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Rhizophoraceae


This small family is pantropical but with few representatives in the New World. The five genera in Australia are all trees or shrubs, of mangrove forests fringing estuaries, or rain forests along freshwater creeks in tropical areas, extending south as far as Dampier, WA, and the north coast of NSW.

Characteristic features of the family Rhizophoraceae in Australia include:

  • trees or shrubs, often with buttressed trunks or stilt roots, and pneumatophores (aerial breathing roots)
  • leaves opposite, often large and leathery, entire
  • flowers with prominent, leathery sepals numbering up to 16 and smaller, often divided or clawed petals
  • fruits indehiscent and leathery or fleshy, in the mangrove species the seed often germinates before the fruit is shed (vivipary)

Description

Evergreen trees or shrubs. Internal secretions not obvious. Plants glabrous. Leaves opposite, petiolate. Stipules interpetiolar, scale-like or membranous, falling off early. Lamina simple, symmetric, lanceolate, ovate, oblanceolate, obovate or oblong; base cuneate or attenuate; margins entire, ±flat; venation pinnate, with the midrib conspicuous, and the tertiary venation not reticulate; surfaces punctate or not punctate; leathery. All the flowers bisexual. Inflorescences axillary, consisting of dichasial cymes or solitary flowers. Bracts absent. Bracteoles present. Pollination by insects or birds. Flowers odourless, sessile or stalked. Floral disc present; nectaries absent. Free hypanthium absent or ±present. Perianth regular, of 2 dissimilar whorls, valvate in bud. Calyx segments free or fused, with 416 sepals or lobes; calyx bell-shaped, herbaceous or succulent. Corolla segments free, with 416 petals, alternating with the sepals or calyx lobes, free, white, cream or yellow, without contrasting markings, membranous; claws present or absent; lobes ±entire, or notched, emarginate, bifid, bilobed, ciliate or fimbriate. Fertile stamens 8 or numerous, not clearly correlated with the sepals or calyx lobes, free of the corolla, free of ovary and style, distinct from each other, all ±equal. Staminal filaments present or absent. Anthers basifixed, not versatile, opening inwards by longitudinal slits, 4-celled or more than 4-celled. Ovary part-inferior or inferior. Carpels 28, fused; ovary with 28 locules. Style terminal, single and unbranched with the stigma lobed. Ovules 2 per locule, stalked; placentation apical. Fruit a fleshy indehiscent berry; the perianth on the maturing fruit deciduous, or dry and persistent, or growing larger. Disseminule micro-surface ±smooth, red, pink or green, glossy or not. Seeds 14 per fruit. 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 Rhizophoraceae has been published in:
Flora of Australia 22: 1-10.

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

Bruguiera
Carallia
Ceriops
Gynotroches
Rhizophora


Bruguiera gymnorhiza (fruits)
Photo: A.Lyne ANBG 


Bruguiera gymnorhiza (fruits)
Photo: A.Lyne ANBG 


Bruguiera gymnorhiza (habit)
Photo: A.Lyne ANBG 


Carallia brachiata (flowers)
Photo: D.Jones D.Jones