Chrysophyllum cainito aka Star Apple

Chrysophyllum cainito, or star apple, belongs to the Sapotaceae family. It is an evergreen fruit tree from the American tropics. Sources place its origin in Central America and the Caribbean. Kew records it as a cultivated plant from Central America. It grows in humid woods at low and middle elevations. People now grow it across many warm regions. It has also spread beyond gardens in several tropical areas.

Garden trees can reach 50–80 feet [15.2–24.4 metres] tall. Their dense crowns may spread just as wide. Other sources report smaller trees and narrower crowns. Useful Tropical Plants gives heights of 13–66 feet [4–20 metres]. It also records trees reaching 115 feet [35 metres]. The crown is round or oval, with drooping branches. The trunk is straight and may flare at its base. Oval leaves have glossy green tops and golden-brown undersides. Fine hairs cover their lower faces.

Small flowers grow in groups where leaves meet the stems. They may look cream, greenish-yellow, or pale purple-white. The flowers have scent but make little visual impact. In Florida, trees flower from August through October. Fruits measure about 0.16–0.33 feet [0.05–0.10 metres] across. Their smooth skins may be green or shades of purple. Soft white flesh surrounds the seeds in separate chambers. A crosswise cut shows the star pattern behind the name. Florida fruit harvests run from February through May.

Full sun supports growth and fruit crops. The tree prefers fertile soil that drains well. It accepts sand and clay where drainage is good. Slightly acid loam suits it, though Florida trees tolerate alkaline soils. Keep soil evenly moist while the tree establishes. Established trees can cope with drought, but harsh dry spells reduce fruiting. They may also shed leaves. Cold winds near 40°F [4°C] can strip foliage. Frost can kill young trees and damage older ones. Missouri Botanical Garden lists zones 10–12 but recommends frost-free zones 11 upward.

Star apple serves as a shade tree and garden specimen. Its leaf colours add interest when branches move. Growers also use its wood, bark tannins, and paper pulp. Seed-grown trees may take five to ten years to fruit. Eat the sweet flesh only when fruit ripens on the tree. Remove the skin and keep its bitter latex away from the flesh. PFAF reports cyanogenic compounds in the seeds. It also records traditional medicinal uses, not proof of benefit. Algal red rust can damage stems and twigs. Fungi affect leaves and fruit, while alkaline soil can cause chlorosis.