Xanthocephalum gymnospermoides

(A. Gray) Bentham & Hooker f.

Gen. Pl. 2: 249. 1873.

Common names: San Pedro matchweed
Illustrated
Basionym: Gutierrezia gymnospermoides A. Gray Smithsonian Contr. Knowl. 5(6): 79. 1853
Synonyms: Grindelia gymnospermoides (A. Gray) Ruffin
Treatment appears in FNA Volume 20. Treatment on page 437.

Plants 30–150 cm, herbage glabrous. Stems usually 1, erect. Leaf-blades 40–100 mm, bases narrowly decurrent, margins entire to spinulose-toothed, faces resinous. Heads usually in tight to loose, corymbiform arrays, rarely borne singly. Peduncles: ultimate 1–40 mm, minutely stipitate-glandular. Phyllaries minutely stipitate-glandular. Ray corollas 4–11 mm. Pappi (ray) 0, outer disc 0 or minute crowns, inner nearly 0 or minute crowns, sometimes lacerate or with awnlike scales 0.2–0.8 mm, rarely with ring of persistent, 15–20, antrorsely ciliolate bristles ca. 1.4 mm. 2n = 12.


Phenology: Flowering (Jul–)Aug–Oct.
Habitat: Meadows, stream bottoms, ditches, grasslands, areas of oak-pine or pine woodlands, usually in habitats at least intermittently wet
Elevation: 1100–2700 m

Distribution

V20-1000-distribution-map.gif

Ariz., Tex., Mexico (Chihuahua), Mexico (Durango), Mexico (Jalisco), Mexico (Sonora), Mexico (Zacatecas)

Discussion

Selected References

None.

Lower Taxa

None.
not tailed +, rounded +  and obtuse +
distinct +
subequal +
scarious +
usually triangular +  and linear +
usually deltate +  and lanceolate +
indeterminate +  and determinate +
Guy L. Nesom +
(A. Gray) Bentham & Hooker f. +
decurrent +
Gutierrezia gymnospermoides +
4 cm40 mm <br />0.04 m <br /> (10 cm100 mm <br />0.1 m <br />) +
oblanceolate +
rugulose +  and muricate +
barbellulate +  and barbellate +
San Pedro matchweed +
not 2-lipped +  and actinomorphic +
yellow +  and orange-yellow +
ampliate +
lacerate +
beaked +, 2-ribbed +  and 5-ribbed +
compressed +, irregularly ovoid +  and oblong +
fertile +  and bisexual +
fertile +  and bisexual +
Ariz. +, Tex. +, Mexico (Chihuahua) +, Mexico (Durango) +, Mexico (Jalisco) +, Mexico (Sonora) +  and Mexico (Zacatecas) +
rounded +
1100–2700 m +
resinous +
gland-dotted +
strigillose +, glabrous +  and glandular +
turgid;cylindric +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Meadows, stream bottoms, ditches, grasslands, areas of oak-pine or pine woodlands, usually in habitats at least intermittently wet +
indeterminate +
heterogamous +  and homogamous +
each +  and sessile +
0.4 cm4 mm <br />0.004 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
0.7 cm7 mm <br />0.007 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
0.23 cm2.3 mm <br />0.0023 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
campanulate +
0.5 cm5 mm <br />0.005 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
triangular-lanceolate +
dentate to pinnatifid +  and entire +
entire +  and spinulose-toothed +
with awnlike scales +  and lacerate +
2-carpellate +
persistent +
stipitate-glandular +
0.1 cm1 mm <br />0.001 m <br /> (4 cm40 mm <br />0.04 m <br />) +
Flowering (Jul–)Aug–Oct. +
stipitate-glandular +
0.4 cm4 mm <br />0.004 m <br /> (1.1 cm11 mm <br />0.011 m <br />) +
bearing subulate enations +, hairy +  and bristly +
pitted to smooth +  and pitted +
prominent +
strigillose +  and glabrous +
turgid +  and cylindric +
awnlike +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.08 cm0.8 mm <br />8.0e-4 m <br />) +
exalbuminous +
Illustrated +
branched +  and simple +
resinous +
appendaged +  and truncate +
papillate +  and smooth +
Grindelia gymnospermoides +
Xanthocephalum gymnospermoides +
Xanthocephalum +
species +
ovatelanceolate +
unequal +
white-indurate +
slightly longer +
2 cm20 mm <br />0.02 m <br /> (200 cm2,000 mm <br />2 m <br />) +