1. Casuarinaceae R.Br.

    1. This family is accepted.

[FTEA]

Casuarinaceae, C.M. Wilmot-Dear. Flora of Tropical East Africa. 1985

Habit
Trees or shrubs, monoecious or more often dioecious
Stem
Branches of two kinds: normal, woody branches and deciduous, little-divided green branchlets, thin and usually flexible
Leaves
Leaves on both kinds of branches reduced to whorls of small triangular scales united at base; midribs decurrent to lower node giving a ribbed or grooved appearance to internode; on persistent stems leaves becoming separate as stem thickens; leaf-whorls, and therefore also ribs, alternating at consecutive nodes
Flowers
Flowers grouped into unisexual inflorescences with closely spaced alternating whorls of bracts similar to scale-leaves; male spikes cylindrical, terminating deciduous branches singly, rarely also axillary and shortly stalked on persistent branches; female heads shortly-stalked or subsessile, ovoid or globular, axillary along persistent branches; both male and female flowers sessile and solitary in axil of each bract of whorl; pair of lateral bracteoles enclosing each flower Male flower 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 Female flower without perianth; ovary single; style short, with 2 long filiform well-exserted stigmas
Male
Male flower 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
Female
Female flower without perianth; ovary single; style short, with 2 long filiform well-exserted stigmas
Infructescences
Infructescence cone-like, globular, ovoid or cylindrical, ± woody, formed by enlargement and thickening of accrescent bracts and bracteoles of the individual flowers, the latter usually the more elongated and forming pairs of valves enclosing the true fruit and opening when ripe
Fruits
Fruit a samara, very much laterally compressed, apex produced into large ± translucent wing with 1 longitudinal nerve
[FZ]

Casuarinaceae, C. M. Wilmot-Dear. Flora Zambesiaca 9:6. 1991

Habit
Trees (shrubs), dioecious less often monoecious
Stem
Branches of 2 kinds: normal persistent woody branches and deciduous green branchlets, the latter thin, flexible and little branched
Leaves
Leaves on both kinds of branches reduced to whorls of small triangular scale leaves united at the base (tab. 36, fig. 3), becoming free on the persistent branches; midribs decurrent to the node below giving a ribbed or grooved appearance to the internode; leaf whorls, and therefore also the ribs, alternating at consecutive nodes
Flowers
Flowers grouped into unisexual inflorescences with closely spaced, alternating whorls of bracts similar to the scale leaves Female flower: perianth 0; ovary 1-locular with a short terminal style; stigmas 2, long slender, well-exserted at maturity Male flower: a single stamen enclosed in bud by 1 or 2 (anterior and posterior) concave or cucullate, membranous perianth segments which fall as the stamen develops; mature anther exserted
Inflorescences
Female inflorescence globose or ovoid (tab. 36, fig. 2), shortly stalked or subsessile, axillary toward the ends of woody branches; flowers sessile in the axil of each bract of a whorl; bracteoles as in male flowers Male inflorescence spicate (tab. 36, fig. 2), solitary and terminal on deciduous branchlets (rarely also axillary on woody branches), cylindrical but tapering to a sterile basal region; flowers sessile and solitary in the axil of each bract of a whorl, a pair of lateral scarious bracteoles enclosing each flower
Male
Male flower: a single stamen enclosed in bud by 1 or 2 (anterior and posterior) concave or cucullate, membranous perianth segments which fall as the stamen develops; mature anther exserted Male inflorescence spicate (tab. 36, fig. 2), solitary and terminal on deciduous branchlets (rarely also axillary on woody branches), cylindrical but tapering to a sterile basal region; flowers sessile and solitary in the axil of each bract of a whorl, a pair of lateral scarious bracteoles enclosing each flower
Female
Female flower: perianth 0; ovary 1-locular with a short terminal style; stigmas 2, long slender, well-exserted at maturity Female inflorescence globose or ovoid (tab. 36, fig. 2), shortly stalked or subsessile, axillary toward the ends of woody branches; flowers sessile in the axil of each bract of a whorl; bracteoles as in male flowers
Infructescences
Infructescence cone-like, globular, ovoid or cylindrical; ± woody due to the enlargement and thickening of accrescent bracts and bracteoles of individual flowers, the latter much the larger (often with a dorsal protuberance) and forming pairs of valves enclosing the true fruit and opening when ripe
Fruits
Fruit a dark brown to black and shiny or pale grey-fawn and rather dull samara, laterally compressed, bearing a large ± translucent wing with a single longitudinal nerve excurrent at the apex
[NTK]

Every, J.L.R. (2010). Neotropical Casuarinaceae.

Morphology
Description

Evergreen trees and shrubs, slender, with wiry, jointed and grooved branches with quadrangular segments. Leaves reduced into simple , sessile scales grouped in whorls of 4-20, these surrounding the articulations, indumentum of simple or branched trichomes, plants rarely glabrous . Inflorescences indeterminate, catkins, (male flowers terminal , female flowers in a globose heads on side branches). Flowers unisexual (plants monoecious or dioecious ), reduced, radially symmetrical, bracteate and with 2 bracteoles, tepals inconspicuous. Staminate flowers grouped together along the spike , stamen 1, free of perianth , anthers basifixed, dehiscing by longitudinal valves. Pistillate flowers naked, ovary superior , syncarpous, carpels 2, bilocular , styles 1-2, short. Fruits of adjoining bracteoles and perianth forming a multiple cone-like infructescence of samaroid nuts. Seeds 1.

Distribution
Distribution in the Neotropics
  • Introduced and naturalised throughout the Neotropics.
Diagnostic
Distinguishing characters (always present)
  • Highly reduced scale-like leaves.
  • One stamen.
  • Multiple infructescence formed by enlarged and thickened bracteoles and perianth.
  • Fruit black and shiny with slightly raised wavy lines.
Key differences from similar families
  • Superficially and vegetatively Casuarianaceae resemble gymnosperms or Equisetum L., but the Angiosperm flowers set them apart.
General Description
Number of genera
  • One genus: Casuarina L.
  • Two species: Casuarina equisetifolia L. and C. cunninghamiana Miq.
General notes
  • Nitrogen-fixing roots.
  • Commonly known as the She-Oak Family and Beefwoods.
  • A global noxious weed.
  • Wind pollinated and dispersed, but an important source of firewood and construction materials for some communities.
Status
  • Naturalised.
Notes on delimitation
  • Placed in the Fagales, sister to Betulaceae and Myricaceae (APG III, 2009).
Literature
Important literature

APG III. 2009. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants. Bot. J. Linn. Soc. 161(3): 105-121.

Jury, S.L. 2007. Casuarinaceae, pp. 91-92. In: Heywood, V.H., R.K. Brummitt, A. Culham and O. Seberg (eds.). Flowering Plant Families of the World. Royal Botanic Gardens, Kew.

Judd, W.S., Campbell, C.S., Kellogg, E.A., Stevens, P.F. and Donoghue, M.J. 2008. Plant Systematics: a phylogenetic approach 3rd ed. Sinauer Associates, Massachusetts. Pp 387-389.

Johnson, L.A.S. and Wilson, K.L. 1993. Casuarinaceae, pp. 237-242. In: Kubitzki, K (ed.). The Families and Genera of Vascular Plants. Vol II. Springer-Verlag, Berlin.

Stevens, P. F. 2008. Angiosperm Phylogeny Website. Version 9 onwards. http://www.mobot.org/MOBOT/research/APweb/

Watson, L. and Dallwitz, M.J. 1992 onwards. The Families of Flowering Plants: Descriptions, Illustrations, Identification, and Information Retrieval. Version 3rd March 2009. http://delta-intkey.com

Wilmot-Dear, C. M.1991. Flora Zambesica, vol 9: part 6, p. 116., Royal Botanic Gardens, Kew.

Images

Casuarinaceae R.Br. appears in other Kew resources:

First published in Voy. Terra Austral. 2: 571. 1814 [19 Jul 1814] (1814)

Accepted by

  • APG IV (2016) http://dx.doi.org/10.1111/boj.12385

Sources

Flora Zambesiaca
Flora Zambesiaca
http://creativecommons.org/licenses/by-nc-sa/3.0

Flora of Tropical East Africa
Flora of Tropical East Africa
http://creativecommons.org/licenses/by-nc-sa/3.0

Kew Names and Taxonomic Backbone
The International Plant Names Index and World Checklist of Selected Plant Families 2019. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
© Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

Neotropikey
Milliken, W., Klitgard, B. and Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics.
http://creativecommons.org/licenses/by/3.0