Common name. Mudworts. Family Scrophulariaceae.
Habit and leaf form. Herbs. Annual, or perennial. Leaves basal (by suppression of internodes), or cauline (rarely). Plants with a basal concentration of leaves. Hydrophytic, or helophytic; when hydrophytic, rooted. Leaves of aquatics floating; small to medium-sized; alternate (on short branches), or opposite (on new stolons); when alternate spiral, or four-ranked; ‘herbaceous’, or leathery, or membranous; petiolate; simple; epulvinate. Leaf blades entire; obovate, or oblong, or elliptic; palmately 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 solitary; axillary; pedicellate to sessile; ebracteate; ebracteolate; minute to small; regular, or somewhat irregular; tetracyclic. Free hypanthium absent. Hypogynous disk present. Perianth with distinct calyx and corolla; (7–)10; 2 -whorled; isomerous, or anisomerous. Calyx present; (3–)5; 1 -whorled; gamosepalous; lobed. Calyx lobes markedly shorter than the tube. Calyx imbricate, or valvate; campanulate, or tubular; regular, or unequal but not bilabiate; persistent; accrescent; when K5, with the median member posterior. Calyx lobes triangular. Corolla present; 4, or 5; 1 -whorled; gamopetalous; lobed. Corolla lobes markedly longer than the tube. Corolla imbricate, or valvate; rotate and campanulate; more or less regular; hairy adaxially; plain; white, or pink, or purple. Corolla lobes ovate. Androecium 4. Androecial members adnate (to the corolla); all equal; free of one another; 1 -whorled. Stamens 4; becoming exserted; all more or less similar in shape; reduced in number relative to the adjacent perianth, or isomerous with the perianth; oppositisepalous. Anthers dehiscing via longitudinal slits; introrse; unilocular; 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; simple; attenuate from the ovary, or from a depression at the top of the ovary; apical. Stigmas 1; 1 - lobed, or 2 - lobed (obscurely); capitate. 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 septicidal (by 2 valves), or valvular (septum incomplete (absent in the upper half) with remnants attached to central column). Fruit 50 seeded (to ‘many’). Seeds endospermic. Endosperm oily. Seeds minute to small. Cotyledons 2. Embryo straight to curved.
Special features. Corolla tube straight.
Geography, cytology, number of species. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia, South Australia, Queensland, New South Wales, Victoria, Australian Capital Territory, and Tasmania. South-West Botanical Province.
Etymology. From the Latin for "muddy" and the diminutive suffix -ell-; refers to the habitat.