Hypericum myrtifolium (Nomenclature)
Shrub (or subshrub?) 0.3-1 m tall, mostly 1-stemmed, erect from woody caudex, often unbranched below inflorescence, sometimes with branches in upper half, ascending. Stems glaucous green, 4-lined and ancipitous when young, soon 4-lined and rounded, becoming reddish brown and 2-lined to terete; cortex exfoliating in strips; bark greyish, becoming corky, thick. Leaves sessile, spreading, evergreen, (8-)13-40 x (5-)7-20 mm, oblong-ovate to triangular-lanceolate, margin recurved (especially when dry), paler and usually glaucous beneath, sometimes also glaucous above, coriaceous, eventually deciduous at or near semi-articulated base, apex rounded to obtuse or sometimes acute, base subcordate to cordate, amplexicaul; venation: 3-4 main laterals, with laxly reticulate secondaries, tertiaries not visible; laminar glands very dense. Inflorescence 7-c. 30-flowered, regularly dichasial, widely branched, sometimes with 1-3 accessory flowers at apical node, with solitary flowers or 3-7-flowered dichasia or flowering branches up to 3 nodes below, the whole hemispherical to subcorymbiform; pedicels to 3 mm long or absent; bracts foliar, reduced. Flowers (15-)20-25 mm in diam.; buds ovoid. Sepals 5, 5-8 x 2-4.5 mm, enlarging somewhat in fruit, imbricate, unequal to subequal, ovate to lanceolate, becoming foliaceous, acute, margin recurved; basal veins (3)5, branching and reticulating distally. Petals 5, bright yellow, becoming apically recurved, 8-15 x 4.5-6 mm, 1.5-2 x sepals, obovate to oblong-oblanceolate, with apiculus lateral, obtuse. Stamens c. 200, longest 5-9 mm, c. 0.6 x petals, deciduous. Ovary 3(4)-merous, 3-4 x 1.3-3 mm, narrowly pyramidal-ovoid, acute, placentation incompletely axile; styles 3(4), 4-5 mm, 1.2-1.3 x ovary, separating above in fruit. Capsule 5-6 x 3-4 mm, pyramidal-ovoid, 3(4)-lobed or 3(4)-gonous. Seeds blackish brown, c. 1 mm long, narrowly carinate; testa shallowly linear-reticulate.
2n = 18 (n = 9, Adams in Robson & Adams, 1968).
Moist pine flatwoods, grass/sedge bogs, margins of evanescent ponds and low roadside ditches, on sandy or peaty soil; lowland.
U.S.A. (coastal plain from South Carolina? or Georgia to south-eastern Mississippi, including most of peninsular Florida).
Small (1933) recorded H. myrtifolium from South Carolina, and there is a specimen in Herb. De Candolle (G-DC) labelled 'Carol, merid., Fraser'; but this species is not treated by Radford, Ahles & Bell (1968).
Adams (1962) included H. myrtifolium in subsect. Centrosperma, and the leaves do have a groove at the base of the midrib beneath. It does not extend along the rest of the lamina base, however, so that the leaves sometimes leave a small zone behind when they fall. In addition, the sepals are persistent after fruit dehiscence, but the stamens are deciduous with the petals and the placentation is incompletely axile. All these characters suggest that H. myrtifolium could be intermediate between subsections Centrosperma and Suturosperma, but the habit, leaf shape, larger sepals and numerous stamens indicate a direct relationship with 1. H.frondosum.