Triniteurybia
Sida 21: 898. 2004.
| Taxon | Illustrator ⠉ | |
|---|---|---|
 | Eurybia hemispherica Triniteurybia aberrans Xanthisma texanum var. drummondii | Yevonn Wilson-Ramsey Linny Heagy Yevonn Wilson-Ramsey |
Perennials, 5–25 (–30) cm (cespitose; caudices woody, ramified, from slender creeping taproots). Stems erect, simple, slender, stipitate-glandular. Leaves basal and cauline; alternate; basal (mostly persistent) petiolate to subsessile, distal sessile; blades 1-nerved, obovate or oblong to broadly oblanceolate margins sparsely spinulose-serrate, faces stipitate-glandular. Heads discoid, borne singly or 2–4 in dense, ± corymbiform arrays. Involucres cylindro-campanulate, 9–14 mm wide. Phyllaries ca. 30 in 3–4 series, 1-nerved (keeled), lance-oblong to lanceolate (outer) to linear-lanceolate (inner), unequal, bases indurate, distal green zones ± basally truncate to diamond-shaped, occupying distal 1/3, faces glandular-viscid. Receptacles slightly convex, pitted, epaleate. Ray-florets 0. Disc-florets 25–50, bisexual, fertile; corollas yellow and often reddish (particularly lobes), barely ampliate, tubes shorter than slenderly cylindric throats, lobes 5, erect, lanceolate (minutely and sparsely puberulent); style-branch appendages lanceolate. Cypselae fusiform, ± 3 mm, ± 10-nerved, faces densely white strigoso-hirsute, eglandular; pappi persistent, of 20–35, unequal, barbellulate, stramineous, some apically ± clavate bristles in (1–) 2 series. x = 9.
Distribution
nw United States
Discussion
Species 1.
Originally described as a Macronema species, Triniteurybia aberrans was treated by H. M. Hall (1928) in Haplopappus sect. Tonestus on the basis of habit and foliage, though style branches indicated affinities to sect. Macronema. After disposal of other members of Haplopappus in segregate genera, G. L. Nesom and D. R. Morgan (1990) placed the species in Tonestus on the basis of its herbaceous habit, long-stipitate glands, well-developed, coarsely dentate cauline leaves, few heads, and 1-nerved phyllaries, all characteristics also found in the eurybioid complex. Molecular phylogenetic data (L. Brouillet et al. 2004) indicate that this species belongs to the eurybioid complex (J. C. Semple et al. 2002), as sister to the Machaerantherinae. The cylindro-campanulate heads with imbricate phyllaries and a wide green area, and the coarse, dentate foliage, are similar to those of Eurybia. The lack of ray florets clearly distinguishes Triniteurybia.
Selected References
None.