Family Rhodoleiaceae

Rhodoleiaceae (Harms) Nak.

~ Hamamelidaceae

Habit and leaf form. Trees, or shrubs (of rhododendroid habit). Leaves evergreen (glaucous beneath); alternate (crowded towards the branch tips); spiral; leathery; long petiolate; non-sheathing; simple. Lamina entire; ovate; pinnately veined; cross-venulate; rarely cordate. Leaves exstipulate (as usually described), or stipulate (in respect of the transitional organs between prophylls and leaves). Lamina margins entire.

Leaf anatomy. Stomata present; paracytic.

Lamina dorsiventral. The mesophyll with sclerencymatous idioblasts (these branched, but short and gnarled).

Stem anatomy. Cork cambium present. Cortical bundles absent. Medullary bundles absent. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. ‘Included’ phloem absent. Vessel end-walls scalariform.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Floral nectaries present. Nectar secretion from small nectariferous glands around the filaments. Pollination ornithophilous.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in heads. Inflorescences axillary; 5–10 flowered axillary, pendulous capitula; with involucral bracts (these usually broad, imbricate, tomentose); pseudanthial (simulating Camellia flowers). Flowers cyclic; tetracyclic, or pentacyclic. Free hypanthium absent.

Perianth with distinct calyx and corolla, or sepaline (the inner florets of the capitula being apetalous); 5–9; 1 whorled (when the corolla absent), or 2 whorled; anisomerous. Calyx 5; 1 whorled; gamosepalous (minute). Corolla when present, 1–4; polypetalous; imbricate; red. Petals clawed (spathulate, exserted).

Androecium (7–)10(–11). Androecial members free of the perianth; free of one another. Androecium exclusively of fertile stamens. Stamens (7–)10(–11); diplostemonous to polystemonous. Anthers basifixed; oblong, non-versatile; dehiscing by longitudinal valves; latrorse; appendaged. The anther appendages apical (via the apiculate connective). Pollen grains aperturate; 3 aperturate; colpate, or colporate (?).

Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth, or isomerous with the perianth. The pistil 1–2 celled. Gynoecium syncarpous; synovarious; partly inferior (sometimes glaucous). Ovary 1–2 locular. Gynoecium stylate. Styles 2 (these long, slender, erect, caducous); free; apical. Stigmas 2. Placentation axile. Ovules 1–20 per locule; more or less horizontal.

Fruit non-fleshy; dehiscent; a capsule (woody, usually bilocular). Capsules four valvular (connate below). Gynoecia of adjoining flowers combining to form a multiple fruit. Fruit 1 seeded (with an additional 20–40 sterile, angular or flattened seeds). Seeds copiously endospermic.

Geography, cytology. Paleotropical. Tropical. Southeast Asia, Malesia. X = 12.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rosiflorae; Hamamelidales. Cronquist’s Subclass Hamamelidae; Hamamelidales. APG 3 core angiosperms; core eudicot; unplaced at Superordinal level; Order Saxifragales (as a synonym of Hamamelidaceae).

Species 1(–7). Genera 1; only genus, Rhodoleia.

Illustrations.
• Rhodoleia: flower.