Shrubs, subshrubs, or herbs, perennial or annual, synoecious, dioecious, gynodioecious, or gynomonoecious; taproots woody. Stems erect, decumbent, or prostrate, glabrous or scabrous. Branches adnate to stems, appearing to arise internodally. Leaves deciduous or, rarely, with leaves persisting more than 1 year, sometimes fugacious, cauline, alternate; ocrea usually persistent, sometimes disintegrating with age and deciduous distally, chartaceous or coriaceous; petiole apparently absent, articulate basally; blade filiform to broadly obovate, margins entire. Inflorescences terminal, racemelike, pedunculate. Pedicels present. Flowers bisexual, or some or all functionally unisexual, 1 per ocreate fascicle, base stipelike; perianth nonaccrescent, white, pink, red, greenish, or yellowish, campanulate, glabrous; tepals 5, distinct, petaloid, dimorphic, in 2 whorls with 2 outer and 3 inner or 2 outer and 2 inner plus 1 transitional; stamens 8, in 2 series with 5 outer and 3 inner; filaments distinct, free, dilated proximally, dimorphic, inner 3 dilated more abruptly than outer 5, with toothed or horned shoulders, or monomorphic (in P. fimbriata and P. robusta), glabrous (pubescent basally in P. basiramia); anthers white, yellow, orange, pink, or dark red, elliptic to ovate or round; styles (2-)3, erect, distinct; stigmas (2-)3, capitate. Achenes included or exserted, yellow-brown, brown, or reddish brown, wingless or narrowly winged, (2-)3(-4)-gonous, glabrous. Seeds: embryo straight or slightly curved. x = 11.
Fls perfect or unisexual; tep 5, petaloid, persistent and ±accrescent; stamens 8 (5 + 3), the filaments sometimes dimorphic; ovary trigonous; styles 3, distinct; stigmas capitate; fr a smooth, sharply trigonous achene, subtended and loosely invested by the perianth; embryo slender, straight or nearly so; taprooted herbs or subshrubs of somewhat heathlike aspect, commonly freely branched, with small lvs and white to red fls in compound racemes, each fl solitary in the axil of a sheathing bract; lvs jointed to the summit of the ocrea; pedicels articulated just above the base. 10, N. Amer.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.