Hypericum tenuifolium (Nomenclature)
Shrub 0.1-0.5 m tall, decumbent, with branches interweaving at the base but not rooting, forming low mats, or sometimes more erect in dense vegetation. Stems reddish, 6-lined when young, eventually 4- lined, then terete; cortex exfoliating in strips or flakes; bark smooth, thin. Leaves sessile, 4-1 1 x 0.4-0.8(-1?) mm, with those in axillary clusters equal or shorter, linear-subulate, dull green above, with margin revolute, completely concealing all but midrib beneath, chartaceous, deciduous at articulation below prominent midrib base (cf. 11. brachyphyllum), apex rounded with prominent hydathode, base parallel or slightly expanded; midrib unbranched; glands dense, in 2 rows, visible beneath only. Inflorescence 1-7-flowered, without accessory flowers, with l(3)-flowered dichasia from up to 4 nodes below, rarely with one pair of flowering branches, the whole narrowly cylindric; pedicels absent or very short; bracts foliar. Flowers 10-14 mm in diam.; buds narrowly cylindric-ellipsoid. Sepals 5, (2-)2.5 4 x 0.4-0.5 mm, unequal, linear-subulate, acute to rounded, 1-veined. Petals 5, bright? yellow, spreading, 5-10 x 2-5 mm long, oblanceolate-oblong to obovate, with apiculus lateral, acute. Stamens c. 50-90, longest 4.5-8 mm, c. 0.85-0.9 x petals. Ovary 3-merous, 2-3 x 0.5-0.8 mm, very narrowly cylindric, acute; placentation parietal?; styles 3, 2-3 mm long, 0.9-1.2 x ovary, usually separating in fruit. Capsule (4-)5. 7-9.5 x 1 .5-2 mm, narrowly (sub)cylindric, exceeding sepals, thinly coriaceous. Seeds blackish, c. 0.5 mm long; testa coarsely reticulate (alveoli square to hexagonal).
2n = 18 (n = 9) (Adams in Robson & Adams, 1968).
Dry sandy woods, dunes and dune hollows; lowland and coastal.
South-eastern U.S.A. from North Carolina to central Florida and southern Alabama; four distinct populations: 1) south-eastern N. Carolina and adjacent S. Carolina; 2) extreme south-eastern S. Carolina and adjacent eastern Georgia; 3) central peninsular Florida; 4) coastal Florida 'panhandle' and adjacent Alabama.
H. tenuifolium, like H. lloydii, is closely related to (probably derived from) H. galioides, with which it shares all but the peninsular Florida part of its area. It is quite distinct from H. galioides, however, in habit, leaf size, inflorescence and habitat. Its distribution does not overlap the piedmont area of H. lloydii, which is also decumbent in form but has rooting stems and shorter leaves and (usually) sepals. For a comparison between H. tenuifolium and H. brachyphyllum, see p. xxx. Adams (1962) was aware that H. tenuifolium Pursh might be the earliest name for this species. Having been unable to find an authentic specimen, however, he published a new name, H. reductum. This was no doubt intended to maintain Svenson's (1940) epithet, although, because Svenson cited H. aspalathoides Willd. in synonymy, Adams could not treat his name as a stat. et comb. nov. In Kew (K), however, there is an Enslen specimen from Herb. Pursh. which I consider to be an authentic specimen of H. tenuifolium, and so the Philadelphia (PH) specimen cited by Adams can also be considered as authentic. Both these specimens belong to Adams's H. reductum, a name which must unfortunately therefore pass into synonymy under H. tenuifolium Pursh.