Pleiogynium timorense

Aboriginal names: Guybalum (Djabugay)

Burdekin Plum, also known as the “Tulip Plum”, is an Australian native that produces plump, acidic fruits that are only edible when very fully ripe. Despite being a rainforest species, it is remarkably hardy and drought tolerant. In the wild it may occur naturally on sand dunes behind mangroves and in dry sub-coastal regions along the northeast coast.

Fruits are large, black, round and contain a large stone. The colour and flavour of the flesh varies between varieties, with red-purple plums being tart, while pale greenish-white plums are more mild. They may be eaten raw, cooked into jams, used to flavour meat, or fermented into wine.

Flowering usually occurs between January and March, producing small, yellowish-green blooms that develop into fruit over the winter months. Harvest the fruits when they start to show signs of ripening, but don’t eat them straight away. They are hard and acidic straight off the tree and need to be stored for a few days. Aboriginal horticulturists were known to bury the fruit underground to assist with the ripening process.

Burdekin Plum prefers a sunny position in loamy, well-drained soil. Though it will tolerate drought (and some frosts), it is best to mulch  and water well during the hot season. It features glossy dark green foliage and a dark grey trunk with rough bark.

In the wild, this tree can reach heights of 20m, but typically grows up to half that height in cultivation. It can be kept smaller in pots, and is sometimes selected as a bonsai species. It is a magnificent tree for a large garden or verge, providing plenty of shade and habitation for birds and small animals.

Burdekin plum features a dark canopy with glossy dark leaves and a rough dark bark. The trees blossoms between January to March. The most common variety appears to have a plum colored flesh however white varieties have been reported. The fruit becomes safe for human consumption only when it is fully ripe. Ripening of the fruit is a process in itself. The fruit is plucked from the tree when it shows signs of ripening, after which the plum is stored in a dark and damp place to complete ripening. (this can take days or weeks). 
In many places, indigenous people buried the fruits underground to provide the right temperature and dampness for the plum to ripen and only returned when they expected the process to be complete.