Hypericum choisyanum (Nomenclature)
Shrub (0.3-)1-2 m tall, bushy, with branches erect to ascending. Stems red to orange, 4-lined and ancipitous when young, eventually terete; internodes 15-55 mm long, usually shorter than leaves; bark grey-brown. Leaves petiolate, with petiole 2-4 mm long; lamina 25-88 x 10-42 mm, triangular-lanceolate or rarely triangular-ovate to ovate, acute or acuminate to obtuse or rarely rounded, margin plane, base broadly cuneate to rounded or subcordate, paler beneath, not glaucous, chartaceous; venation: 3-5 pairs main laterals, branched, the lower pairs sometimes free, the midrib branches impressed, with tertiary reticulum almost invisible to marked and rather dense; laminar glands streaks and dots; ventral glands absent. Inflorescence 1-7-flowered, from terminal node, subcorymbiform; pedicels 3.5-11 mm long; bracts foliar to narrowly elliptic, persistent. Flowers 40-70 mm in diam., shallowly to deeply cyathiform; buds ovoid, sharply acute to obtuse. Sepals 7-18 (or longer if markedly foliaceous) x 2-10 mm, free, imbricate or open, unequal, spreading to recurved in bud and fruit, narrowly to very broadly elliptic, acute to apiculate or more rarely obtuse, with margin entire; midrib clearly visible, veins not usually prominent; laminar glands linear, interrupted towards apex, numerous. Petals deep golden yellow, sometimes tinged red dorsally, slightly to markedly incurved, 16-30 x 15-22 mm, 1.7-2.2 x sepals, broadly obovate to obovate-circular, with apiculus subterminal, rounded, margin entire, eglandular. Stamen fascicles each with 60-80 stamens, longest 6-10 mm long, 0.35-0.4 x petals; anthers golden yellow. Ovary (5)6-8(9) x 3.5-5.5 mm, ± broadly ovoid; styles 3-5 mm long, 0.5-0.7 x ovary, free, outcurved near apex; stigmas narrowly capitate. Capsule (9-)14-19 x 8-12 mm, ovoid-conic to subglobose. Seeds dark brown, 0.7-1 mm long, cylindric to cylindric-ellipsoid, carinate or shallowly winged, shallowly linear-reticulate to linear-foveolate.
Dry to moist, open to half-shaded situations (grassy or rocky slopes or cliffs, in thickets or in Rhododendron forest); 1600-4800 (Tibet), mainly 2400-4200 m.
China (Yunnan, S. Xizang), Burma (north), Bhutan, Sikkim, Nepal, India (W. Bengal, Kumaun to Kashmir), Pakistan (Hazara).
H. choisyanum has sometimes been confused with the Indonesian H. leschenaultii, on account of the narrow sepals that occur in both species; but it differs from that species particularly in the ovary and capsule, which are ovoid-conic to subglobose (not narrowly conic), but also in its relatively longer stamens and styles, broader ovary and capsule, longer petiole and frequently more densely reticulate leaf venation. H. choisyanum seems to be a relative of H. maclarenii, whereas H. leschenaultii is related to H. subsessile in a somewhat parallel way. H. choisyanum can also be very similar to H. hookerianum, which grows in a lower but overlapping zone of the central and eastern Himalaya; but the erect, rounded, never foliaceous sepals, relatively shorter stamens and styles, and bluish leaves without reticulate venation of the latter usually serves to distinguish it. In Nepal, H. choisyanum takes on a rather distinct facies in which the typical form (leaves with venation ± obscurely reticulate, flowers solitary or rarely 2-3, sepals ovate to lanceolate) is replaced by one in which the leaves always have markedly reticulate venation and the flowers are usually in cymes of 3-7 with narrowly lanceolate to narrowly elliptic sepals. Although this form is easily recognisable, it is connected by too many intermediates with the typical one to allow it taxonomic recognition. The Chinese and Burmese plants, from isolated localities divorced from the main Himalayan range of the species, are superficially rather similar to H. bellum; and the one from furthest east (Li 3458) is unusual in having almost elliptic leaves with a rounded apex.
The alteration of the spelling of the specific epithet of this species from choisianum to choisyanum results from the operation of the IBCN Art.60.7, which bans the latinisation of the name Choisy to Choisius.
A collection from Bhutan (Rushforth 34-1657)) that grew for some years in our Limpsfield garden was a dwarf form of (or species allied to) H. choisyanum. Unfortunately it died before I was able to make a specimen from it. It differed from H. choisyanum as follows (typical species characters in square brackets):
Shrub c. O.75 [1-2] m tall, with branches erect-arching to widely spreading [erect to ascending]. Leaves with petiole 1-2 [2-4] mm long; lamina lanceolate [triangular-lanceolate to ovate], apex rounded [acuminate to obtuse]; venation 2(-3) [3-5] pairs main laterals. Inflorescence 1 [1-7]-flowered. Flowers 35-40 [40-70] mm in diam.Petals 12-16 [15-22] mm wide. Stamen fascicles each with c. 40 [60-80] stamens; anthers dull orange [golden yellow]. Ovary with styles 2.5-3 [3-5] mm long, c. 0.1 [0.35-0.7] x ovary. Capsule 12-15 [14-19] x 5-8 [8-12] mm, ovoid-cylindric to cylindric-ellipsoid.
It is possible that others will have been more successful in growing Rushforth 34-1657 than we were, in which case one would be able to name and typify this taxon without having to re-collect it from the wild.