Pilidiostigma Burret

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

Distribution

A genus of six species, the distribution is chiefly Australian with one species extending into New Guinea: Pilidiostigma papuanum (Lauterb.) A.J.Scott.

Morphology General Habit

Trees and shrubs to 18 m tall

Morphology Leaves

Leaves opposite, chartaceous, elliptic to ovate, gland dots inconspicuous, pinnate venation, intra-marginal vein usually double

Morphology Reproductive morphology Inflorescences

Inflorescence axillary, racemose or flowers solitary

Morphology Reproductive morphology Flowers

Flowers 4-merous (in New Guinea), white or pink; sepals rounded, free; petals free, concave, reflexed at anthesis; stamens many (up to 250), usually in multiple whorls, numerous glands on anther connectives; style thick, stigma peltate; ovary inferior, 2–3-locular, placentation axile, ovules 1–8 per placenta

Morphology Reproductive morphology Fruits

Fruit a fleshy berry, crowned by persistent calyx lobes, purple or black when mature

Morphology Reproductive morphology Seeds

Seeds 1–5, testa thin, glandular-tuberculate. Embryo curved, with a swollen hypocotyl and much reduced cotyledons.

Ecology

Pilidiostigma has been recorded from rain forests up to 400 m.

Recognition

The genus can be recognised in New Guinea by the opposite leaves which often have a double intra-marginal vein, 4-merous flowers on unbranched inflorescences and the fleshy fruit with 1–5 seeds with glandular seed coats. The genus can be distinguished from Eugenia by the presence of a double intra-marginal vein, the fruit with more than 1 seed and by the curved embryo with obvious cotyledons (embryo homogenous in Eugenia). Pilidiostigma can be distinguished from Gossia by the double intra-marginal vein, peltate stigma (punctate in Gossia) and the glandular seed coat.