Regelia Schauer

Scientific Description

Common name. Regelias. Family Myrtaceae.

Habit and leaf form. Trees, or shrubs; evergreen; bearing essential oils. Plants with neither basal nor terminal concentrations of leaves; to 1–6 m high. Leptocaul. Helophytic to xerophytic. Heterophyllous, or not heterophyllous. Leaves minute to small; alternate, or opposite; spiral; decussate; ‘herbaceous’, or leathery; sessile; connate, or not connate; gland-dotted; aromatic; edgewise to the stem, or with ‘normal’ orientation; simple; peltate (and stem-clasping), or not peltate; epulvinate. Leaf blades dorsiventral, or isobilateral, or centric; entire; flat, or rolled, or solid; terete, or semi-terete, or solid/angular; linear, or lanceolate, or oblong, or ovate; ovate, or obovate, or triangular, or orbicular; often distinctly 5 -nerved; pinnately veined, or parallel-veined, or one-veined; cross-venulate, or without cross-venules. Leaves without stipules, or with stipules; without a persistent basal meristem. Stem anatomy. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite, or functionally male. Unisexual flowers present, or absent. Plants usually andromonoecious. Entomophilous, or ornithophilous. Pollination mechanism unspecialized.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’. Inflorescence many-flowered. Flowers in spikes, or in heads. Inflorescences simple, or compound. The terminal inflorescence unit cymose. Inflorescences initially terminal (but the central axis soon growing out into a leafy branch); with involucral bracts, or without involucral bracts; pseudanthial. Flowers sessile; bracteate (one bract subtending each flower); (bi) bracteolate, or ebracteolate; small; not operculate; regular; 5 merous; cyclic. Free hypanthium present (petals ‘inserted on the calyx’); cup-shaped; white-hairy. Hypogynous disk present. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; polysepalous, or gamosepalous (depending on interpetation); imbricate, or valvate; regular. Corolla present; 5; 1 -whorled; polypetalous; imbricate; regular; hairy abaxially (ciliate on margin), or glabrous abaxially; hairy adaxially (ciliate on margin), or glabrous adaxially; pink to purple, or red; not fleshy (somewhat scarious). Androecial members indefinite in number. Androecium 60–175. Androecial members branched. Androecial sequence determinable, or not determinable. Androecial members maturing centripetally; free of the perianth; all equal; coherent (forming staminal claws); 5 - adelphous. The androecial groups opposite the petals. Stamens 60–175; attached on the rim of the hypanthium; becoming exserted; all more or less similar in shape; polystemonous; alternisepalous; all opposite the corolla members; erect in bud, or inflexed in bud. Filaments not geniculate. Anthers all alike; dorsifixed, or basifixed; straight (erect); non-versatile (immobile (usually) to partly mobile (in R. punicea); dehiscing via longitudinal slits (slits may be slightly oblique); latrorse; cells back to back but separated at the base; tetrasporangiate; appendaged, or unappendaged. Fertile gynoecium present, or absent. Gynoecium 3 carpelled. The pistil 3 celled. Gynoecium syncarpous; eu-syncarpous; inferior, or partly inferior. Ovary plurilocular; 3 locular. Ovary summit hairy, the hairs not confined to radiating bands (and convex). Epigynous disk absent. Gynoecium stylate. Styles 1; simple; from a depression at the top of the ovary; apical. Stigmas 1. Placentation axile. Ovules 4 per locule (often one of the lower ovules sterile, and develops as a false septum which elongates between the seeds); horizontal (paired, in the peltate placenta); non-arillate; anatropous.

Fruit and seed features. Fruit non-fleshy (woody); dehiscent; a capsule (3-valved). Capsules septicidal, or loculicidal, or denticidal, or circumscissile. Fruit with few fertile seeds. Seeds non-endospermic; wingless. Cotyledons 2.

Geography, cytology, number of species. Native of Australia. Endemic to Australia. Australian states and territories: Western Australia and Northern Territory (R. punicea). South-West Botanical Province. X=11.

Etymology. After Eduard August von Regel (1815–92), superintendent of the botanical gardens at Leningrad (then St Petersburg).