Nature
Australian pine (Casuarina equisetifolia) is a fast-growing tree, and is planted widely for wood production, erosion control, and production of timber, tannin, dye, and pulp (1). The height of the tree usually varies between 8–35 m. (2). The bark of the tree is light-gray brown; the younger trees have smooth bark while older trees have rough and deeply furrowed bark (3). The tree crown is slender, finely branched, furrowed with greyish green branchlets (15–38 cm long and <1.0–1.5 mm in diameter). They have 7-8 dentate concentric circles (whorls) per node. Usually, male and female tress are separate. However, in some areas monoecious trees (male and female flowers on same tree) are also found. The spike inflorescence is observed in these trees with male inflorescences as simple, 7-40 mm long and elongated spikes and bears 7–11.5 whorls per cm of a spike. Female inflorescences are cone-shaped, 5–10 mm long and ellipsoid (2). Casuarina species are wind pollinated. The pollination occurs from February through May in the Northern Hemisphere (4).
Habitat
Australian pine trees are commonly found on sand dunes, estuaries behind foredunes, the leading edge of dune vegetation, and gentle slopes near the sea. This tree can be seen along thin belts near to sandy coastlines and up to an altitude of 100 m above sea level. They appear as crooked low-branching trees on exposed seashores and grow as straight-stemmed forests tree in sheltered areas. Well-drained, coarse textured, sands of 2 m or more in-depth soil type is usually preferred by this tree. It tolerates calcareous and slightly alkaline soils, and intolerant to waterlogging. (2). This tree is draught tolerant and can sustain without water for around 6 – 8 months (3).
Taxonomy
Australian pine belonged to the genus Casuarina. This genus comprises about 14 species; of which 10 species were introduced outside their native territory. Only three species (C. equisetifolia, C. cunninghamiana, and C. glauca) are considered as naturalized or invasive. Species belonging to the genus Casuarina are usually called casuarians (such as Australian pine, beefwoods, she-oaks, etc.) (5).
| Taxonomic tree of Australian pine (6) |
|---|
| Domain |
Eukaryota |
| Kingdom |
Plantae |
| Phylum |
Spermatophyta |
| Subphylum |
Angiospermae |
| Class |
Dicotyledonae |
| Order |
Fagales |
| Family |
Casuarinaceae |
| Genus |
Casuarina |
| Species |
Casuarina equisetifolia |
| Taxonomic tree of Australian pine (6) |
|---|
Tissue
Australian pine pollen grains are medium sized from 25.25 x 27.82 μm. Its shape varies from oblate to spheroidal. They are having 3 or 4 apertures which are regularly spaced around the edge. The exine of the pollen grain is completely smooth (7).
