Gutierrezia texana

(de Candolle) Torrey & A. Gray

Fl. N. Amer. 2: 194. 1842.

Common names: Texas snakeweed
Basionym: Hemiachyris texana de Candolle in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 5: 314. 1836
Synonyms: Xanthocephalum texanum (de Candolle) Shinners
Treatment appears in FNA Volume 20. Treatment on page 91. Mentioned on page 89.

Annuals, 10–80 (–100) cm. Stems glabrous. Leaves: proximal usually absent at flowering; cauline blades 1-nerved or 3-nerved, linear, 1.5–4 mm wide, reduced distally. Heads in loose arrays. Involucres campanulate to obconic, 2–4.5 mm diam.. Phyllary apices flat. Ray-florets 5–23; corollas yellow, 3–6 mm. Disc-florets 7–48 (bisexual and fertile or functionally staminate). Cypselae 1.3–1.8 mm, faces without oil cavities, loosely strigose (hairs appressed, apices acute, microscopically 2-pronged); pappi of 1 series of spreading-erect, oblong to ovate or obovate scales 0.1–0.5 mm (bases sometimes connate, usually shorter in rays, sometimes 0 in var. texana).

Distribution

V20-173-distribution-map.gif

Ark., Ill., La., Mo., N.Mex., Okla., Tex., Mexico

Discussion

Varieties 2 (2 in the flora).

Although the two varieties of Gutierrezia texana are similar, the geographic demarcation between them appears to be sharp, and a detailed investigation of their biologic interaction would be interesting.

Selected References

None.

Key

1 Involucres (2–)3.5–4.5 mm diam.; disc florets 10–48; cypselae moderately to densely strigoso-sericeous, hairs usually in dense lines and at least partially obscuring faces; pappi of distinct scales 0.2–0.5 mm, rarely more reduced Gutierrezia texana var. glutinosa
1 Involucres 2–3 mm diam.; disc florets 7–13; cypselae sparsely and evenly strigose, hairs not obscuring cypsela faces; pappi of continuous or scaly crowns less than 0.1 mm Gutierrezia texana var. texana

"[" is not declared as a valid unit of measurement for this property."]" is not declared as a valid unit of measurement for this property.

... more about "Gutierrezia texana"
hirtellous +, hispidulous +  and glabrous +
not tailed +, rounded +  and obtuse +
distinct +
subequal +
scarious +
usually triangular +  and linear +
usually deltate +  and lanceolate +
spiciform +, racemiform +, paniculiform +  and corymbiform +
indeterminate +  and determinate +
Guy L. Nesom +
(de Candolle) Torrey & A. Gray +
decurrent +
white-indurate +
Hemiachyris texana +
compound +  and simple +
linear;lanceolate or spatulate +
rugulose +  and muricate +
barbellulate +  and barbellate +
3-nerved +  and 1-nerved +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
Texas snakeweed +
not 2-lipped +  and actinomorphic +
0.3 cm3 mm <br />0.003 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
beaked +, 2-ribbed +  and 5-ribbed +
not compressed +, cylindric +  and clavate +
fertile +  and bisexual +
fertile +  and bisexual +
Ark. +, Ill. +, La. +, Mo. +, N.Mex. +, Okla. +, Tex. +  and Mexico +
resinous +
gland-dotted +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
indeterminate +
heterogamous +  and homogamous +
each +  and sessile +
0.2 cm2 mm <br />0.002 m <br /> (0.45 cm4.5 mm <br />0.0045 m <br />) +
campanulate;obconic +
petiolate +  and sessile +
cauline +  and basal +
short-deltate +
2-carpellate +
erose-margined +
persistent +
of 5-10 whitish +  and coroniform +
3-nerved +  and 1-nerved +
ovate +  and lanceolate +
Fl. N. Amer. +
bearing subulate enations +, hairy +  and bristly +
spreading-erect +
oblong +  and ovate or obovate +
exalbuminous +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
erect +  and ascending +
appendaged +  and truncate +
papillate +  and smooth +
Xanthocephalum texanum +
Gutierrezia texana +
Gutierrezia +
species +
80 cm800 mm <br />0.8 m <br /> (100 cm1,000 mm <br />1 m <br />) +
10 cm100 mm <br />0.1 m <br /> (80 cm800 mm <br />0.8 m <br />) +