Shrub c. 1 m tall, with stems erect or arching, without or with a few short lateral branches. Stems 4-lined and ancipitous when young, soon unlined, eventually terete; internodes 25-70 mm long, mostly exceeding the leaves; bark reddish-brown. Leaves all sessile or the lower (or rarely all but uppermost) with flat petiole to 1-5 mm long; lamina (30-)37-75 x (10-)15-44 mm, oblong-lanceolate or oblong-ovate to broadly ovate, acute to rounded-apiculate, margin plane, not or scarcely incrassate, base rounded to subcordate, the upper amplexicaul, paler and ± glaucous beneath, coriaceous; venation: 3 pairs main laterals, with midrib branched distally, without visible tertiary reticulum; laminar glands long streaks and dots; ventral glands dense. Inflorescence (1) 3-13-flowered, from 1-2 nodes, subcorymbiform, with short or very short terminal internode, without branches below; pedicels 6-12 mm long; bracts on main stem broadly ovate, usually forming a pseudo-whorl, others reduced, broadly ovate to lanceolate, deciduous. Flowers 40-66 mm in diam., stellate to subcyath- iform; buds broadly ovoid, obtuse. Sepals (7-)10-15 x 4-9 mm, free, imbricate, subequal to unequal, erect in bud, ± spreading in fruit, ± broadly oblong to broadly elliptic or ovate, subapiculate or obtuse to rounded, with margin entire or slightly eroded towards apex; midrib distinct in outer sepals, obscure except near apex in inner ones, veins not prominent; laminar glands numerous, linear to punctiform. Petals pale to bright golden yellow, not tinged red, spreading or slightly incurved, 20-36 x 14-26 mm, c. 2.5-3 x sepals, obovate, with apiculus subterminal, rounded or almost absent; margin entire or very minute denticulate, eglandular. Stamen fascicles each with 60-70 stamens, longest 10-20 mm long, c. 0.5 x petals; anthers golden yellow. Ovary 5-6 x 4-5 mm, broadly ovoid; styles 6-8 mm long, c. 1.2 x ovary, erect to gradually divergent, outcurved towards apex; stigmas capitate. Capsule 10-12 x 9-10 mm, broadly ovoid. Seeds dark reddish-brown, c. 1.5 mm, long, cylindric, not or scarcely carinate, shallowly linear-reticulate.
2n = c. 54.
Collected at 1200-1890 m.
China (southern Yunnan).
H. augustinii, a local species from the extreme south of Yunnan, is related to H. pachyphyllum (from eastern Burma). It is a stout plant with large, coriaceous leaves and large flowers, characters which may be a result of polyploidy. It has not proved possible yet to obtain a consistent chromosome number. The numbers so far counted, which range from 48 to 55, suggest that H. augustinii may be a hexaploid on the base x = 9 (i.e. 2n = 54). In Europe, the species flowers too late in the season to allow fruits to develop.