Elaeocarpus is a genus consisting of 350 species of tropical and subtropical evergreen shrubs and trees. They are most popular in New Guinea and Bornea, but they also grow in Australia, southern China, and many other countries. Many species of Elaeocarpus may become extinct due to habitat loss. In India, the fruit of these trees are used to make chutney and pickles.
One of the few species that are not threatened, Elaeocarpus reticulatus, is commonly known as blueberry ash. It is native to eastern Australia, but it descended from environments similar to rain forests. While it can still tolerate such environments, it is now capable of thriving in drier conditions. This species has adapted to the new environment in several ways, including hardening its leaves and requiring less water.
Elaeocarpus holopetalus, another rain forest tree that is not threatened, is known by names such as mountain quandong, mountain blueberry, and black olive berry. Its trunk is very smooth and usually dark grey to brown in color. The leaves of this tree are very dark on top, but the leaves closer to the ground are light green. As the tree matures, its leaves turn red permanently. Like most trees in this genus, germination is rare and very slow even when successful.
Rudraksha, or Elaeocarpus ganitrus, is a species that grows on the foothills of the Himalayas and in Hawaii and Indonesia. Though the tree grows quickly, it does not produce fruit until it is four to five years old. The seeds of this tree have been used for Hindu prayer beads for thousands of years. In fact, the tree is mentioned in a well-known Hindu legend in which the Hindu god of all living creatures sheds a tear that grows into the rudraksha tree. This species of the Elaeocarpus genus is also used in traditional Indian medicine to treat some diseases.
Elaeocarpus angustifolius, or the blue marble tree, produces a small blue fruit much like that of other trees in its genus. This fruit is often eaten by birds such as the cassowary, spectacled flying-fox, and wompoo fruit dove. Its seed passes through the birds’ digestive system completely undamaged, allowing the tree to reproduce miles away from its home.
Researchers have concluded that the steady destruction of the genus’ native habitat led to an imbalance between its vegetative and sexual reproduction. After testing fruit from several species, it was discovered that sterile fruit is very common. As of 2010, there is some effort to manage the species by implementing reintroduction programs.