Hypericum setosum
Perennial or annual herb 0.2-0.7(-0.8) m tall, erect, unbranched below inflorescence or occasionally with 1-2 flowering branches from upper stem nodes. Stems green, 4-lined, sparsely (?) gland-dotted, scabrous-tomentose to pilose; internodes 5-20 mm long, lower equalling leaves, upper longer than them. Leaves sessile, appressed to ascending, spreading when fading; lamina 4-15 x (1.5)2-7 mm, narrowly ovate or lanceolate to narrowly oblong-elliptic (or lower sometimes oblanceolate), margin recurved, concolorous, not glaucous, subcoriaceous, scabrous-tomentose to pilose; apex acute to obtuse, base rounded-subamplexicaul to parallel- sided, not decurrent, free; basal vein(s) l(-5), midrib without or with 1 pair of branches, tertiary reticulation not visible; laminar glands dense, slightly prominent beneath. Inflorescence up to c. 30-flowered (terminal), monochasial after 1st or 2nd grade, sometimes with up to 15-flowered dichasial/monochasial or usually wholly monochasial branches from up to 5 lower nodes, occasionally with 1-2 pairs of subsidiary flowering branches below, the whole cylindric to subcorymbiform; pedicels 1.5-2 mm long; bracts 2 mm long, lanceolate, setulose-ciliate. Flowers c. 5-11 mm in diam., stellate. Sepals (2.5-)3-5 x 1.5-2.5 mm, subequal, ovate to ovate-lanceolate or obovate, acute; veins 5-7, unbranched, only midrib or all veins slightly prominent, but less so than glands; glands linear, distally punctiform; margin setulose-ciliate, lamina sparsely setulose to glabrous. Petals (deep ?) yellow, 4-7 x 4-7 mm, 1.5-2 x sepals, obovate; apiculus acute; glands linear, interrupted distally. Stamens (15) 20-40, almost free, longest 2.5-3 mm long, 0.65-0.75 x petals. Ovary c. 1.5 x 0.8 mm narrowly ovoid-ellipsoid; styles 3(4), 1.5-2 mm long, 1-1.3 x ovary, outcurving; stigmas broadly capitate. Capsule (3.5-)4-5 x 2-3 mm, ovoid to ellipsoid-subglobose, equalling or slightly exceeding sepals. Seeds 0.4-0.6 mm long, ecarinate; testa linear-reticulate.
2n = 12 (Webb, 1980).
Wet ditches, bogs, savannahs, and wet pinelands on sandy soil; lowland.
South-eastern U.S.A. (coastal plain from Virginia to northern Florida and west to Louisiana and E. Texas (fide Correll & Johnston, 1970)).
H. setosum is related to H. erythreae, being smaller, without basal branches, and setose or pilose on stem, leaves, and sepals. It is the only species in sects 29-30 with an indumentum. Its nearest relative in H. erythreae appears to be the population from Alexander Co., N. Carolina (growing on granite outcrops) that Webb (1980) regarded as somewhat aberrant. If H. setosum is indeed related to H. erythreae, then Webb's chromosome count (2n = 12) shows it to be haploid, or at least to have half as many chromosomes as its relative (2n = 24). How this halving has occurred is not at all clear; but I cannot agree with Webb that H. setosum has the most primitive chromosome number in Hypericum. 2n = 12 is clearly not a basic diploid number, otherwise the arborescent and shrubby species with 2n = 24 would have to be regarded as tetraploids and a sister group in some obscure way to H. setosum (and H. cumulicola q.v.).