Texas snake-cotton

Froelichia interrupta (Linnaeus) Moquin-Tandon var. cordata Uline & W. L. Bray

Plants perennial; taproot en-larged, woody. Stems 1-several, ascending or decumbent, simple or branched, 3-10 dm, thinly grayish white-tomentose. Leaves sessile or short-petiolate; blade ovate-orbiculate or short-lanceolate, proximal leaves 2.5-3.5-12 × 1-4.8 cm, base attenuate to rounded or obtuse, apex obtuse to acute, floccose-tomentose with grayish white hairs abaxially, sparsely canescent adaxially. Spikes lax, flowers arranged in 5-ranked spiral; bracteoles stramineous or light brown, glabrous. Flowers 3-4.6 mm; tepals narrowly oblong, apex obtuse or acutish, pubescence of mature flowers sparse, dull; pseudostaminodes darkened, apex blunt. Fruting perianth broadly winged laterally, 3.2-4.6 × 3-4.2 mm, nearly as broad as long, wing margins entire or crenulate, face of perianth with or without 1 basal tubercle or spine.

Flowering year-round. Open sandy plains, edges of open oak woodlands; 0-200 m; Tex.; Mexico (Nuevo León, Tamaulipas).

Froelichia texana has been a relatively obscure taxon and has either been included within a broadly defined F. floridana or within F. interrupta (Linnaeus) Moquin-Tandon, a wide-ranging and morphologically variable species extending from northern Mexico to Peru. Similarities in overall growth form and the lack of divisions on the lateral wings of the mature perianth led to the long inclusion of this species within F. interrupta, although more detailed analysis points to a closer phylogenetic relationship between F. texana and F. floridana.

Froelichia interrupta has been reported to occur within the range of the flora; however, most of those records are, in fact, F. texana or misidentified F. arizonica. While I have seen no records definitively placing F. interrupta in the flora, I suspect it could occur as I have observed F. interrupta growing at higher elevations in northern Sonora. A suspected specimen of F. interrupta would key to F. texana, but differ by having a 3-ranked inflorescence and the fruiting perianth would always lack a basal tubercle or spine.