Herbs; latex white, dilute. Stems usually solitary, erect, unbranched, unarmed, densely hirsute with long, eglandular and minutely glandular trichomes. Leaves persistent, opposite, petiolate, surfaces densely hirsute with long, eglandular and minutely glandular trichomes; stipular colleters absent; laminar colleters present. Inflorescences extra-axillary, cymose, umbelliform, solitary at nodes, sessile or pedunculate. Flowers: calycine colleters apparently absent; corolla cream with longitudinal green lines, urceolate [campanulate], lobes erect to spreading, aestivation contort-dextrorse; corolline corona absent; androecium and gynoecium united into a gynostegium adnate to corolla tube; gynostegial corona of 5 laminar segments opposite stamens, distinct, fused to gynostegium at base of anthers; anthers adnate to style, apex with laminar appendages covering margins of style apex, locules 2; pollen in each theca massed into a rigid, horizontally oriented pollinium, pollinia strongly curved, bearing sterile, navicular portion adjacent to translator, pollinia of adjacent anthers joined by translators to common corpulsculum, together forming a pollinarium. Fruits follicles, typically solitary, sharply deflexed, fusiform, surface smooth, densely villous or hirsute, tardily glabrate. Seeds winged, not beaked, ovate, flattened, comose, not arillate.

Distribution

Arizona, Mexico, Central America (Guatemala).

Discussion

Species 5–9 (1 in the flora).

Pherotrichis was formerly included in a broadly circumscribed, paraphyletic Matelea and is distinctive in subtribe Gonolobinae (which also includes Gonolobus and Matelea) by the erect, non-twining habit and the densely barbate corolla lobes. The removal of Pherotrichis from Matelea is but one of several generic realignments necessary to circumscribe a monophyletic Matelea. Species of Pherotrichis are very commonly mistaken for Asclepias but are readily dis­tinguished by the urceloate (or campanulate in extra-regional species) corollas with villous lobes concealing the minute corona and by the sharply deflexed follicles.

Selected References

None.

Lower Taxa

Pherotrichis schaffneri