mm;
secondaries filiform to clavate, 2–12(–20) mm, sparsely arachnose or glabrous.
(usually with fascicles of secondary leaves in axils of the primary; primaries sometimes becoming spines) cauline; alternate;
sessile (or obscurely petiolate);
blades obscurely palmately nerved (usually 1-nerved), linear to filiform, narrowly lanceolate, or oblanceolate, margins entire, faces glabrous or lanate to tomentose, sometimes glabrescent.
4–15 mm.
turbinate to campanulate, 7–9 mm.
turbinate to cylindric or hemispheric, 3–10+ mm diam.
flat, foveolate, epaleate.
5–7;
corollas pale yellow, 7.5–9 mm.
0.
4–9, bisexual, fertile;
corollas cream to bright yellow, tubes longer than funnelform or abruptly dilated throats, lobes 5, recurved, linear to lanceolate;
style branches stigmatic in 2 lines, apices usually truncate to rounded-truncate, sometimes truncate-penicillate (appendages essentially 0).
5, ovate.
persistent, 4–6 in 1–2 series, erect, distinct, mostly oblong to ovate or lanceolate, equal or subequal, margins obscurely scarious.
0.
1–3 (in axils of spines).
discoid, (1–3) in distil axils or (3–8) in corymbiform clusters.
4.5–5.5 mm, densely pilose (hairs 6–14 mm);
pappi of ca. 25, subulate to setiform scales 6–7.5 mm.
prismatic to obconic or fusiform, obscurely 5-ribbed, glabrous or hirsute to densely pilose (hairs often obscuring pappi);
pappi 0 or of 70–150 bristles or of 20–30, white to stramineous, subulate to setiform scales.
= 30.
Tetradymia axillaris
Tetradymia
Varieties 2 (2 in the flora).
The two varieties of Tetradymia axillaris are partially sympatric and intergrade in areas of overlap.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species 10 (10 in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Peduncles and phyllaries pannose to tomentose; hairs of cypselae 9–14 mm | var. longispina |
1. Peduncles and phyllaries glabrous; hairs of cypselae 6–8(–10) mm | var. axillaris |
1. Indumentum of stems evenly pannose; cypselae with white hairs that obscure or replace pappi; pappi 0 or of 20–30, subulate to setiform scales | → 2 |
1. Indumentum of stems interrupted by linear, tomentose to nearly glabrous streaks; cypselae glabrous or with induments shorter than cypselae, not obscuring or replacing pappi; pappi of 70–150 bristles | → 5 |
2. Primary leaves forming rigid spines; heads in clusters of 1–3 (in axils of spines) | → 3 |
2. Primary leaves flaccid or stiff and pungent, not forming spines; heads in corymbiform clusters of 3–7 | → 4 |
3. Spines straight, 10–50 mm, glabrescent; involucres mostly turbinate, 7–9 mm; cypselae 4–5 mm | T. axillaris |
3. Spines recurved, 5–25 mm, tomentose; involucres mostly campanulate, 8–12 mm; cypselae 6–8 mm | T. spinosa |
4. Blades of primary leaves lance-linear to spatulate, becoming stiff, pungent; florets 5–8; cypselae 6–8 mm, epappose | T. comosa |
4. Blades of primary leaves filiform, flaccid; florets 4(–5); cypselae 4–6 mm, pappose | T. tetrameres |
5. Primary leaves not forming spines | → 6 |
5. Primary leaves becoming rigid, ± persistent spines | → 8 |
6. Blades of primary leaves subulate and ± appressed to stems, contrasting with subtended clavate, glabrous or glabrescent blades of secondary leaves | T. glabrata |
6. Blades of primary leaves filiform to spatulate, spreading, similar to subtended tomentose to sericeous blades of secondary leaves | → 7 |
7. Blades of primary leaves spatulate to lanceolate; pappus bristles weakly, if at all, distally dilated | T. canescens |
7. Blades of primary leaves linear to filiform; pappus bristles distally dilated | T. filifolia |
8. Blades of secondary leaves filiform to clavate; cypselae glabrous | T. argyraea |
8. Blades of secondary leaves spatulate; cypselae densely hirsute or villous to densely pilose | → 9 |
9. Blades of secondary leaves greenish, usually villous, sometimes glabrescent; florets mostly 4; cypselae 4–6 mm, densely hirsute | T. nuttallii |
9. Blades of secondary leaves silvery sericeous; florets mostly 5; cypselae 6–8 mm, villous to densely pilose | T. stenolepis |
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