Hydrangea weberbaueri

Description. Root-climbing liana of up to 20 m high, functionally dioecious; free-growing branches quadrangular, slightly fissured; leaves decussate, petiole flattened adaxially, sulcate in young leaves (Fig. 15 B), terete abaxially, color dark brown to black, glabrous, leaving a semicircular to triangular scar on the branch when leaves fall, 1.0 - 2.6 cm long; lamina (ob) ovate to lanceolate, 13 - 21 cm long, 6 - 12 cm broad, base cuneate, sometimes asymmetric, apex rounded to acuminate, leaf margin slightly glandular-dentate, venation brochidodromous, veins 6 - 10 pairs, adaxial leaf side with midvein protruding, primary veins lightly marked, secondary veins barely visible, moderately pubescent with white, stellate hairs, caducous, abaxially with protruding midvein and primary veins, secondary veins marked, opaque olive green, secondary veins in between the primary veins parallel to these and forming a distinctive regular pattern with veins arching towards the apex (Fig. 15 A), sometimes, primary and secondary veins starting from nearly the same position on the midvein, densely pubescent with stellate reddish hairs, especially on the veins, caducous, sometimes nearly glabrous, acarodomatia numerous, not very conspicuous as they are hidden under the pubescence, in axils of midvein and primary veins, sometimes forming a small membrane partially covering the cavity; inflorescence axis pubescent with simple white hairs to glabrous (Fig. 15 C), 9 - 47 cm long, with 3 - 5 decussate leaf pairs below the inflorescence, persistent, petiole 0.5 - 1 cm long, lamina 2 - 11.5 cm long, 1.1 - 7.5 cm broad, adaxially glabrous, abaxially pubescent with small stellate hairs, apex of the inflorescence axis woody, cylindrical, elongated bract scars visible, thickening at the top, 6 - 10 mm broad, 4 - 7 mm high in functionally female plants, 5 - 7 mm broad, 4 mm high in functionally male plants, inflorescence bracts cucullate, cream-colored, coriaceous, margin membranous and glabrous to densely pubescent with yellowish stellate hairs, veins darker, parallel, bracts increasing in size, lowermost bract 2.5 - 3 cm large, 2.4 - 2.5 cm broad, inflorescences lateral, decussate, 1 - 3 pairs of inflorescences per flowering branch (Fig. 16 A), sometimes only one inflorescence developing, flowering branch continues growing vegetatively with the same vigor and periodicity above the inflorescences as below these, inflorescence axes with basal lignified parts of inflorescences of previous years visible in well-collected specimens, allowing to observe growth and flower periodicity, these rests 53 cm apart (in between the main branch ramified and those branches also carried inflorescences that flowered at the same time as the last inflorescences, Samain et al. 2013 - 130), medulla central in the branch, disappearing in older branches, leaving a hole only, inflorescence umbellate, buds up to 4.1 cm broad and 3.6 cm high before opening, in flowering stage 8 - 22.5 cm diameter, 3.5 - 14 cm high, with 6 - 10 main axes in functionally male plants, 7 - 14 main axes in functionally female plants, partial inflorescences cymes, secondary and tertiary inflorescence axes with reddish stellate hairs, pubescence gradually increasing towards flower insertion; enlarged marginal flowers sometimes present (Fig. 16 A-C), terminally placed in a cyme, sepals with marked veins, (2 -) 4, separate at the base, veins marked, palmate, reticulate, pistils 2, reduced, central part of the flower generally amorph, further characters not observed in detail, 1.5 - 3.7 cm diameter, pedicel 1 - 2.5 cm long; flower pedicel of reduced flowers 3 - 7 mm long in functionally male flowers, 3 mm long in functionally female flowers, receptacle triangular in functionally male flowers, rectangular in functionally female flowers, ovary inferior, calyx lobes 4, triangular, 0.2 mm long, petals 3 - 4, purple, valvate, cucullate, papyraceous, 2.2 - 2.5 mm long, 1.2 - 1.3 mm broad; functionally male flowers (Fig. 16 D): hypanthium 1.1 - 1.8 mm diameter, stamens 8, well-developed, filaments 3 mm long, anthers 0.8 - 1.0 mm long, 0.6 mm broad, pistils 2, reduced, 0.5 mm long, stigmas not penicellate; functionally female flowers (Fig. 16 E): hypanthium 1.0 - 1.8 mm diameter, stamens 8, reduced, filaments 0.1 - 0.4 mm long, anthers 0.1 mm long, 0.3 - 0.4 mm broad, pistils 2, 0.7 mm long, enlarging to 2 - 3 mm during fruit maturation, stigmas apically clavate and shortly penicellate; fruit a rectangular capsule, apically with a conspicuous border, ribs 4 - 6, pale reddish brown, 1.5 mm high, 2.5 mm broad above, 1.5 mm diameter, opening between the two pistils to release seeds, seeds not seen.