Peplidium Delile

Scientific Description

Common name. Peplidiums. Family Scrophulariaceae.

Habit and leaf form. Herbs. Annual, or perennial; plants with neither basal nor terminal concentrations of leaves, or with terminal rosettes of leaves (P. aithocheilum). Hydrophytic, or helophytic, or mesophytic; when hydrophytic, rooted. Leaves of aquatics floating; minute to small; opposite; fleshy; petiolate; connate (by a ridge across the node); simple; epulvinate. Leaf blades entire; ovate, or obovate, or elliptic, or orbicular; pinnately veined. Mature leaf blades adaxially glabrous, or pubescent; abaxially glabrous, or pubescent. Leaves without stipules. Leaf blade margins entire. Leaves without a persistent basal meristem. Leaf anatomy. Hydathodes present (occasionally), or absent. Hairs present, or absent; glandular 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, or aggregated in ‘inflorescences’; in racemes. The terminal inflorescence unit cymose, or racemose. Inflorescences terminal; raceme-like or flowers scattered, the flowers one to a few in clusters in leaf or bract axils. Flowers pedicellate to sessile; bracteate; ebracteolate; small; more or less 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. Calyx lobes markedly shorter than the tube. Calyx erect; imbricate, or valvate; campanulate, or tubular; regular; persistent; accrescent; with the median member posterior. Corolla present; 5; 1 -whorled; gamopetalous; lobed. Corolla lobes markedly shorter than the tube (lobes obscure), or about the same length as the tube (and showy). Corolla imbricate, or valvate; when regular, more or less rotate; regular, or bilabiate; with contrasting markings; white, or red, or pink, or purple, or blue, or brown; persistent, or deciduous. Androecium 2, or 4. Androecial members adnate (to the corolla); all equal (when only 2 present), or markedly unequal (when 4); coherent; 1 -whorled. Stamens 2, or 4; becoming exserted, or remaining included; didynamous; reduced in number relative to the adjacent perianth; oppositisepalous. Anthers cohering (in pairs); 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; attenuate from the ovary, or from a depression at the top of the ovary; apical; persistent. Stigmas 1; 1 - lobed (lobe flap-like, covering the corolla mouth above the anthers, receptive on the upper surface, irritable, when touched bending back against the upper corolla lip), or 2 - lobed (vestigial second flap at base). 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; not hairy; not spinose; dehiscent; a capsule. Capsules tardily septicidal and loculicidal (from the base upwards), or loculicidal (from the apex). Fruit 50 seeded (to ‘many’). Seeds endospermic. Endosperm oily. Seeds minute, or small. Cotyledons 2. Embryo straight to curved.

Special features. Corolla tube not 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, and New South Wales. Northern Botanical Province and Eremaean Botanical Province.

Etymology. From the Latin for "spurge", Euphorbia peplis and the diminutive suffix -idium.