The Karrajong Bottle-tree was one of several varieties of Australian trees that were introduced into the Santa Barbara area by our pioneering horticulturists. Many could be seen along city streets by the 1880s. While its numbers seem to have diminished over the intervening years, there are still several mature specimens around town.
It usually grows to become a stout, small- to medium-sized, evergreen tree. However, its shape and size can be incredibly variable, depending on the type of soil and the growing conditions in which it is planted. It can have a narrow pyramidal shape, with a single straight trunk – or a broad-spreading open canopy, with multiple trunks. Though it is quite slow growing, it will eventually attain at height ranging from 20- feet to 50-feet and a canopy width ranging from15- to 40-feet.
While it is in the same genus as other Australian bottle-trees, it rarely has the large wine-bottle-shaped bulge in the middle of the trunk that those develop. Instead, it has a rather expanded trunk near the root crown. When young, the bark is light gray; as it ages, it becomes darker gray. The bark normally has vertical fissures that are shallow – but can also have one or more vertical fissures that are long and deep.
Its shiny green leaves strongly resemble those of poplar trees, an entirely different tree species. The leaves (2- to 3-inches long; 1- to 2-inches wide) are oval-shaped with a pointed apex.
In May through June, this tree produces small (½-inch long and wide) creamy white flowers that hang in panicles (clusters) at the ends of branches. Each flower has five petals; however, the petals are fused together and curve outward at the ends, creating a calyx tube that is bell-shaped. The inside of the tube is spotted with red flecks. The flowers are “perfect”, meaning each has in it both male and female reproductive parts.
After the flowers are pollinated, (1- to 3-inches long), boat-shaped, seed pods form in large numbers. The green- to greenish-brown pods are smooth and leathery on the outside. As they ripen, they dry, turn a dark-brown, and finally split open lengthwise on one suture to reveal rows of orange-brown seeds that resemble kernels of corn. Each pod contains 8 to 12 seeds that are each surrounded by a sheath skirt that is covered with tiny protective hairs. Fair warning: these hairs can be quite irritating to the human skin – precautions should be taken when handling open pods!
Karrajong Bottle-tree is native to eastern Australia, thriving in dry woodlands ranging from central Queensland to southern New South Wales. “Karrajong” is the name given to it by indigenous people living in the foothills of the Blue Mountains of that area.
It is in the Malvaceae (Hibiscus) plant family. Its botanical name is Brachychiton populneus. The genus name, Brachychiton, is formed from the Greek words “brachys”, meaning “short”, and “chiton”, meaning “tunic”; when combined, they refer to the skirt-like shape of the hairy seed coverings. The specific epithet, populneus, means “poplar-like” and refers to the fact that its leaves are similar to those of poplar trees; poplars are in the genus Populus.
Indigenous Australian people had many uses for this tree: the nutritious seeds and tuberous roots of young trees were harvested for food; the fibrous inner bank was processed to make twine for fishing nets and for weaving; the branches were gathered by stockmen as fodder for livestock during droughts; and, the trunk was tapped for emergency drinking water.
Karrajong Bottle-tree is extremely drought-tolerant but requires deep, well-drained soil for consistent lush growth. It should be planted in full sun. It is very adaptable to wetter sites or arid sites – but will grow much larger, if given ample water and annual fertilization in spring. It is cold tolerant to 25 degrees Fahrenheit and free of serious insect or disease pests.
It is easy to propagate from seeds and from cuttings. Seeds will germinate better, if first briefly dipped in hot water and then soaked in warm water for up to 12 hours before planting.
Karrajong Bottle-tree is currently widely planted as an ornamental tree in mild and/or Mediterranean climates around the world. It can be planted as an individual specimen or in multiples, for use as either a street tree, a median tree, a park tree, a tree for open spaces, a tree for commercial landscapes, or a tree for residential gardens.
Examples of mature Karrajong Bottle-Tree can be seen, as street trees, in several places in Santa Barbara: in the 100 to 600 blocks of Alamar Avenue; in the 300 to 400 blocks of Quarantina Street; in the 1500 to 1600 blocks of Castillo Street; in the 500 block of West Pueblo Avenue; and, (not surprisingly) in the Australian Garden of Ganna Walska Lotusland.
Tree-of-the-Month articles are sponsored by Santa Barbara Beautiful, whose many missions include the increase of public awareness and appreciation of Santa Barbara’s many outstanding trees and, in a long-time partnership with the City Parks & Recreation Department, the funding and planting of trees along the City’s streets.
Those who wish to honor a special someone can do so with an attractive commemorative marker that will be installed at the base of an existing street tree in the City of Santa Barbara. Because Santa Barbara Beautiful has participated in the planting to date of over 14,000 street trees, there are plenty of trees from which to choose! Application forms are available on the Santa Barbara Beautiful website, www.sbbeautiful.org.
Article and Photos by David Gress
