Hypericum watanabei (Nomenclature)
Perennial herb 0.23–0.33 m tall, erect to ascending from woody branching? base, with stems usually solitary, sometimes branched in middle. Stems narrowly 2-lined, usually soon terete, eglandular; internodes 20–25 mm, longer than leaves. Leaves sessile; lamina 25–40 × 7–18 mm, ovate- or oblong-lanceolate to elliptic, paler beneath, chartaceous; apex rounded to subacute, margin plane, base shallowly cordate-amplexicaul; venation: 3 pairs of main laterals from base and lower quarter to third of midrib; tertiary venation dense, partially visible above; laminar glands black and occasionally pale, punctiform, sparse; intramarginal glands black, dense. Inflorescencec. 16–20-flowered, from 2–3 nodes, rather dense, sometimes with branches from one node below, narrowly cylindric; pedicels 2–3 mm long; bracts reduced-foliar, bracteoles narrowly elliptic. Flowers c. 15–20 mm in diam., stellate; buds ellipsoid, rounded. Sepals 5, unequal, 3.3–3.6 × 1–1.5 mm, ovate or ovate-deltoid to oblong-lanceolate, subacute, entire; veins 3–5, occasionally branched and anastomosing; laminar glands pale, linear to striiform, proximal and black, striiform to punctiform, distal; marginal glands black, few, distal or irregular. Petals 5, bright yellow, not tinged red, 11–12 × 4 mm, 3–3.5 × sepals, narrowly elliptic, subacute, entire; laminar glands pale, linear; marginal glands black, 1–3, distal and/or apical. Stamens c. 30, ‘3’-fascicled, longest 9–10 mm, 0.8–0.9 × petals; anther gland black. Ovary 2.5–3 × 2 mm, ellipsoid; styles 3, free, basally incurved, 3–5 mm, c. 1.2–1.6 × ovary; stigmas narrow. Capsule and seeds not seen.
Japan (western Hokkaidō-Ishikari).
Although described as a variety of H. tatewakii (treated here as a subspecies of 15. H. nakaii), this taxon is in the affinity of H. yamamotoi, its nearest relative being 22. H. kimurae, with which it shares the black laminar sepal glands. Indeed, it seems to be intermediate between that taxon and 20. H. kawaranum, differing from both inter alia by the ovate to ovate-deltoid subacute sepals.