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Commelinaceae


A moderate-sized, principally pantropical family, these are herbs most of which grow in wet places or areas of high rainfall in rain forests, open forests or along streams. Most Australian species are found in the rainforests of the north-east; one species grows on the arid ranges of Central Australia, while some are introduced weeds of gardens and disturbed places.

Characteristic features of the family Commelinaceae in Australia include:

  • usually somewhat succulent herbs with creeping or erect stems
  • leaves alternate, often ovate and folded, simple, sheathing the stems and with parallel venation
  • flowers often showy, with 3 thin, white or coloured petals, regular or zygomorphic, the base of the flowers sometimes enclosed by a spathe-like bract
  • stamens 6, sometimes arranged asymmetrically and with some reduced to staminodes

Description

Annual or perennial terrestrial herbs, or aquatic herbs rooted in the substrate with their leaves emergent, or rarely herbaceous scrambling vines. Perennating by tubers or rhizomes. Vegetative reproduction by tubers, rhizomes, stolons or by detached stem parts. Stem internodes solid, spongy, pithy or hollow, terete, oval or slightly flattened. Internal secretions of coloured sap. Plants glabrous or with simple, glandular or non-glandular, unicellular or uniseriate hairs. Leaves alternate and spiral, or distichous, cauline, all or mostly basal, or both basal and cauline, sessile. Stipules absent. Lamina simple, symmetric, filiform, acicular, subulate, linear, lanceolate, ovate or elliptic; base attenuate, rounded, cordate or lobed or auriculate; margins entire, ±flat, involute or incurved; venation parallel, with the midrib conspicuous or inconspicuous, and the tertiary venation reticulate or not; surfaces not punctate; herbaceous or succulent. Leaf ligule absent. Plants with all the flowers bisexual, or with female flowers also present. Inflorescences terminal or axillary, consisting of glomerules, spikes, racemes, monochasial cymes or solitary flowers. Spathes present or absent. Bracts present or absent. Pollination by insects. Flowers odourless; sessile or stalked. Floral disc absent; nectaries absent. Perianth regular or irregular, of 2 dissimilar whorls, imbricate in bud. Calyx segments free or fused, with 3 sepals or lobes; calyx funnel-shaped or tubular, herbaceous. Corolla segments free or fused, with 3 petals or lobes, alternating with the sepals or calyx lobes; corolla wheel-shaped, funnel-shaped or tubular, 1-lipped; white, yellow, orange, pink, magenta, purple or blue, without contrasting markings, or streaked, spotted, etc, membranous; claws present or absent; lobes ±entire. Fertile stamens 3 or 6, opposite to the sepals or calyx lobes, free of the perianth, free of the ovary and style, distinct from each other, all ±equal. Staminodes present or absent. Anthers basifixed, versatile or not versatile, opening by pores or inwards by longitudinal slits; 2-celled; with appendages absent or basal. Ovary superior and sessile. Carpels 3, fused; ovary with 3 locules. Style terminal, single and unbranched or single and branched above. Ovules 110 per locule, stalked; placentation axile. Fruit dry or fleshy, dehiscent or indehiscent; a loculicidal capsule, ?balausta (fruit with firm rind and berries within, like a pomegranate) or berry; the perianth on the maturing fruit deciduous, rotting or liquefying or dry and persistent. Disseminule micro-surface ±smooth, spinulose, tuberculate, reticulate, alveolate, rugose, granulate or verrucose, brown, grey or black, without contrasting markings, or conspicuously patterned, dull. Seeds 110 per fruit. Aril absent. Cotyledons 1. Embryo straight.
(Note: this description has been generated from the coded data compiled for the key. Any errors in the key data will be reflected in the descriptions.)

A treatment of the family Commelinaceae has not yet been published in the Flora of Australia. It will appear in Volume 40.

Australian genera of Commelinaceae (as recognised for the Flora of Australia)

* = all species introduced

Aneilema
*Callisia
Cartonema
Commelina
Cyanotis
*Dichorisandra
Floscopa
Murdannia
Pollia
*Tradescantia
*Zebrina


Aneilema acuminatum (flowers)
Photo: M.Fagg M.Fagg 


Cartonema parviflorum (flower)
Photo: J.Wrigley ANBG 


Cartonema spicatum (flowers)
Photo: D.Jones D.Jones 


Commelina cyanea (flowers)
Photo: D.Hardin D.Hardin