Mimulus L.

Scientific Description

Common name. Monkey-flowers. Family Scrophulariaceae.

Habit and leaf form. Herbs. Annual, or perennial; plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves; to 0.35 m high. Hydrophytic, or helophytic, or mesophytic; when hydrophytic, rooted. Leaves of aquatics submerged, or emergent; minute to medium-sized; opposite, or whorled; ‘herbaceous’, or leathery, or membranous; petiolate to sessile; connate, or not connate; aromatic, or without marked odour; simple; epulvinate. Leaf blades entire; linear, or ovate, or oblong, or elliptic; pinnately veined; cordate, or attenuate at the base, or cuneate at the base, or rounded at the base. Mature leaf blades adaxially glabrous, or pubescent, or villous; abaxially glabrous, or pubescent, or villous. Leaves without stipules. Leaf blade margins entire, or serrate, or dentate. Leaves without a persistent basal meristem. Leaf anatomy. Hydathodes present (occasionally), or absent. Hairs present, or absent; glandular hairs present, or 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, or aggregated in ‘inflorescences’; axillary; in racemes. The terminal inflorescence unit cymose, or racemose. Inflorescences terminal, or axillary. Flowers pedicellate; bracteate; ebracteolate; small to medium-sized; regular, or 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; toothed. Calyx lobes markedly shorter than the tube. Calyx erect; imbricate, or valvate; campanulate, or tubular; regular, or unequal but not bilabiate (lobes slightly unequal); persistent; accrescent; with the median member posterior. Corolla present; 5; 1 -whorled; gamopetalous; lobed; imbricate, or valvate; when regular, rotate; regular, or bilabiate; hairy abaxially, or glabrous abaxially; hairy adaxially, or glabrous adaxially; plain, or with contrasting markings; white, or yellow, or red, or pink, or purple, or blue. Androecium 4. Androecial members adnate (to the corolla); markedly unequal; coherent (paired anthers connate); 1 -whorled. Stamens 4; all inserted at the same level; remaining included; didynamous; all more or less similar in shape; reduced in number relative to the adjacent perianth; oppositisepalous. Anthers cohering (in pairs); dehiscing via longitudinal slits; introrse; bilocular (cells confluent but divergent); 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; 2 - lobed (lobes equal or unequal, receptive on the inner surface, closing together when touched). 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 loculicidal (with the septa remaining attached to the 2 valves or to the central placental column), or septicidal and loculicidal (into 4 valves). Fruit 50 seeded (to ‘many’). Seeds endospermic. Endosperm oily. Seeds minute. Cotyledons 2. Embryo straight to curved.

Special features. Corolla tube exceeding the calyx; straight. The upper lip of the corolla incorporating 2 members, the lower 3; (posterior, adaxial) lip of the corolla bilobed. Lower (abaxial) lip of the corolla 3 lobed.

Geography, cytology, number of species. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia, South Australia, Northern Territory, Queensland, New South Wales, Victoria, Australian Capital Territory, and Tasmania. Northern Botanical Province.

Etymology. From the Latin mimulus; a diminutive of mimus (a mimic actor); refers to the mask-like appearance of the flowers.