treatments/TRIXIS

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TRIXIS P. Browne Civ. Nat. Hist. Jamaica,. 312, plate 33, fig. 1. 1756.

Threefold [Greek trixos , 3-fold, describing the 3-cleft corolla]

David J. Keil,

Shrubs [herbs], 20–300+ cm (often rhizomatous, stems hairy, hairs gland-tipped and glandless). Leaves cauline; sessile or petiolate; blades elliptic, lanceolate, linear, or linear-lanceolate, bases cuneate, margins dentate or entire, faces (at least abaxial) usually glandular and ± strigose. Heads quasi-radiate (see florets), borne singly or in corymbiform or paniculiform arrays. Involucres ± cylindric, 12–15 mm (subtended by calyculi of 3–7 spreading or ascending bractlets). Phyllaries (reflexed in fruit) in 1–2 series, linear (± keeled), apices acute. Receptacles flat, smooth, hairy, epaleate. Florets 4–25[–60], bisexual, fertile; corollas yellow (aging white), zygomorphic (2-lipped; outer lip liguliform, lobes 3, lance-deltate, inner lip smaller, lobes ± filiform, recurved); anther basal appendages entire, apical appendages oblong, acute; style branches relatively short, apices truncate-penicillate. Cypselae subcylindric to fusiform, often ± beaked, ribs 5, faces glandular-hairy; pappi of 60–80+ dull white [tawny], finely barbed bristles. x = 9.


Species ca. 65 (2 in the flora):North America; Mexico; West Indies; Central America; South America.;


SELECTED REFERENCES
Anderson, C. E. 1972. A monograph of the Mexican and Central American species of Trixis (Compositae). Mem. New York Bot. Gard. 22(3): 1–68.


1. Leaves usually ascending, almost parallel with stems, stomates on both faces, induments: abaxial faces glandular and sparsely strigose (sometimes only on veins), adaxial faces glandular and strigose to pilose; papilla-like double hairs of cypselae producing mucilage when wetted 1. Trixis californica
1. Leaves usually spreading, stomates on abaxial faces, induments: margins and, sometimes, abaxial midveins with glandless and glandular hairs, otherwise glabrous; papilla-like double hairs of cypselae not producing mucilage when wetted 2. Trixis inula