Common name. Watsonias. Family Iridaceae.
Habit and leaf form. Herbs (medium to large); evergreen, or deciduous. Perennial (annual leaves and flowers). Leaves basal and cauline. Plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves; cormous (large, depressed-globose; tunic coarsely fibrous). Helophytic to xerophytic. Leaves alternate; distichous; ‘herbaceous’, or leathery; sessile; sheathing. Leaf sheaths with free margins. Leaves foetid, or without marked odour; edgewise to the stem, or with ‘normal’ orientation; simple; epulvinate. Leaf blades entire; flat, or solid; linear, or lanceolate; basal leaves linear (to enisform); parallel-veined; without cross-venules; open or closed sheaths. Leaves eligulate; without stipules. Leaf blade margins entire. Leaves with a persistent basal meristem, and basipetal development. Leaf anatomy. Hairs absent. Extra-floral nectaries absent. Stem anatomy. Secondary thickening absent.
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Floral nectaries present, or absent. Nectar secretion from the gynoecium (septal nectaries). Entomophilous, or ornithophilous, or anemophilous.
Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in cymes, or in spikes (or spike-like). The terminal inflorescence unit cymose, or racemose. Inflorescences terminal; inflorescence axis straight, erect, branched or unbranched; inflorescence loosely distichous, many-flowered; spatheate (via expanded, bladeless sheaths). Flowers sessile; bracteate (2 enclose each flower, inserted at the base of the ovary, spathe-like, persistent, herbaceous or dry or scarious; outer bract undivided). Bracts persistent. Flowers ebracteolate; small to large; regular, or somewhat irregular, or very irregular; when irregular, zygomorphic; 3 merous; cyclic; tetracyclic. Perigone tube present (tubular). Perianth of ‘tepals’; 6; 2 -whorled; isomerous; petaloid; without spots, or spotted; similar in the two whorls, or different in the two whorls; green, or orange, or red, or pink (or mauve). Androecial members definite in number. Androecium 3, or 6. Androecial members adnate; all equal; free of one another, or coherent (rarely); when united, 1 - adelphous; 1 -whorled (representing the outer whorl). Androecium exclusively of fertile stamens, or including staminodes. Stamens 3; all more or less similar in shape; reduced in number relative to the adjacent perianth to isomerous with the perianth; on the perianth tube opposite the outer segments; alterniperianthial (opposite the outer perianth lobes). Anthers basifixed (or sub-basifixed); dehiscing via longitudinal slits; extrorse. Gynoecium 3 carpelled. The pistil 3 celled. Gynoecium partly petaloid, or non-petaloid; syncarpous; synstylovarious; inferior. Ovary plurilocular; 3 locular. The ‘odd’ carpel anterior. Gynoecium stylate. Styles 1; apical. Stigmas 6 (or 3). Placentation axile. Ovules 20–50 per locule (many); arillate, or non-arillate; anatropous.
Fruit and seed features. Fruit non-fleshy; dehiscent; a capsule. Capsules loculicidal (from the apex). Fruit 3 celled; 20–100 seeded (many). Seeds endospermic. Endosperm oily. Cotyledons 1 (coleoptile-like). Embryo straight (small). Testa without phytomelan.
Etymology. After Sir William Watson (1715–87), English student of electricity, apothecary; physician and botanist.