Gunneraceae

This is a small, Southern Hemisphere family most diverse in tropical and temperate South America and in New Zealand, with a few species in South Africa, Malesia and Australia. Only one species (Gunnera cordifolia) occurs in Australia. It is confined to upland bogs in northern Tasmania.

Characteristic features of the family Gunneraceae in Australia include:

• small, perennial, stoloniferous herb often forming extensive mats, with alternate leaves
  
• flowers inconspicuous, unisexual, the male and female flowers usually in separate inflorescences on the same plant, the males in interrupted spikes, the female inflorescences more head-like
  
• stamens 1-2
  
• ovary inferior; fruit a globular to oval, bright red drupe

Description

Perennial terrestrial herbs. Perennating by rhizomes. Vegetative reproduction by stolons. Internal secretions not obvious. Plants glabrous or with simple, non-glandular, uniseriate hairs. Leaves alternate and spiral; all or mostly basal, petiolate. Stipules absent. Lamina simple, symmetric, dorsiventral; lanceolate, ovate or oblong; base rounded or cordate; margins serrate, revolute or recurved; venation pinnate, with the midrib conspicuous, and the tertiary venation not reticulate; surfaces not punctate; herbaceous or succulent. Male and female flowers occurring on the same plant or on separate plants, or very rarely flowers bisexual. Inflorescences axillary, consisting of capitula (female) or spikes (male). Bracts present or absent. Bracteoles present. Pollination by wind. Flowers odourless; sessile. Floral disc absent; nectaries absent. Perianth regular, of 2 dissimilar whorls with 4 segments, open in bud. Calyx segments free, with 2 sepals; herbaceous. Corolla segments free, with 2 petals, alternating with the sepals, free, 1-lipped; green; without contrasting markings; membranous; claws absent; lobes ±entire. Male flowers with sepals, petals and ovary absent, fertile stamens 1–2, distinct from each other, all ±equal; anthers basifixed, not versatile, opening ?sideways by longitudinal slits, 4-celled; with apical appendages. Female flowers with 2 (often minute) sepals, 2 ± hooded petals, no stamens. Ovary inferior. Carpels 2, fused; ovary with 1 locule. Style single and unbranched or branching from the base, terminal. Ovules 1, stalked; placentation apical. Fruit a dry indehiscent nut or a fleshy drupe; the perianth on the maturing fruit dry and persistent. Disseminule micro-surface ±smooth, red, glossy. Seeds 1 per fruit. Aril absent. Cotyledons 2. Embryo round or shapeless.
(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 Gunneraceae has been published in:
Flora of Australia 18: 85-87.

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

Gunnera