Hypericum yamamotoanum H.Koidz.

Perennial herb 0.35–0.4 m tall, erect to ascending from woody? base, with stems caespitose, unbranched below inflorescence or branching at upper nodes. Stems narrowly 4-lined at first, 2-lined below, eglandular; internodes 20–40 mm, shorter to longer than leaves. Leaves sessile; lamina 25–40 × 13–25 mm, oblong-ovate to (lower) broadly elliptic, paler beneath, chartaceous; apex rounded, margin plane, base rounded to shallowly cordate-amplexicaul; venation: 3–4 pairs of main laterals from lower quarter to third of midrib; tertiary reticulation dense, visible on both sides; laminar glands black, punctiform, sparse or absent; intramarginal glands black, dense. Inflorescence (3–)10–15-flowered, from 1–3 nodes, rather lax but individual triads dense, when from one node then with lower branches, the whole subcorymbiform; pedicels 1.5–4 mm, slender; bracts and bracteoles reduced-foliar, ovate. Flowers c. 16–21 mm in diam., stellate; buds ellipsoid, rounded. Sepals 5, very unequal, 4–7 × 1.3–2.5 mm, ovate to oblong or lanceolate, rounded to obtuse or subacute, entire; veins 5, branching and anastomosing; laminar glands black and/or pale, punctiform, rather few; marginal glands black or pale, spaced, regular or irregular. Petals 5, bright? yellow, not tinged red, 10–12 × 3 mm, 2–3 × sepals, oblong to oblong-spathulate, rounded, entire; laminar glands pale, proximal linear to striiform and sometimes black, distal striiform to punctiform; marginal glands black, very few (1–2) or absent. Stamens 40–60, ‘3’-fascicled, longest 7–9 mm, c. 0.6 × petals; anther gland black. Ovary 3–4 × 1.5–2 mm, ovoid-ellipsoid; styles 3, free, divaricate-incurving, 3.5–5(–7) mm, 1–1.5 × ovary; stigmas narrow. Capsule and seeds not seen.