Habit and leaf form. Herbs. Annual, or perennial, or biennial (rarely); plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves; to 0.7 m high. Mesophytic. Leaves minute to medium-sized; on non-flowering shoots at base of plant whorled, or alternate (on flowering stems), or opposite (on overwintering branches); when alternate spiral, or four-ranked; ‘herbaceous’, or leathery, or membranous; sessile (to stem-clasping); simple; epulvinate. Leaf blades entire; linear, or ovate, or elliptic; pinnately veined. Mature leaf blades adaxially glabrous; abaxially glabrous. Leaves without stipules. Leaf blade margins entire. Leaves without a persistent basal meristem. Leaf anatomy. Hydathodes present (occasionally), or absent. Hairs absent. Stem anatomy. Secondary thickening developing from a conventional cambial ring.
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous.
Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in racemes, or in spikes. The terminal inflorescence unit cymose, or racemose. Inflorescences terminal. Flowers pedicellate to sessile; bracteate; ebracteolate; minute to medium-sized; very irregular; zygomorphic; 5 merous; tetracyclic. Free hypanthium absent. Hypogynous disk present. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; gamosepalous; lobed. Calyx lobes markedly longer than the tube. Calyx imbricate, or valvate; unequal but not bilabiate, or regular; persistent; with the median member posterior. Corolla present; 5; 1 -whorled; gamopetalous; lobed; imbricate, or valvate; tubular; bilabiate; hairy adaxially; plain, or with contrasting markings; white, or yellow, or orange, or pink, or purple, or violet, or blue; spurred (basally). Androecium 4. Androecial members adnate (to the corolla); markedly unequal; free of one another; 1 -whorled. Stamens 4; remaining included; didynamous; reduced in number relative to the adjacent perianth; oppositisepalous. Anthers dehiscing via longitudinal slits; introrse; unilocular, or bilocular; tetrasporangiate. Gynoecium 2 carpelled. The pistil 2 celled. Gynoecium non-petaloid; syncarpous; synstylovarious to eu-syncarpous; superior. Ovary plurilocular; 2 locular. Gynoecium median; stylate. Styles 1; attenuate from the ovary, or from a depression at the top of the ovary; apical. Stigmas 1; 1–2 - lobed. Placentation axile, or apical. Ovules 50 per locule (to ‘many’); pendulous to ascending; non-arillate; anatropous, or campylotropous, or hemianatropous.
Fruit and seed features. Fruit non-fleshy; dehiscent; a capsule. Capsules splitting irregularly (via vertical slits in upper half). Fruit 50 seeded (to ‘many’). Seeds endospermic. Endosperm oily. Seeds minute to small; winged, or wingless. Cotyledons 2. Embryo straight to curved.
Special features. Corolla tube exceeding the calyx, or not exceeding the calyx; straight. The upper lip of the corolla incorporating 2 members, the lower 3; (posterior, adaxial) lip of the corolla bilobed; upper (adaxial) lip of the corolla not concave. Lower (abaxial) lip of the corolla 3 lobed (with palate usually closing the throat).
Geography, cytology, number of species. Adventive. Australian states and territories: Western Australia, Queensland, New South Wales, and Victoria.
Etymology. From the Latin for "flax"; refers to the flax-like leaves.