Discocalyx (A.DC.) Mez

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

Distribution

A small genus of c. 25 species from the Philippines through to the Pacific; 13 currently recognised from New Guinea.

Morphology General Habit

Shrubs or small trees to 8(–25) m (in New Guinea)

Morphology Leaves

Leaves alternate, crowded at the distal ends of stems or branches, entire or rarely crenulate, punctate; petiole with pulvinus

Morphology Reproductive morphology Inflorescences

Inflorescences axillary, racemose or compound racemose

Morphology Reproductive morphology Flowers

Flowers 4–5-merous, unisexual rarely bisexual (plants usually dioecious); calyx imbricate in bud, fused for ⅔ of their length, punctate; corolla urceolate to campanulate, lobes dextrorsely imbricate in bud, punctate; stamens in staminate flowers with filaments fused at the base, anthers free, basifixed; staminodes present in pistillate flowers as reduced stamens or fleshy swellings; pistillode present in staminate flowers, conical, hollow or with a few abortive ovules; pistillate flowers with ovary ovoid to obturbinate, ovules few (usually 3–5), uniseriate; style distinct but often short, the stigma peltate to discoid, persistent in fruit

Morphology Reproductive morphology Fruits

Fruit oblongoid to subglobose, wider than long, exocarp thin

Morphology Reproductive morphology Seeds

Seed 1.

Ecology

Members of Discocalyx are usually found in the understorey or undergrowth of primary forest, in lowland, montane and mossy forest from sea level to 2000(–3000) m.

Recognition

The genus can be recognised by the leaves which are usually crowded at the apex of the stem or branches, the unisexual flowers which can be 4- or 5-merous, the short style with a peltate to discoid stigma and the fruit with a thin exocarp. Discocalyx is rather similar to Fittingia, but differs primarily in the thin exocarp of the fruit (rather than a fleshy/spongy exocarp in Fittingia), and a smooth endocarp (rather than being ridged or tubercled as in Fittingia); in addition, the inflorescence of Discocalyx is usually erect whereas that of Fittingia is pendulous.