Difference between revisions of "Gutierrezia texana"

(de Candolle) Torrey & A. Gray

Fl. N. Amer. 2: 194. 1842

Common names: Texas snakeweed
Basionyms: 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.
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|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 3b. Gutierrezia texana var. texana
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|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
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|[[Gutierrezia texana var. texana|Gutierrezia texana var. texana]]
 
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Latest revision as of 19:10, 26 November 2019

Annuals, 10–80(–100) cm. Stems glabrous. Leaves: proximal usually absent at flowering; cauline blades 1- 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 </i>var.<i> texana).

Distribution

V20-173-distribution-map.gif

s, sc United States, 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.

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