Centranthus Lam. & DC.

Scientific Description

Family Valerianaceae.

Habit and leaf form. Erect herbs; bearing essential oils (in rhizomes and roots). Annual, or perennial; plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves; when perennial, rhizomatous (the rhizome usually strongly scented). Stem growth conspicuously sympodial, or not conspicuously sympodial. Helophytic to mesophytic. Leaves opposite; petiolate, or sessile (upper leaves); connate, or not connate; foetid, or without marked odour; simple. Leaf blades entire; flat; pinnately veined; cross-venulate. Leaves without stipules; without a persistent basal meristem. Leaf anatomy. Hydathodes present, or absent. Hairs absent. Stem anatomy. Nodes tri-lacunar. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite (protandrous). Unisexual flowers absent. Plants hermaphrodite. Entomophilous (long-tongued insects).

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in cymes. The terminal inflorescence unit cymose. Inflorescences without involucral bracts. Flowers bracteate; bracteolate; small; fragrant, or malodorous; very irregular; zygomorphic. The floral asymmetry involving the perianth and involving the androecium. Flowers cyclic; tetracyclic. Free hypanthium absent. Perianth with distinct calyx and corolla; 10–30; 2 -whorled; isomerous, or anisomerous. Calyx 5–25; represented by bristles (ultimately); 1 -whorled; gamosepalous (represented by up to 5–25 segments that are inrolled at anthesis to form a ring around the base of the corolla, unrolling and expanding in the fruit to become setaceous, plumose and pappuslike); lobed (much reduced at anthesis); persistent; accrescent. Epicalyx absent. Corolla 5; 1 -whorled; gamopetalous; imbricate; unequal but not bilabiate (zygomorphic); pink to red; spurred, or not spurred (the tube gibbous near the middle or spurred near the base, with an internal longitudinal membrane extending from the spur to the mouth of the corolla tube). Androecium 1. Androecial members adnate. Stamens 1 (the posterior only); becoming exserted; reduced in number relative to the adjacent perianth; oppositisepalous. Anthers dorsifixed; dehiscing via longitudinal slits; introrse; tetrasporangiate. Gynoecium 3 carpelled. The pistil 3 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synstylovarious to eu-syncarpous; inferior. Ovary plurilocular; 3 locular (but only one of the three locules fertile). Gynoecium stylate. Styles 1; apical. Stigmas 1; 3 - lobed. Placentation apical. Ovules 1 per locule; pendulous; non-arillate; anatropous.

Fruit and seed features. Fruit non-fleshy; not hairy; indehiscent; achene-like (dorsiventrally compressedd, crowned by the plumose calyx); 1 seeded. Seeds non-endospermic. Embryo well differentiated. Cotyledons 2. Embryo straight. Seedling. Germination phanerocotylar.

Physiology, biochemistry. Aluminium accumulation not found.

Geography, cytology, number of species. Adventive. Australian states and territories: Western Australia. South-West Botanical Province.