Inflorescences: Male and female on the same plant (monoecious). Male—grouped in simple, terminal whorls forming short cylindrical spikes 0.7-4 cm long. Female— borne on lateral woody branches, forming a globose cone, 1-2.4 X 0.9-1.3 cm, on a short stalk, 0.1-1.3 cm long, often among the foliage; cone bracteoles acute, more or less protruding from the surface of the cone; sparsely hairy (equisetifolia) or covered in fine, white or rusty hairs (incana). Flowers Aug.-Sept. (equisetifolia), Sept.-Oct. (incana).
Fruits: Dull brown samaras, ovate, 0.6-0.8 cm long, slightly flattened with a short, barely transparent terminal wing having a prominent middle vein, enclosed by the woody bracteoles of the cone. Mature Nov.-Feb. (equisetifolia), Mar.-Apr. (incana).
Wood: Sapwood is not susceptible to Lyctus attack; heartwood is very hard and very heavy, lacks the prominent rays characteristic of other casuarinas, density 960 kg m-3, strong and durable in the ground or submerged in saltwater; an excellent firewood burning satisfactorily when green and produces an exceptionally fine charcoal. Uses throughout its range include fishing boat masts, piles, posts, roof shingles, tool handles and paper pulp (cultivated stands).
Climate: Altitudinal range: near sea level to 100 m; Hottest/ coldest month: 30-35°C/6-20°C; Frost incidence: nil to low; Rainfall: 950-2100 mm per year, summer max.
Distinctive features: A casuarina occurring along coastal foreshores, normally in pure stands, with a crown that comprises drooping, needle-like foliage; male and female flowers are monoecious; fruits are woody cones that have rows of numerous bracteoles; phyllichnia have 7-8 leaf teeth per node. This species is planted in many countries for many purposes including shelterbelts and land rehabilitation of sandy sites.
Casuarina equisetifolia 1. Bark on maturing tree 2. Seeds 3. Female flowers 4. Male flowers 5. Bark on mature tree 6. Dehisced cones 7. Seedling 8. Tree, Percy Island, Qld (subsp. incana) 9. Tree, Wah Wee Beach, N.T. (subsp. equisetifolia) 10. Flowering sprig 11. Sprig with mature cones
Swamp Oak Swamp Sheoak
Swamp oak is usually a medium-sized tree up to 20 m tall and with stem diameters to 0.75 m, with older trees being slightly buttressed at their bases and the trunks occasionally fluted. The species is very conspicuous in coastal situations and is often found just behind the mangrove fringe. Crowns and stems are often slender where the species grows in dense, pure stands. It typically has a poorly developed taproot and a well-developed lateral root system. The foliage is greyish, has long pendulous stiff branchlets, which are noticeably of uneven length. The species is able to sucker vigorously from its roots.
This species occurs near the sea between Bermagui in south coastal New South Wales through to north of Gladstone, Queensland, with an insular occurrence on Fraser Island. In only two regions does it extend far inland, and these are in the Sydney region (about 50 km inland) and the Singleton area (about 80 km inland).
Swamp oak occurs on flat, swampy sites or in close proximity to salty or brackish water. The species grows on river banks and beside streams affected by tidal influence and commonly forms belts 5-50 m wide. Swamp oak occurs on dark, alluvial soils that have a high organic content. The soils are usually fairly acidic but saline and with various mineral nutrients in good supply. The watertable is usually within 1 m of the surface.
The species typically forms pure stands in open forests and woodlands and, while it usually grows on drier ground fringing grey mangrove (Avicennia marina) and Melaleuca species (chiefly M. quinquenervia) swamps, it may on occasion be found growing in admixture with the latter. Other species found nearby include forest red gum (Eucalyptus tereticornis) and occasionally species of the littoral rainforest such as red ash (Alphitonia excelsa) and tuckeroo (Cupaniopsis anacardioides). Some unusual stands are the small shrub-like communities, that are often burnt, on exposed coastal headlands, and in these situations common associates include coast bank-sia (B. integrifolia).
Related species: Swamp oak is closely related to the Western Australian swamp oak (C. obesa). Slight differences distinguish the two: in C. obesa the teeth on young shoots are appressed or slightly spreading while in C. glauca the teeth are longer and recurved. C. obesa occurs mainly in the Murchison, northern wheat belt and goldfields regions of Western Australia, with widely disjunct outliers in the Wimmera region of Victoria.
Publication: Syst. Veg. 3, 803 (1826). Type: New South Wales, F.W. Sieber 325.
Names: Botanical—Latin glaucus (bluish grey or bluish green), in reference to the colour of the leaves rather than to the possession of a waxy covering. Common—refers to its usual habitats, the term oak being explained under C. cunninghamiana.
Bark: Greyish to light black, rough, hard, persistent; shallowly longitudinally furrowed with even shallower cross-furrows to give a tessellated appearance (1-2 cm squares). Some trees close to rivers are covered in masses of grey lichens.
Leaves: Cotyledons—sessile or slightly joined at base, elliptical, 0.2-0.3 X 0.1-1.5 cm; reddish hypocotyl covered in stubby hairs. Seedling—deciduous and permanent branches similar in morphology, whorls of 4 leaf teeth at the joints, the number gradually increasing at subsequent nodes, internodes (articles) 0.3-0.5 cm long. Adult—deciduous and permanent branches noticeably different in morphology, deciduous branchlets of uneven length, up to 30 cm long, shed after 2-3 seasons, thickish (about 0.1 cm diameter), leaf teeth in whorls of 12-16, internodes (articles) 0.8-1.5 cm long.
Inflorescences: Male and female flowers on separate trees. Male—grouped in whorls forming dense spikes 2-4 cm long and 0.2-0.3 cm wide at the ends of deciduous branchlets; flowers usually Sept.-Oct. Female—grouped in alternating whorls of 12-16, eventually forming a greyish subglobose to shortly cylindrical cone, 1-2 X 1-1.5 cm on a stalk about 0.4-1 cm long; fruiting cones often pubescent and bracteoles thin.
Fruits: Samaras are dull yellowish brown with some black streaks, ovate, slightly flattish, up to 0.4 X 0.2 cm, winged with brown middle and marginal vein.
Wood: Sapwood narrow, pale, not susceptible to Lyctus attack; heartwood brownish and has conspicuous rays, hard, tough and fissile, very dense, density 980 kg m-3. The species is used for handles, fencing rails, shingles, stakes, small piles in seawater and for flooring and turnery. It is an excellent fuel and is very suitable as an ornamental and for windbreaks in coastal locations.
Climate: Altitudinal range: near sea level to 90 m; Hottest/ coldest month: 27-30°C/4-11°C; Frost incidence: low; Rainfall: 900-1100 mm per year, mainly summer max.
Distinctive features: Typically an estuarine Casuarina, with long, thick deciduous branchlets. Cones have rather thin bracteoles without markings or protuberances on their backs. Samaras are pale. The species regenerates vigorously from root suckers.
Casuarina glauca 1. Stand, Nambucca Heads, N.S.W. 2. Cones before dehiscence 3. Branchlets 4. Male inflorescences 5. Cones after dehiscence 6. Leaf teeth at joint (S.E.M.) 7. Male inflorescence, upper section, before emergence of anthers (S.E.M.) 8. Tree, near Coopernook, N.S.W. 9. Bark 10. Seedling
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