Ziziphus horsfieldii Miq.

Cahen, D., Rickenback, J. & Utteridge, T.M.A. A revision of Ziziphus (Rhamnaceae) in Borneo. Kew Bull 76, 767–804 (2021). DOI: https://doi.org/10.1007/s12225-021-09970-3

Type

Indonesia, Java, 1802 – 1818, Horsfield s.n. (lectotype, selected here: K [K000723025]).

Morphology General Habit

Woody climber to at least 30 m long; girth to at least 10 cm in diam., spiny

Morphology Branches

Branchlets terete, with longitudinal striations and conspicuous, raised lenticels, hairs sparse, c. 0.5 mm long mixed with shorter hairs ˂ 0.1 mm long, mostly appressed-antrorse, reddish to whitish

Morphology Leaves Stipules

Stipules modified into spines, single, recurved, c. 2.5 mm long, subglabrous

Morphology Leaves

Leaves weakly discolorous, drying greenish-brown, blade asymmetric, (lanceolate –) narrow ovate (– ovate), 3.5 – 10.0 × 1.2 – 4.5 cm, chartaceous to subcoriaceous, apex attenuate to acuminate, base cuneate to subcordate, usually clearly oblique, margins finely denticulate, c. 100 serrations on either side, each serration topped by a protruding callosity that dries darker than the lamina, c. 0.1 mm long; primary veins 3, impressed adaxially, raised abaxially, hairs sparse along primary veins on either side of lamina, often more densely adaxially, hairs c. 0.2 mm long; strong marginal veins coming off the outside of the two outer main veins c. 6 on either side, rarely < 5, ascending and gradually diminishing, not forming conspicuous loops near margin¸ no clear intramarginal vein running along the leaf margin present, angle of divergence with outer main veins c. 45°; transverse veins between the main veins weak but discernible, especially adaxially, coming off midrib at c. 90°, barely raised (not readily felt by touch), spaced by c. 1 mm from each other, more often slightly zigzagging than straight; higher order reticulations barely discernible; lamina subglabrous; domatia present in the axils at the base of the 3 main veins and at the junction between the marginal veins and the outer main veins, pocket-like and often with tufts of hairs, swelling often visible adaxially just above junction between 3 main veins; petiole slightly dorsiventrally flattened, c. 7 mm long, hairs dense, indumentum extending to widened base of main veins adaxially

Morphology Reproductive morphology Inflorescences

Inflorescence of axillary pedunculate cymes, < ½ as long as subtending leaves, c. 12 flowers in each cyme, cymes loose dichasia with usually peduncle and first 2 branches clearly elongate and next 4 branches short but distinct; peduncles dorsiventrally flattened (5 –) 10 (– 15) mm long, hairs abundant, mostly < 0.1 mm long; pedicels c. 2 mm long, straight to slightly curved; bracteoles entire, narrowly triangular, c. 1 mm long, hairy

Morphology Reproductive morphology Flowers

Flower faintly scented; hypanthium densely hairy on the outer surface, hairs ˂ 0.1 mm long, appressed-antrorse, greyish; sepals triangular, c. 1.2 mm long, pale greenish when fresh, glabrous and keeled adaxially; petals clawed, c. 1 mm long, obcordate, white; stamen filaments flat, subulate, c. 0.7 mm long, anthers c. 0.3 mm long, enclosed by petals; nectary disk yellow, pentagonal, 10-pitted, glabrous, annulus surrounding ovary barely raised; style arms 2, free for c. 1 mm, glabrous; ovary partially immersed, hairs dense

Morphology Reproductive morphology Fruits

Fruit a drupe, ripening yellowish-green, (0.9 –) 1.1 (– 1.5) × (0.7 –) 1.1 (– 1.5) cm, obovoid [wider towards apex], indumentum dense, hairs drying reddish, < 0.1 mm long; fruiting pedicels c. 5 ×1 mm; hypanthium remains annular at base of fruit.

Distribution

Brunei, Indonesia (Java, Kalimantan, Sumatra), Malaysia (Malay Peninsula, Sabah, Sarawak), Philippines (Mindoro, Palawan), Singapore.

Ecology

Borneo lowland rain forests; alt. 30 – 520 m.

Conservation

Least Concern (LC). Ziziphus horsfieldii is widely distributed in western Malesia and extends to the Philippines. It does not appear to be threatened. In Borneo, it could be declining and severely fragmented given recent widespread destruction of rainforests but was collected in the following protected areas in Sabah: Bidu-Bidu Protection Forest Reserve (IUCN Category Ia), Klias Protection Forest Reserve (IUCN Category not reported) and SG. Kinabatangan Valley Bird Sanctuary (IUCN Category not reported).

Phenology

Collected in flower in April, June, Oct. and Dec.; collected in fruit in March, June – Oct. and Dec.

Vernacular

Kanggomsopuan (Sandakan, fide Bousi et al. SAN 124340); Kuku menaul (Iban, fide Luang S.23451); UnakMenaul (Iban, fide Wong WKM 1281).