Gutierrezia sphaerocephala |
Gutierrezia microcephala |
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round-leaf snakeweed |
small-head snakeweed, sticky snakeweed, threadleaf snakeweed |
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Habit | Annuals, 20–50 cm. | Subshrubs, 20–140 cm. |
Stems | minutely, prominently, often sparsely, papillate-scabrous (hairs triangular or deltate to lanceolate, less than 0.1 mm). |
glabrous or minutely hispidulous. |
Leaves | proximal usually absent at flowering; cauline blades 1-nerved, linear, 0.5–1.2 mm wide, little reduced distally. |
basal and proximal absent at flowering; cauline blades 1-nerved, linear or filiform to narrowly oblanceolate or lanceolate, 0.5–2.2(–4) mm wide, little reduced distally. |
Involucres | campanulate, 2.5–5 mm diam. |
cylindric, 1–1.5 mm diam. |
Ray florets | 10–15; corollas yellow, 3–5.5 mm. |
1(–2; each enclosed by conduplicate inner phyllary); corollas yellow, (1.5–)2–3.5 mm. |
Disc florets | 18–37. |
1, sometimes 2 (functionally staminate; corollas broadly obdeltate-funnelform, throats widely flaring, lobes 1/3 corolla lengths, recurved-coiling). |
Heads | in loose arrays. |
(2–6, sessile to subsessile, in compact glomerules) in flat-topped arrays. |
Cypselae | 0.9–1.2(–1.4) mm, faces without oil cavities, densely strigoso-sericeous in rows (hairs appressed to spreading, apices clavate); pappi of 1 series of narrowly triangular or narrowly oblong scales 0.2–1 mm (distinct or basally connate 1/4–3/4 their lengths, usually shorter in rays). |
1–1.8(–2.5) mm, faces densely strigoso-sericeous; pappi (rays, readily falling) of 1 series of narrowly lanceolate-oblong scales. |
Phyllary | apices flat. |
apices flat. |
2n | = 8 (10). |
= 8, 16, 24, 32. |
Gutierrezia sphaerocephala |
Gutierrezia microcephala |
|
Phenology | Flowering (Feb–)May–Dec. | Flowering (Jun–)Jul–Dec(–Feb). |
Habitat | Grasslands, roadsides, lake edges, alkaline flats with Atriplex, oak-pine-juniper woodlands, often over gypsum or limestone | Grasslands, chaparral, oak or oak-pine woodlands, usually over gravelly or rocky limestone or gypsum substrates, dunes |
Elevation | (200–)1300–2000 m ((700–)4300–6600 ft) | 800–2500 m (2600–8200 ft) |
Distribution |
AZ; NM; TX; Mexico (Chihuahua, Coahuila, Durango, Nuevo León, San Luis Potosí, Tamaulipas, Zacatecas)
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AZ; CA; CO; NM; NV; TX; UT; Mexico (Baja California, Chihuahua, Coahuila, Durango, Nuevo León, San Luis Potosí, Sonora, Tamaulipas, Veracruz, Zacatecas)
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Discussion | Gutierrezia microcephala is recognized by its perennial habit and its small, tightly clustered heads, each with 4–8 phyllaries and 1(–2) ray and disc florets. Each ray floret is enclosed by a conduplicate inner phyllary. Forms of G. sarothrae with few florets in each head can be distinguished by their bisexual and fertile disc florets and tubular-funnelform disc corollas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 20, p. 92. | FNA vol. 20, p. 92. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | G. eriocarpa, Xanthocephalum sphaerocephalum, Xanthocephalum sphaerocephalum var. eriocarpum | Brachyris microcephala, G. sarothrae var. microcephala, Xanthocephalum microcephalum |
Name authority | A. Gray: Mem. Amer. Acad. Arts, n. s. 4: 73. (1849) | (de Candolle) A. Gray: Mem. Amer. Acad. Arts, n. s. 4: 74. (1849) |
Web links |