Description

Description. Root-climbing liana of probably not more than 15 - 20 m high; functionally dioecious; free-growing branches slightly quadrangular, densely pubescent with reddish brown stellate hairs; leaves decussate, petiole sulcate adaxially, terete abaxially, color reddish brown, densely pubescent with caducous, reddish-brown, stellate hairs, 0.6 - 1.5 cm long, leaving a semicircular scar on the branch when leaves shed; lamina flat, ovate to lanceolate-elliptic, 6 - 12 cm long, 2.6 - 5.5 cm broad, base rounded to decurrent, sometimes asymmetric, apex acuminate, leaf margin glandular dentate, teeth generally small, larger in only a few leaves, venation brochidodromous, veins 5 - 7 pairs, adaxial leaf side with marked midvein, primary and secondary veins lightly marked, primary veins join to form submarginal vein, sparsely pubescent with appressed, white stellate hairs, in young leaves more dense and reddish hairs, abaxially with protruding veins, primary veins sometimes alternating protruding and marked in the same leaf, dark brown green, densely pubescent with appressed stellate reddish hairs near the midvein, rest of the lamina more sparsely pubescent, acarodomatia present, numerous, consisting of a simple cavity, but often not very conspicuous as they lay hidden under the midvein pubescence, in axils of midvein and primary veins; inflorescence axis densely pubescent with persistent reddish brown, stellate hairs, more dense towards the apex, 8 - 21 cm long, many-ribbed, with up to 3 opposite or decussate leaf pairs and up to 3 scars of possibly kataphyll pairs below the inflorescence, deciduous, petiole 5 - 15 mm long, lamina 6 - 12.5 cm long, 2.5 - 5.5 cm broad, kataphylls not seen, apex of the floral axis woody, basally quadrangular, apically triangular, elongated bract scars visible, 3 - 4 mm broad, 1.5 - 2 mm high in functionally female plants, 3.5 - 5 mm broad, 2 - 2.5 mm high in functionally male plants, inflorescence bracts cucullate densely pubescent, hairs reddish-brown, stellate, increasing in size, lowermost bract 1.5 cm large, 1.2 cm broad, other bracts not visible, inflorescences lateral (Fig. 1), decussate, 1 - 3 pairs of inflorescences per flowering branch, flowering branch only continues growing vegetatively rapidly during inflorescence development, with up to 6 leaf and kataphyll pairs above the inflorescences, inflorescence axes with basal lignified parts of inflorescences of previous years not seen, kataphylls at the base of the inflorescence present, orbicular, inflorescence umbellate, buds not seen, in flowering stage 4 - 12 cm diameter, 2.5 - 7 cm high, with 6 - 9 main axes in functionally male plants, 6 - 8 main axes in functionally female plants, partial inflorescences cymes, secondary and tertiary inflorescence axes densely pubescent with reddish, stellate hairs, pubescence gradually decreasing towards flower insertion; enlarged marginal flowers always present, terminally placed in a cyme, sepals 4, separate, with marked veins, pistils 2, fertile or reduced, some flowers with mature fruit, in these cases only 1 sepal visible, 1.5 - 2.3 cm diameter, pedicel 1 - 2 cm long, reddish-purple; flower pedicel of reduced flowers, 0.2 - 1.5 mm long in functionally male flowers, 0.5 - 2 (- 3) mm long in functionally female flowers, receptacle triangular in functionally male flowers, semiglobose in functionally female flowers, ovary inferior, calyx lobes 4, triangular in male flowers, nearly reduced to zero in female flowers, enlarging during fruit maturation, reduced, petals 4, bright red to purple, cucullate, 1.2 mm long; functionally male flowers: hypanthium 1 - 1.2 mm broad, 0.8 - 1 mm high, stamens 8, well-developed, pink, filaments 0.5 - 1.5 mm long, anthers 0.5 mm long, 0.2 mm broad, pistils 2, reduced, 0.2 mm long, stigmas not penicellate; functionally female flowers: hypanthium 1 mm diameter, 0.5 mm high, stamens 8, reduced, filaments and anthers together 0.2 mm long, pistils 2, 0.5 - 0.8 mm long, enlarging up to 2 mm during fruit maturation, stigmas slightly apically clavate and shortly penicellate; fruit a semiglobose capsule, apically with a thickened border, dark reddish brown, 0.8 - 1.2 mm high, 1.5 mm broad above, 1.5 mm diameter, opening between the two pistils to release seeds, seeds not seen.

Common Names

Taxonomic Hierarchy

Kingdom: Plantae

Phylum: Tracheophyta

Class: Magnoliopsida

Order: Cornales

Family: Hydrangeaceae

Genus: Hydrangea

Species: Hydrangea caucana Engl.