Isopogon Knight

Scientific Description

Common name. Coneflower. Family Proteaceae.

Habit and leaf form. Small trees, or shrubs; evergreen. To 0.4–5 m high. Mesophytic, or xerophytic. Heterophyllous, or not heterophyllous. Leaves small to very large; alternate; leathery; petiolate to sessile; edgewise to the stem, or with ‘normal’ orientation; simple, or compound, or simple and compound (with compound leaves on outside of the cluster); epulvinate; ternate, or pinnate, or bipinnate. Leaflets linear. Leaf blades when simple, dissected, or entire; flat, or solid; terete; linear, or obovate, or oblong; when simple/dissected pinnatifid, or palmately lobed, or dichotomously dissected, or much-divided, or spinose. 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. 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 aggregated in ‘inflorescences’; not in pairs subtended by a common bract; in spikes, or in heads. Inflorescences terminal, or axillary; dense, more or less globose or ovoid, sessile or pedunculate, solitary or several-clustered; usually with involucral bracts, or without involucral bracts. Involucral bracts persistent (more so than the cone scales). Inflorescences pseudanthial. The fruiting inflorescence conelike. Flowers sessile; bracteate (becoming cone scales), or ebracteate (depending on interpretation); small to medium-sized; regular; 4 merous; cyclic; tetracyclic. Floral receptacle developing a gynophore, or with neither androphore nor gynophore. Free hypanthium absent. Hypogynous disk absent. Perianth of ‘tepals’; 4; 1 -whorled; joined (basally, spreading at anthesis); hairy, or glabrous; white, or cream, or yellow, or red, or pink, or purple; persistent (or at least the basal part of the tepal persistent until the fruit expands on ripening). Androecial members definite in number. Androecium 4. Androecial members adnate (to tepals); all equal; free of one another; 1 -whorled. Stamens 4; isomerous with the perianth; with sessile anthers (with short connective). Anthers basifixed; non-versatile; dehiscing via longitudinal slits; introrse; four locular; tetrasporangiate. Gynoecium 1 carpelled. The pistil 1 celled. Gynoecium monomerous; of one carpel; superior. Carpel stylate; apically stigmatic. Style straight (the pollen presenter usually dilated or clavate, often separated from the brush by a constriction, with various parts glabrous or hairy, rarely fusiform, with a very small stigma, otherwise the tip slightly enlarged to form a stigmatic cup). Carpel 1(–2) ovuled. Placentation marginal, or apical. Ovary sessile. Ovules funicled, or sessile; pendulous; non-arillate; orthotropous, or anatropous, or amphitropous, or hemianatropous.

Fruit and seed features. Fruit falling from the plant before the next growing season; non-fleshy; hairy. The fruiting carpel indehiscent; nucular (small, not compressed or winged). Endocarp frequently crystalliferous. Seeds non-endospermic. Embryo well differentiated. Cotyledons 2(–8). Embryo straight.

Special features. Cone scales falling prior to or at the same time as the nuts. Stamens inserted within a concavity near the end of a perianth segment.

Geography, cytology, number of species. Native of Australia. Endemic to Australia. Australian states and territories: Western Australia, South Australia, Queensland, New South Wales, and Victoria. Eremaean Botanical Province and South-West Botanical Province. N=13.

Etymology. From the Greek for "equal" and "beard", referring to the tufts of hairs at the apex of the perianth segments of some species or, possibly, referring to the hairs of more or less equal length which cover the nut on all sides.