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Balsaminaceae


This moderately large family is native to tropical and temperate regions of all continents except Australia and South America. Several species of Impatiens have become naturalised from gardens on the margins of rain forests and wet sclerophyll forests in New South Wales and south-eastern Queensland. Although no species are native to Australia, many occur in the highlands of Papua New Guinea.

Characteristic features of the family Balsaminaceae in Australia include:

  • tender, soft and glabrous annuals or perennials, often with translucent stems without stipules
  • corolla valvate in bud, strongly zygomorphic and bilabiate, or almost actinomorphic, spurred
  • anthers fused to form a cap over the style in young flowers
  • ovary superior, fruits somewhat fleshy, explosive if touched when ripe

Description

Annual, biennial or perennial terrestrial herbs. Extra-floral nectaries absent or on the leaves or phyllodes. Internal secretions not obvious. Stem nodes conspicuously swollen or not; internodes solid, spongy or pithy, terete. Plants glabrous. Leaves alternate and spiral, cauline, petiolate. Stipules absent. Lamina simple, symmetric, ovate to lanceolate; base cuneate or rounded; margins dentate or serrate, flat, revolute or recurved; the midrib conspicuous and the tertiary venation reticulate or not; surfaces not punctate; herbaceous. Domatia absent. Plants with all the flowers bisexual. Inflorescences terminal or axillary, consisting of racemes, spikes, dichasial cymes or solitary flowers. Bracts present. Bracteoles absent. Pollination by insects. Flowers odourless; stalked. Floral disc absent; nectaries absent or on the perianth, the ovary, the stamen filaments or the anthers. Perianth of two dissimilar whorls or with one whorl only, or all whorls ± similar, with 5 or 8 segments, valvate in bud. Calyx irregular; segments free, with 2 or 3 sepals; herbaceous, leathery or membranous; base without appendages or with spurs or pouches. Corolla regular or irregular; segments free or some segments fused, others free, or all fused, with 3 or 5 sepals or lobes, alternating with or with no clear relationship to the sepals; open-tubular, or two-lipped, sometimes with palate, white, orange or pink, without contrasting markings, or streaked, spotted, etc, membranous; claws absent or present; lobes ± entire, notched, emarginate, bifid or bilobed; base without appendages or with spurs or pouches. Fertile stamens 5, irregularly arranged or alternating with the sepals, entirely free or wholly or partly fused with each other or with the corolla or the ovary and style, all ± equal or unequal. Staminodes absent. Anthers basifixed, not versatile, opening inwards by longitudinal slits, 1, 2, 4 or more than 4-celled. Ovary superior. Carpels 5, fused; ovary with 5 locules. Style terminal, single and unbranched, or branched above and the stigma lobed, beaked, 2-lipped, mouth-like or cup-shaped. Ovules more than 10 per locule, sessile or sunken into the placenta; placentation axile. Fruit a dry or fleshy, dehiscent loculicidal capsule with explosive dehiscence; perianth on maturing fruit deciduous. Disseminule micro-surface ± smooth, or tuberculate, colliculate or papillate, white, cream, brown or grey, dull. Seeds per fruit 610 or more. Aril absent. Cotyledons 2. 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 Balsaminaceae has not yet been published in the Flora of Australia. It will appear in Volume 27.

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

* = all species introduced

*Impatiens


Impatiens walleriana (flowers)
Photo: B.Gray CSIRO