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round-leaf snakeweed

small-head snakeweed, sticky snakeweed, threadleaf snakeweed

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
from FNA
AZ; NM; TX; Mexico (Chihuahua, Coahuila, Durango, Nuevo León, San Luis Potosí, Tamaulipas, Zacatecas)
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; CO; NM; NV; TX; UT; Mexico (Baja California, Chihuahua, Coahuila, Durango, Nuevo León, San Luis Potosí, Sonora, Tamaulipas, Veracruz, Zacatecas)
[WildflowerSearch map]
[BONAP county map]
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.)

Source FNA vol. 20, p. 92. FNA vol. 20, p. 92.
Parent taxa Asteraceae > tribe Astereae > Gutierrezia Asteraceae > tribe Astereae > Gutierrezia
Sibling taxa
G. arizonica, G. californica, G. microcephala, G. petradoria, G. pomariensis, G. sarothrae, G. serotina, G. texana, G. wrightii
G. arizonica, G. californica, G. petradoria, G. pomariensis, G. sarothrae, G. serotina, G. sphaerocephala, G. texana, G. wrightii
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)
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