Myoporum G.Forst.

Scientific Description

Common name. Myoporums. Family Myoporaceae.

Habit and leaf form. Small trees, or shrubs; deciduous; resinous (to viscid). Young stems cylindrical. To 0.3–20 m high. Mesophytic, or xerophytic. Leaves minute to medium-sized; alternate, or opposite (rarely); usually spiral; ‘herbaceous’, or leathery, or fleshy; petiolate, or sessile; non-sheathing; gland-dotted; simple; epulvinate. Leaf blades entire; linear, or ovate, or obovate, or oblong. Mature leaf blades glabrous, or pubescent (rarely). Leaves without stipules. Leaf blade margins entire, or serrate, or dentate. Leaves without a persistent basal meristem. Stem anatomy. Nodes unilacunar. Secondary thickening developing from a conventional cambial ring.

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

Inflorescence and flower features. Flowers solitary (rarely), or aggregated in ‘inflorescences’ (usually, by contrast with Eremophila); axillary. Inflorescence few-flowered to many-flowered. Flowers when aggregated, in cymes. The terminal inflorescence unit cymose. Inflorescences axillary; the flowers opening more or less simultaneously. Flowers pedicellate; ebracteate; small (less than 8 mm long — i.e. smaller than in Eremophila); almost regular to very irregular; slightly zygomorphic; more or less 5 merous; cyclic; tetracyclic. Free hypanthium absent. Perianth with distinct calyx and corolla; (9–)10; 2 -whorled; isomerous, or anisomerous (rarely). Calyx present; (4–)5; 1 -whorled; basally gamosepalous, or polysepalous; lobed; imbricate, or valvate; regular, or unequal but not bilabiate (subequal); persistent; non-accrescent; with the median member posterior. Calyx lobes ovate to triangular. Corolla present; (4–)5(–6); 1 -whorled; gamopetalous; lobed. Corolla lobes markedly shorter than the tube, or about the same length as the tube, or markedly longer than the tube. Corolla imbricate; campanulate; almost regular, or bilabiate (abaxial lobes somewhat larger); glabrous abaxially; hairy adaxially, or glabrous adaxially; plain, or with contrasting markings; often white, or pink to purple (tinged). Androecial members definite in number. Androecium (3–)4(–5). Androecial sequence not determinable. Androecial members adnate (to the corolla tube); all equal (nearly always), or markedly unequal (M. beckeri); free of one another; 1 -whorled. Androecium exclusively of fertile stamens (the upper, posterior member usually lacking). Stamens (3–)4(–5); becoming exserted, or remaining included; of M. beckeri didynamous; reduced in number relative to the adjacent perianth, or isomerous with the perianth (rarely); fertile stamens representing the posterior-lateral pair and the anterior-lateral pair; oppositisepalous. Filaments hairy, or glabrous. Anthers separate from one another; dorsifixed; straight, or recurved; versatile; dehiscing via longitudinal slits; introrse; unilocular (the cells confluent). Gynoecium 2 carpelled. The pistil 2 celled, or 3–10 celled (by secondary segmentation of the locules). Carpels reduced in number relative to the perianth. Gynoecium syncarpous; eu-syncarpous; superior. Ovary plurilocular; 2 locular. Locules secondarily divided by ‘false septa’, or without ‘false septa’. Gynoecium median. Ovary sessile. Gynoecium stylate. Styles 1 (straight); from a depression at the top of the ovary; apical; hairy, or hairless. Stigmas 1; 1–2 - lobed (? notched at apex); dry type; papillate; Group II type. Placentation axile, or apical, or axile to apical. Ovules 1–2 per locule; funicled; pendulous; non-arillate; anatropous.

Fruit and seed features. Fruit fleshy, or non-fleshy (rarely); indehiscent; a drupe. The drupes with separable pyrenes (the segments one-seeded). Fruit 2–10 celled; 2–10 locular; 2–10 seeded. Seeds 1 per locule. Seeds scantily endospermic, or non-endospermic. Cotyledons 2. Embryo more or less straight. Seedling. Germination phanerocotylar.

Physiology, biochemistry. Aluminium accumulation not found.

Special features. Corolla tube more or less straight.

Geography, cytology, number of species. X = 27.

Economic uses, etc. Myoporum species show significant horticultural potential and are good sources of sesquiterpenes (Richmond & Ghisalberti, 1995).

Etymology. From the Greek for "to be shut or closed" and "pore"; refers to the closed appearance of the glands on the leaves.