Hypericum assamicum (Nomenclature)
Perennial or sometimes suffruticose herb 0.2-0.3(-0.4) m tall, erect, with stems often many from stout woody base. Stems terete; internodes 2-6.5 mm, shorter than to exceeding leaves. Leaves in perfoliate pairs; lamina 15-50 ´ 6-15 mm, oblong to oblanceolate, often suddenly somewhat narrowed below middle, glaucous beneath, plane, thinly chartaceous; apex obtuse to rounded, margin entire or rarely 'glandular-crenulate', base broadly cuneate to rounded, common base narrowed; venation: 2-3(4?) pairs of main laterals usually from lower third to half of midrib, branching and uniting near margin, with tertiary reticulation not prominent; laminar glands black, punctiform, dense; intramarginal glands black, dense. Inflorescence c. 12-18-flowered from 2 nodes, corymbiform, with flowering branches from up to 2 nodes below, the whole then corymbiform to subpyramidal; pedicels 1-10 mm; uppermost bracts and bracteoles linear-subulate, other bracts foliar. Flowers c. 12 mm in diam., apparently stellate; buds ovoid-ellipsoid. Sepals 5, 5-8.5 ´ 1-2 mm, free, unequal, erect in bud and fruit, 3 larger oblanceolate-spathulate, 7-8.5 ´ 2 mm, 2 smaller oblanceolate to narrowly oblong, 5-5.5 ´ 1 mm, obtuse to acute, entire or with subapical marginal glands prominent; veins 3, midrib branched; laminar glands rather few, pale and sometimes black, punctiform; intramarginal to marginal glands irregularly spaced, black. Petals 5, 'yellowish', not tinged red in bud, c. 5 ´ 1.7 mm, oblanceolate-spathulate, subobtuse or obtuse, margin entire? or with marginal glands ± prominent; laminar glands pale, striiform to punctiform, and a few black, punctiform; intramarginal to marginal glands black, immersed to sessile. Stamens c. 15, longest 4-5 mm, equalling petals or almost so; anther gland black. Ovary 1-locular with intrusive placentae, c. 2.7 ´ 2 mm, ovoid,; styles 3, c. 1 mm, c. 0.35 ´ ovary, free, erect; stigmas capitellate. Capsule 5-6 ´ c. 4 mm, cylindric-subglobose, about equalling sepals, valves with scattered punctiform amber vesicular glands. Seeds reddish brown, c. 0.8 mm long, cylindric, not carinate or appendiculate; testa finely ribbed-scalariform.
'Jungles'; lowland.
India (Meghalaya).
H. assamicum is clearly closely related to H. sampsonii, the question being whether or not it is distinct. With one possible exception all its characters are derivative relative to those of H. sampsonii, and so it can be seen as a development from the south-eastward distributional 'arm' of that species through Yunnan to south-eastern Myanmar on the Salween River. This 'outstation' of H. sampsonii is c. 850 km from the only locality of H. assamicum, in the Bramaputra plains of Assam.
H. assamicum can be distinguished from H. sampsonii by the narrowed (not expanded) common leaf base, the longer stamens, the unilocular ovary with relatively and absolutely shorter styles and possibly the more clumped habit with woody base. Of these characters, only the narrowed common leaf base and longer stamens are possibly not derivative. Relative to H. sampsonii, it is therefore probably a neo-endemic.