Nyctaginaceae

Most members of this tropical family are found in Central and South America; a few native species and a few introduced species occur in Australia, mostly on the margins of near-coastal rainforest. Boerhavia, by contrast, is widely distributed throughout much of Australia except the far west, including arid regions.

Characteristic features of the family Nyctaginaceae in Australia include:

• prostrate or erect herbs, shrubs or woody scrambling shrubs or small trees, sometimes with stout thorns
  
• leaves usually opposite, simple
  
• flowers with a single whorl of perianth parts fused into a cup or tube, sometimes with several flowers surrounded by brightly coloured bracts
  
• fruits ribbed, ellipsoid, indehiscent, often sticky-glandular

Description

Evergreen trees, or shrubs, or woody or herbaceous scrambling vines, or annual or perennial terrestrial herbs. Perennating by tubers or taproots. Stems unarmed or rarely with thorns arising from leaf axils. Internal secretions not obvious. Plants glabrous or with simple, glandular or non-glandular, uniseriate hairs. Leaves alternate and spiral, or opposite, or whorled, cauline or both basal and cauline if herbs, petiolate, subsessile or sessile. Stipules absent. Lamina simple, symmetric, filiform, acicular, subulate, linear, lanceolate, ovate, elliptic or oblong; base cuneate, attenuate or rounded; margins entire, ±flat; venation pinnate, with the midrib conspicuous, and the tertiary venation reticulate or not; surfaces not punctate; herbaceous. Domatia rarely present. Male and female flowers occurring on the same plant, or on separate plants, or with all the flowers bisexual. Inflorescences terminal or axillary, consisting of capitula, glomerules, cymes, umbels or solitary flowers. Bracts present, sometimes large and bright pink, or absent. Flowers odourless or fragrant, sessile or stalked. Perianth regular, of 1 whorl only, with 5–10 fused petaloid segments, or rarely with a distinct "calyx and corolla" (by misinterpretation), valvate in bud, bell-shaped or funnel-shaped, white, cream, yellow, red, pink, magenta or purple, without contrasting markings, or streaked, spotted, etc, membranous; lobes ±entire. Fertile stamens 1–30, alternating with or not clearly correlated to and free of the perianth segments, free of the ovary and style, distinct from each other or fused by their filaments into an open or closed tube, all ±equal or markedly unequal. Anthers dorsifixed, ?versatile or not versatile, opening sideways by longitudinal slits, 2-celled. Ovary superior and sessile. Carpel 1; ovary with 1 locule. Style terminal, single and unbranched. Ovule 1, sessile; placentation basal. Fruit a dry indehiscent achene; the perianth on the maturing fruit deciduous or dry and persistent. Disseminule macro-surface costate; micro-surface ±spinulose, papillate, tuberculate or verrucose, green, brown, grey or black, dull. Seeds 1 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 Nyctaginaceae has been published in:
Flora of Australia 4: 5-18.

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

* = all species introduced

Boerhavia
*Bougainvillea
*Mirabilis

Pisonia umbellifera (fruits)
Photo: J.Plaza © J.Plaza