Tree of the Week: Moreton Bay Fig
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The Moreton Bay Fig -- Ficus macrophylla
The Moreton Bay Fig is famous for its size and notorious for its establishment habits. Huge, century-old specimens grow in Southern California, including in Los Angeles, Santa Barbara and San Diego.
The tree is a strangler fig. To escape dark rain forest floor conditions it usually begins life as a bird deposited epiphytic seed high up on another tree, until its aerial roots reach the ground and become trunks; then it starts to slowly strangle its host. (Here we bypass the host part and plant cutting derived young trees directly in the ground). This ficus is native to tropical Queensland and northern New South Wales on Australia’s eastern coast.
The evergreen Moreton Bay Fig grows to 75 feet tall by 150 feet wide here, but it can reach 200 feet in its native habitat. Aerial roots that change into auxiliary stems when reaching the ground help support the tree’s enormous weight. Buttress and plate roots extend far beyond the tree, but the aggressive yet surficial root system is sensitive to soil compaction. Bark is gray, and varies from rough to smooth. Shiny, leathery, oval leaves -- glossy green above, brownish below -- measure up to 12 by 4 inches.
The species name means ‘large leaves,’ although the leaves are no bigger than those on many other ficus trees. Rose-colored sheaths initially surround leaf buds.
Like all figs, the tree has an obligate mutualism with agaonid fig wasps, meaning that only fig wasps can pollinate the flowers and the fig wasps can only reproduce within figs, where the numerous tiny flowers are borne. Each fig species has its specific pollinator wasp; Pleistodontes froggatti is the tiny pollinator wasp for the MBF, whose inch-long figs are purple spotted with white. The tree loves full sun and regular water, but it is rather drought tolerant. The tree’s size precludes use in all but large gardens and parks.
The Moreton Bay Fig originally was not invasive because without their associated pollinator wasp, ficus trees are unable to reproduce. But the pollinator wasp was deliberately introduced to Maui and Hawaii in 1921 and the tree has become a threat in some areas. This unwelcome wasp has now also arrived in New Zealand.
-- Pieter Severynen
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