Description: Trees, dioecious (except for C. equisetifolia). Bark fissured or scaly, grey-brown to black.
Teeth 6–20 per whorl.
Cones borne on short peduncle, white- or rusty-pubescent at least when immature, often becoming glabrous with age; bracteoles extending well beyond the cone body, never greatly thickened and always lacking a dorsal protuberance. Body of mature samara pale yellow-brown or greyish, dull, glabrous.
Distribution and occurrence: World: 17 species, range more or less as for family. Australia: 6 species, all mainland States.
Not usually found on soils greatly deficient in nutrients (cf. Allocasuarina). See notes under family description about the differences between fresh and dried material, especially when using the key.
Text by K. L. Wilson & L. A. S. Johnson (1990); edited KL Wilson (Feb 2014, Feb 2017)
Taxon concept:
| | Key to the species | |
| 1 | Ridges narrow, prominently angular, occasionally flat in Casuarina equisetifolia but then densely hairy on ridges as well as in furrows; teeth 6–10, withering or not withering | 2 |
| Ridges wide, flat or slightly rounded-convex or with a median groove; teeth 8–20, mostly withering | 3 |
| 2 | Branchlets and cones more or less densely and obviously hairy; teeth 6–8, not withering; cone body 10–20 mm long, 10–13 mm diam., with acute bracteoles; samara 6–8 mm long | Casuarina equisetifolia |
| Branchlets and cones sparsely and minutely hairy; teeth 8–10, withering; cone body 7–14 mm long, 4–6 mm diam., with broad-acute bracteoles; samara 3–4 mm long
Back to 1 | Casuarina cunninghamiana |
| 3 | Teeth 12–20; ridges smooth, flat or slightly rounded-convex; cones 7–10 mm diam. with thin, broad-acute bracteoles 2.0–2.5 mm wide and with only 1 obvious striation; samara 3.5–5.0 mm long | 4 |
| Teeth 8–13; ridges minutely roughened, flat or with a median yellowish groove (often masked by wax); cone body 10–16 mm diam. with thick acute bracteoles 3.5–4.0 mm wide and with several obvious striations; samara 5.5–10.5 mm long
Back to 1 | 5 |
| 4 | Teeth on young permanent shoots long-recurved | Casuarina glauca |
| Teeth on young permanent shoots appressed or slightly spreading
Back to 3 | Casuarina obesa |
| 5 | Teeth erect, appressed, 8–12, 0.5–0.7 mm long; articles 0.6–0.9 mm diam., somewhat waxy, occasionally sparsely hairy; teeth on new shoots erect to somewhat spreading | Casuarina cristata |
| Teeth spreading to recurved, 9–13, 0.8–0.9 mm long; articles 1.0–1.8 mm diam., strongly waxy, densely and very shortly hairy; teeth on new shoots spreading
Back to 3 | Casuarina pauper |
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