7. Acanthoscyphus Small, Bull. Torrey Bot. Club. 25: 53. 1898.
Flowery puncturebract [Greek acantha, thorn, and scyphos, cup, alluding to awn on involucre]
James L. Reveal
Oxytheca Nuttall sect. Acanthoscyphus (Small) Ertter
Herbs, annual; taproot slender. Stems arising directly from the root, erect to somewhat spreading, solid, not fistulose or disarticulating into ringlike segments, glabrous, partially glandular. Leaves usually persistent through anthesis, basal, rosulate; petiole indistinct; blade broadly obovate or spatulate to oblong or oblanceolate, margins ciliate-denticulate. Inflorescences terminal, cymose; branches dichotomous, not brittle or disarticulating into segments, round, glabrous except for glandular nodes and proximal 2 of internode; bracts 2-3, connate basally, scalelike, triangular to lanceolate or subulate, awned at proximal nodes, glabrous or sparsely glandular. Peduncles erect to deflexed. Involucres 1 per node, not ribbed, tubular, turbinate; teeth 4(-5) or 7-30(-36), 1/ 2 to completely connate, awn-tipped, glandular distally adaxially. Flowers 3-10(-20) per involucre at any single time during full anthesis; perianth white to rose, occasionally greenish white to cream, broadly campanulate when open, narrowly urceolate when closed, hirsute to strigose and sparsely glandular abaxially; tepals 6, connate 4- 3 their length, monomorphic, entire or rarely irregularly divided apically; stamens 9; filaments basally adnate, glabrous or sparsely pubescent basally; anthers red to maroon, oblong to oval. Achenes usually included, dark brown to deep maroon, not winged, globose-lenticular, glabrous. Seeds: embryo curved. x = 20.
Species 1: s California.
Acanthoscyphus is allied to Eriogonum subg. Ganysma, specifically to E. parishii, E. apiculatum, and their close relatives. It is distinguished from Eriogonum by its awned involucres.
SELECTED REFERENCE
Ertter, B. 1980. A revision of the genus Oxytheca (Polygonaceae). Brittonia 32: 70-102.
