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Elatinaceae


Members of this small, cosmopolitan family are waterplants or grow in seasonally wet or damp areas. They are found almost throughout Australia in open areas, but are not often seen.

Characteristic features of the family Elatinaceae in Australia include:

  • annual or perennial herbs (occasionally somewhat shrubby, or submerged aquatics), with opposite or whorled leaves and green and leafy or fringed stipules
  • flowers small, regular, bisexual, in axillary clusters or solitary, with 3-5 free sepals and petals
  • ovary superior, developing into a capsule with numerous small seeds with finely sculptured seed coats

Description

Evergreen shrubs, annual or perennial terrestrial herbs, or aquatic herbs rooted in the substrate with their leaves all or mostly submerged. Perennation by taproots. Vegetative reproduction absent or by stolons. Internal secretions not obvious. Plants glabrous or with simple, glandular or non-glandular, uniseriate or multiseriate hairs. Leaves opposite, cauline if herbs, petiolate, subsessile or sessile. Stipules distinct and free from the petiole, green and leaflike, or lacerate, or fimbriate, persistent. Lamina simple, symmetric, elliptic, oblanceolate, obovate or orbicular; base cuneate; margins entire or serrate, ±flat; venation pinnate, with the midrib inconspicuous, and the tertiary venation not reticulate; surfaces not punctate; herbaceous. All the flowers bisexual. Inflorescences axillary, consisting of dichasial cymes, verticillasters or solitary flowers, or rarely glomerules. Bracts present or absent. Bracteoles present. Flowers odourless, stalked or rarely sessile. Perianth regular, of 2 dissimilar whorls, imbricate in bud. Calyx segments free, with 35 sepals, herbaceous, rarely auriculate. Corolla segments free, with 35 petals, alternating with the sepals, white or pink, without contrasting markings, membranous; claws absent; lobes ±entire. Fertile stamens 35 or 10, both opposite to and alternating with the sepals, free of the corolla, free of the ovary and style, distinct from each other, all ±equal. Anthers dorsifixed, versatile, opening inwards by longitudinal slits, 2-celled. Ovary superior and sessile. Carpels 35, fused; ovary with 35 locules. Style terminal, branching from the base. Ovules numerous per locule, sessile; placentation axile. Fruit a dry septifragal or septicidal capsule; the perianth on the maturing fruit rotting or liquefying, or dry and persistent. Disseminule micro-surface ±smooth or alveolate, orange or brown, glossy or dull. Seeds numerous per fruit. Aril absent. Cotyledons 2. Embryo straight or curved.
(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 Elatinaceae has not yet been published in the Flora of Australia. It will appear in Volume 6.

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

Bergia
Elatine


Bergia henshallii (flowering branch)
Photo: B.Fuhrer B.Fuhrer