Description :

• Trees, dioecious or rarely monoecious, with persistent, at length bark-covered, woody branches from which arise numerous, very slender, ± straight, drooping, little-branched, green and usually flexible, deciduous, Equisetum -like, articulate branchlets, with several short basal articles and 1-many longer, distal articles; articles with as many 4-20 longitudinal ridges
• Leaves on branches and on branchlets reduced to small, dark, triangular scales or teeth connate at base, in a whorl of 4-20 at apex of each article (1 per longitudinal ridge); on persistent branches leaves becoming separate as stem thickens; leaf whorls, and therefore also ribs, alternating at consecutive nodes; stipules 0
• Flowers unisexual, wind-pollinated, very small and much reduced, sessile, solitary in axil of a bract and enclosed by 2 membranous lateral bracteoles, grouped into unisexual inflorescences with closely spaced alternating whorls of bracts similar to scale leaves
• Male inflorescences short to elongated catkin-like spikes, terminating deciduous branches
• Male flowers with a single stamen, enclosed in bud by 1 or 2 (anterior and posterior) concave or hood-shaped membranous perianth segments which break off at base as stamen develops; mature anther exserted, 2-thecous, basifixed
• Female inflorescences shortly stalked or subsessile, ovoid or globular heads, axillary along persistent branches
• Female flower : perianth 0; carpels 2, fused in ovary and in proximal part of style; placentation axile; ovules 2; style 2-branched, reddish, short, with 2 long, filiform, well-exserted stigmas
• Infructescences cone-like, globular, ovoid or cylindrical, ± woody, formed by enlargement and thickening of accrescent bracts and bracteoles of individual flowers, bracteoles usually more elongated and forming pairs of valves enclosing the true fruit and opening when ripe
• Fruit a small samara, very much laterally compressed, apex produced into large, ± translucent wing with 1 longitudinal nerve excurrent at apex
• Seed solitary; endosperm 0; embryo straight, often more than one
• x = 9, 11 (8, 10, 12, 13, 14)

Nomenclature:

• *Casuarina L.
  • Linnaeus: 143 (1759)
  • Adanson: 481, 543 (1763)
  • Forster & Forster: 103, t. 52 (1776)
  • Jussieu: 412 (1789)
  • Miquel: 332 (1868)
  • Engler: 16 (1888) as Casuarinaceae
  • Friis: 499 (1980)
  • Wilmot-Dear: 1 (1985)
  • Wilmot-Dear & Gilbert: 262 (1989)
  • Wilson & Johnson: 100 (1989)
  • Wilmot-Dear: 116 (1991)
  • Johnson & Wilson: 237 (1993)

Distribution & Notes:

• Global : Species 17, tropical to warm-temperate habitats, almost throughout the range of the family except for Tasmania and parts of western and central Australia
• Southern Africa : Species 2, have become partially naturalised in KwaZulu-Natal and Eastern Cape; originally planted for stabilising coastal sands