Coolibah Trees. Eucalyptus microtheca Myrtle Family ( Myrtaceae ), Coolibah. Also Called: Blue Coolibah, Eucalyptus coolabah, Flooded Box, Tiny Capsule Eucalyptus, Old Gum Tree. We wish to thank Wikipedia, the free encyclopedia for some of the information on this page. We share images and information with Wikipedia. Coolibah is an evergreen tree 18 - 60 feet high, usually crooked or irregular. Said to be the most widely planted non-native evergreen tree in Arizona. Coolibah branches are less susceptible to be broken by the wind than other Eucalyptus trees, therefore it is a good choice for Arizona. Quick Notes: Height: Up to about 18 - 60 feet. About a 20 - 30 foot spread. Fast Growing. Trunk: The trunk is 2 - 3 1/2 feet in diameter. Bark: An attractive rough trunk; creamy, flaky with a few rough patches of loose brown bark. Flowers: The flowers are on slender stalks ending in umbels of 3 � 7 white, short stalked fragrant flowers. Flowers are very small, the bud is 4 � 6 mm long. With many stamens, spreading, white, short, 3 � 4 mm long, anthers rounded with a small round gland. Pistil with inferior a 3 � 4-celled ovary and stout style. Blooming Time: Mid July to November. Seed Pods: Woody and massive capsules (4 to 5 cm diameter), bell-shaped, and strongly ridged, and the depressed center of the fruit is glossy red. The dried stamens often persist on the maturing fruits, and fruits eventually open at the top by way of four splits. Seeds: Dark brown seeds which germinate readily. Leaves: Leaves alternate, narrowly lanceolate, 2 1/4 to 7 3/4 inches long, 3/8 inch to 1 1/8 inch wide, acuminate apically, basally acute, not entire, glabrous, slightly thick, leathery, dull green, slightly paler underneath. Found: Native to Western Australia, in the Northern Territory, Specifically, The Kimberley. Elevation: Native at 0 - 2,200 feet. Hardiness: We have read reports of the tree dying at lows of 16 �F USDA Zone 8b: to -9.4 �C (15 �F) USDA Zone 9a: to -6.6 �C (20 �F) USDA Zone 9b: to -3.8 �C (25 �F) USDA Zone 10a: to -1.1 �C (30 �F) USDA Zone 10b: to 1.7 �C (35 �F) USDA Zone 11: above 4.5 �C (40 �F) Soil pH requirements: 5.6 to 6.0 (acidic) 6.1 to 6.5 (mildly acidic) 6.6 to 7.5 (neutral) 7.6 to 7.8 (mildly alkaline) 7.9 to 8.5 (alkaline) 8.6 to 9.0 (strongly alkaline) Sun Exposure: Full Sun Habitat: In native Australia, it commonly grows on limestone soils it is well adapted to alkaline conditions. Miscellaneous: Photos Taken: September 11, 2006. Glendale, Arizona. Considered a Xeriscape Landscaping plant.

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