Psammomoya Diels & Loes.

Scientific Description

Family Celastraceae.

Habit and leaf form. Shrubs (subshrubs); laticiferous, or non-laticiferous and without coloured juice. Switch-plants; with the principal photosynthesizing function transferred to stems. Leaves much reduced (to cataphylls). Plants spiny, or unarmed. The spines axial (the branch tips). Leaves cauline. Young stems tetragonal (4 sulcate). Stem internodes solid. Leaves opposite; decussate; ‘herbaceous’, or leathery, or membranous; sessile; simple; without a persistent basal meristem. Leaf anatomy. Hairs absent. Extra-floral nectaries absent.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous.

Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; axillary. Inflorescence few-flowered. Flowers in fascicles. Inflorescences axillary (axils of cataphylls); few-flowered. Flowers pedicellate; ebracteate; bracteolate (at base of pedicels). Bracteoles persistent. Flowers usually small; regular; 4–5 merous; cyclic; nearly always tetracyclic. Hypogynous disk present; intrastaminal; annular. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; gamosepalous (basally connate); blunt-lobed; imbricate; exceeded by the corolla; regular; green, or cream, or yellow; non-fleshy; persistent. Calyx lobes ovate to triangular (to broadly deltoid). Corolla present; 5; 1 -whorled; polypetalous; imbricate; regular; glabrous abaxially; glabrous adaxially; green, or white, or cream; persistent. Petals oblong to ovate, or triangular (to narrowly deltoid). Fertile stamens present. Androecial members definite in number. Androecium 5. Androecial members free of the perianth; all equal; free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 5; all more or less similar in shape; isomerous with the perianth; oppositisepalous. Filaments glabrous. Anthers basifixed; non-versatile; dehiscing via longitudinal slits; introrse; bilocular; bisporangiate, or tetrasporangiate. Pollen shed in aggregates, or shed as single grains; when in aggregates in tetrads, or in polyads. Fertile gynoecium present. Gynoecium 2–3 carpelled (the third when present sometimes abortive). The pistil 2–3 celled. Carpels reduced in number relative to the perianth, or isomerous with the perianth. Gynoecium syncarpous; synstylovarious; superior (although with disk adnate to the lower part). Ovary plurilocular; 2–3 locular; sessile. Gynoecium stylate. Styles 1; attenuate from the ovary; apical. Stigmas 1; obscurely 2–3 - lobed. Placentation axile. Ovules 2 per locule; pendulous, or ascending; apotropous; with ventral raphe, or with dorsal raphe (when pendulous); anatropous.

Fruit and seed features. Fruit non-fleshy; not hairy; dehiscent; a capsule. Capsules loculicidal. Fruit 2–3 celled; 2–3 locular; 2–6 seeded. Seeds endospermic. Endosperm when present, ‘more or less’ oily. Seeds small; arillate; wingless. Embryo well differentiated. Cotyledons 2 (large, flat, foliaceous). Embryo straight. Testa smooth; brown.

Geography, cytology, number of species. World distribution: south western Australia. Native of Australia. Endemic to Australia. Australian states and territories: Western Australia. Eremaean Botanical Province and South-West Botanical Province. A genus of 4 species; 4 species in Western Australia; 4 endemic to Western Australia.

Etymology. From the Greek for "sand" and "near, hard by".