Hypericum yamamotoi (Nomenclature)
Perennial herb c. 0.5 m long, suberect to ascending or procumbent from woody base, with stems usually solitary, unbranched below inflorescence. Stems narrowly 2-lined at first, sometimes soon terete, eglandular; internodes 15–55 mm, equalling or exceeding leaves. Leaves sessile; lamina 35–50 × 15–20 mm, narrowly oblong to lanceolate, paler beneath, chartaceous; apex rounded to subapiculate-obtuse, margin plane, base rounded to subcordate-amplexicaul; venation: 3–4 pairs of main laterals from lower fifth to 2/5 of midrib and sometimes base; tertiary reticulation dense, visible on both sides; laminar glands black, scattered and sometimes pale, few, especially in upper leaves, all punctiform; intramarginal glands black, dense. Inflorescence 5–15-flowered, from 3 nodes, lax, with branches from 2 nodes below, the whole broadly pyramidal; pedicels 2–3.5 mm, slender; bracts reduced-foliar, bracteoles linear-lanceolate. Flowers c. 20 mm in diam., stellate; buds ellipsoid, rounded to subobtuse. Sepals 5, unequal, 3.5–5.5 × 1–1.5 mm, linear-oblong to linear-lanceolate, subacute to acute, entire; venation: 5, outer sometimes branching and anastomosing; laminar glands pale, striiform to punctiform; marginal glands black, few (1–4) or absent. Petals 5, bright? yellow, not tinged red, 10–12 × c. 2.8 mm, 2–3 × sepals, narrowly oblanceolate, rounded, entire; laminar glands pale, linear; marginal glands absent. Stamens c. 35, ‘3’-fascicled, longest 10–11 mm, c. 0.9 × petals; anther gland black. Ovary 3.5–4 × 1.5 mm, ellipsoid; styles 3, free, widely incurving, 6 mm, c. 1.5 × ovary; stigmas narrow. Capsule and seeds not seen.
Japan (Hokkaidō).
The type specimen of H. yamamotoi differs from material of nearly all other subordinate taxa subsequently appended to it in its ascending to procumbent habit, large narrow leaves, narrow sepals and petals with only pale laminar glands. 24. H. pseudoerectum tends toward that species in its narrow (but smaller) leaves and narrowish sepals with only pale laminar glands, but differs, for example, in the denser inflorescence and shorter styles; whereas 22. H. kimurae is much nearer H. yamamotoi, being intermediate between it and 21. H. watanabei.