Casuarina equisetifolia aka Beach Sheoak

Casuarina equisetifolia stays green all year. It belongs to the Casuarinaceae family. People call it Australian pine, coast she-oak, and horsetail tree. It is a broadleaf tree, not a true pine. Its native range runs from India to the western Pacific. It includes Southeast Asia, Australia, and many Pacific islands. The tree grows on sandy shores and dunes. It also grows by estuaries, where rivers meet the sea. It seldom grows far inland but reaches low coastal hills.

The tree grows fast and has a straight trunk. Garden sources give heights near 98 feet [30 metres]. One source gives a spread of 66 feet [20 metres]. Other sources give heights up to 148 feet [45 metres]. Rare trees reach 197 feet [60 metres]. The crown may have a vase shape or grow broad and flat. Thin green branchlets hang from the limbs. They make food from light through photosynthesis. Tiny leaves look like scales and ring the branchlet joints. Young bark is smooth. With age, it splits into grey or reddish-brown strips.

Small male flowers form narrow spikes at the branch tips. Female flowers form small groups near the branchlet bases. Oregon State says one tree bears both sexes. Wind carries the pollen. Yet sources say the tree is not self-fertile. The woody fruit looks like a small cone. It turns reddish brown and has many pointed scales. The thin branchlets and cone-like fruit make it look like a pine.

Full sun suits this tree; PFAF also lists light shade. It grows in sand, loam, or clay that drains well. It accepts poor soil, from slightly acid to neutral. Root bacteria help it get nitrogen from the air. It copes with drought and needs little to regular watering. Sources place it in USDA zones 9–12. Oregon State says it copes well with salt. That source also notes that people often plant it on beaches. PFAF gives mixed guidance on direct exposure to the sea. Growers use it to block wind, make screens, and stop erosion. Its wood makes posts, poles, and tool handles. People also use the wood for fuel and charcoal.

This tree can spread beyond planted sites and become invasive. Oregon State notes its serious impact in south Florida. Seedlings can suffer damping-off. Ants can also affect seed sowing. PFAF warns of sharp plant parts. Useful Tropical Plants lists no known hazards. Neither source proves the plant is safe from toxic effects. PFAF records that people roast seeds for salt. It also notes chewing leaves and green fruit to ease thirst. Folk remedies use roots for gut complaints and twigs for swelling. They also use bark for pimples. These reports describe uses, not proven treatments.