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Euphorbiaceae |
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This is a very large and diverse, cosmopolitan family, relatively easily recognised but difficult to characterise. In Australia, members for the family are found in all regions except the high alps, but are most diverse in the eastern and north-eastern tropical rain forests. Relatively few penetrate the arid lands or into temperate regions. Interestingly, for such a large family, very few are weeds - only a few species of Euphorbia and one of Ricinus are naturalised weeds in Australia. Characteristic features of the family Euphorbiaceae in Australia include:
Description
Evergreen or semi-deciduous trees or shrubs, rarely woody or herbaceous vines climbing by twining stems, or annual, biennial or perennial terrestrial herbs. Perennating by taproots or crowns. Leaves present or rarely ±absent. Stem internodes terete, oval or slightly flattened, strongly flattened or distinctly angular. Internal secretions not obvious or of milky sap (latex), or rarely of resin. Plants glabrous or with simple or stellate, non-glandular, unicellular or uniseriate hairs, or glandular hairs present as granular papillae, stinging hairs absent or rarely present, peltate scales rarely present. Leaves well developed, or much reduced (ie. to scales, etc.), or entirely absent, alternate and spiral or distichous, rarely opposite, cauline if herbs, petiolate, subsessile or sessile, or rarely peltate; pulvinae absent or rarely present. Stipules distinct and free from the petiole, or rarely interpetiolar, scale-like or membranous, or lacerate, or fimbriate, persistent or falling off early; stipellae rarely present. Lamina simple, or rarely ternately compound, symmetric or conspicuously asymmetric; lamina/leaflets filiform, acicular, subulate, linear, lanceolate, ovate, elliptic, oblanceolate, obovate, oblong, spathulate or orbicular, or rarely palmatifid or palmatisect; base cuneate, attenuate, rounded, cordate or oblique; margins entire, crenate or serrate, ±flat, revolute, recurved, involute or incurved; one-veined, or the venation pinnate, or rarely palmate, with the midrib conspicuous or inconspicuous, and the tertiary venation reticulate or not; surfaces punctate or not punctate; herbaceous, leathery, membranous or papery; distinctive odour absent or foetid. Male and female flowers occurring on the same plant or on separate plants. Inflorescences terminal, axillary or intercalary, consisting of cyathia, capitula or glomerules, spikes, racemes, corymbs, umbels or solitary flowers. Bracts and bracteoles present, herbaceous. Pollination by insects or wind. Flowers odourless or fragrant, sessile or stalked. Floral disc present or absent; nectaries absent or present on the disc. Perianth of 2 dissimilar whorls, or of 1 whorl only, or all whorls ±similar, or vestigial, or absent, with 0–6 (–10) segments. Calyx regular; segments free or fused, with (0–) 3–6 (–10) sepals or lobes, imbricate, valvate or open in bud; calyx cup-shaped, bell-shaped, urn-shaped, funnel-shaped or rarely tubular, herbaceous; margins entire, lobed or lacerate. Corolla regular, rarely irregular; segments free, with 0 or 4–5 (–6) petals, alternating with the sepals or calyx lobes, imbricate in bud, white, cream, pink or green, without contrasting markings, membranous; claws absent; lobes ±entire. Fertile stamens (1–) 3 (–numerous), opposite to or not clearly correlated with the sepals or calyx lobes, free of the corolla, free of the ovary and style, distinct from each other, fused by their filaments into an open or closed tube or fused by their anthers, all ±equal. Staminodes absent. Staminal filaments present or absent. Anthers dorsifixed, basifixed or apicifixed, not versatile, opening outwards, sideways or inwards by longitudinal slits, rarely by terminal pores or transverse slits, 2- (or 4-) celled; appendages absent or apical. Ovary superior and sessile or stalked. Carpels (2–) 3 (–4), fused; ovary with (1–) 3 (–25) locules. Style terminal, single and unbranched, or branched above or from the base and the stigma clavate, peltate, capitate or truncate. Ovules 1–2 per locule, stalked or sessile; placentation apical or axile. Fruit a dry, dehiscent septicidal or loculicidal capsule sometimes with explosive dehiscence, or a fleshy, indehiscent drupe; the perianth on the maturing fruit deciduous. Disseminule micro-surface ±smooth, echinate, alveolate, tuberculate, muricate, colliculate, papillate, reticulate, sulcate, rugose or verrucose, cream, orange, red, magenta, purple, violet, blue, green, brown or black, glossy or dull. Seeds 1–12 or more per fruit. Aril present or absent. Cotyledons 2. Embryo straight or curved. A treatment of the family Euphorbiaceae has not yet been published in the Flora of Australia. It will appear in Volume 23.
Australian genera of Euphorbiaceae (as recognised for the Flora of Australia)
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 Actephila lindleyi (flowers) Photo: M.Fagg © M.Fagg
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