Ziziphus Mill.

M. Thulin. Flora of Somalia, Vol. 1–4 [updated 2008] https://plants.jstor.org/collection/FLOS

Distribution

Genus of some 85 species, widely distributed in tropical and warm temperate regions, mostly in dry areas.

Morphology General Habit

Shrubs or trees, usually armed with straight or hooked stipular spines; branches often zigzag

Morphology Leaves

Leaves alternate, crenate to serrate, usually 3–5-nerved from the base

Morphology Reproductive morphology Flowers

Flowers in axillary cymes or clusters, bisexual, 5-merous

Morphology Reproductive morphology Flowers Disc

Disk thickened around the ovary but free from it

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary 2(–4)-celled; style 2(–4)-lobed

Morphology Reproductive morphology Fruits

Fruit a globose drupe with a single 2(–4)-celled stone.

Rhamnaceae, Marshall C. Johnston (University of Texas Herbarium). Flora of Tropical East Africa. 1972

Morphology General Habit

Trees or shrubs (or scandent shrubs or almost lianes but not in East Africa), often armed by spinous stipules (or by branch-thorns but not in East Africa), the branchlets often zig-zag

Morphology Leaves

Leaves alternate or opposite, petiolate; blades often 3- or 5-nerved from the base and penninerved above, often ovate or elliptic, with serrulate margins (or entire margins but not in East Africa)

Morphology Leaves Stipules

Stipules present, often at some nodes transformed into short spines, some of which are recurved, the stipules small, subulate and quickly deciduous at those nodes where they are not so transformed

Morphology Reproductive morphology Flowers

Flowers 5-merous, bisexual, usually in axillary cymes or thyrselets, perigynous

Morphology Reproductive morphology Flowers Corolla

Petals present (or absent but not in tropical Africa), clasping the stamens or at least at some stages clasping the filaments

Morphology Reproductive morphology Flowers Disc

Disk usually thickened near, but never coherent to, the sides of the ovary

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary 2–4-celled (3 cells are very rare and 4 cells absent in East Africa)

Morphology Reproductive morphology Fruits

Fruit a drupe with a single stone; cells 2 or 3 (or 4 but not in East Africa).

Timothy M. A. Utteridge and Laura V. S. Jennings (2022). Trees of New Guinea. Kew Publishing. Royal Botanic Gardens, Kew

Distribution

About 100 species: mainly in tropical and subtropical areas of Asia and the Americas, a few species in Africa and temperate regions; five species in New Guinea with only one of them arborescent: Ziziphus angustifolia (Miq.) Hatus. ex Steenis.

Morphology General Habit

Shrubs or small to large trees to 30 m, many species climbing, often spiny

Morphology Leaves Stipules

Stipules present, (usually modified into 1 or 2, erect or recurved spines in the scrambling and climbing species)

Morphology Leaves

Leaves alternate, distinctly triplinerved or rarely pinnately veined, margins entire to serrate

Morphology Reproductive morphology Inflorescences

Inflorescences axillary or more rarely terminal, cymose or thyrsoid

Morphology Reproductive morphology Flowers

Flowers yellow-green, bisexual, 5-merous; calyx tube shallow, lobes ovate-triangular or triangular, adaxially ±distinctly keeled; petals clawed, obovate or spatulate, rarely absent; disk shallow, fleshy, 5–10-lobed; ovary superior (immersed in the disk), globose, 2–3(–4)-locular; style ±deeply lobed. Fruit a globose to oblong drupe, single-stoned, (1 or) 2- or 3-loculed, base with persistent calyx tube; mesocarp fleshy or soft corky; endocarp cartilaginous or woody

Morphology Reproductive morphology Seeds

Seeds 1 per locule, with a thin, often shining testa.

Ecology

This genus is found in a primary and secondary habitats, but the tree in New Guinea has been collected from rain forest edges in lowland habitats to 250 m (rarely to c. 850 m).

Recognition

Members of the genus are usually scramblers or climbers with spiny stipules and palmately veined leaves, but the tree species in New Guinea have stipules that are not transformed into spines, but can be recognised by the large tree habit, the palmately veined leaves with an asymmetric leaf base, and an indehiscent fleshy drupe which is orange/red when mature.