If you have room for a large tree and want to add an exotic specimen to your property, you might consider planting a sausage tree. Native to South and East Africa’s wet savannahs, the tree can eventually grow to more than 30 feet. After about five years, it will start producing long racemes of deep red flowers followed by large sausage-shaped seedpods. The seedpods as well as the flowers make this tree a striking addition to a Hawaiian landscape.
Known botanically as Kigelia africana, the sausage tree is one of about 100 species in the Bignoniaceae family that grow in Hawaiian gardens. Both the better-known jacaranda and gold trees are close relatives that are similar in size and have their own striking characteristics.
The sausage tree has long been cultivated in tropical locales around the world, but it did not arrive in Hawaii until the 1800s. By early 1900, several specimens were growing in parks and on campuses around Oahu. Mature specimens continue to grow and produce their sausage shaped seedpods in Honolulu on the University of Hawaii at Manoa campus as well as in Ala Moana Park. Owing to its unusual features, interested gardeners started successfully propagating sausage trees and they are now growing throughout the Hawaiian Islands. Serving as an outstanding landscape feature, this interesting tree can be found on a few properties here in West Hawaii and is available in the landscape trade. If specimens are not available locally, seeds can be ordered online.
In her native Africa, the sausage tree has many uses. Though the fresh seedpod is not edible, once dried, roasted or fermented it has many culinary, cosmetic and medicinal applications. The seeds aid in beer fermentation and impart a distinct flavor to the local muratina wine. A new Irish vodka is also flavored with sausage tree fruit. Different parts of the sausage tree are used in Africa to treat skin as well as internal ailments.
Because the tree is both drought- and flood-tolerant, it grows close to seasonal African rivers and is often cut and hollowed out to make dugout canoes. It even serves as an African tourist attraction at a luxury safari resort in Zambia named Sausage Tree Camp.
Here in Hawaii, the characteristics of the sausage tree make it an attractive landscape addition. Its drought tolerance makes it a good candidate for dry mid-elevation areas. It is somewhat wind tolerant but not tolerant of salt spray.
The leathery, glossy green leaves of this tree grow into a spreading, dense crown that can offer good shade. Though the leaves are used as fodder in Africa, they are not usually used or consumed here in Hawaii.
The striking, dark red flowers of this tree can be up to 4 inches across and hang below the foliage on long panicles. They open one at a time at night and are often pollinated by bats. The flowers may remain open during the day, however, making a striking display that can attract other pollinators. Though the flowers do offer an aroma, it is not a very pleasant one.
Once the flowers are pollinated, sausage shaped seed pods form and hang on long rope like stems from the tree. The sausages are sometimes more than twelve inches long and can weigh fifteen pounds or more. If left on the tree, they do not drop but wither in place. As the seedpods dry, the seeds can be removed and used to propagate new plants.
The seeds should be sown as soon as they are harvested, since they are only viable for a few weeks. If you need to store them for a few days, do so in a cool dry place. You can hasten germination by soaking the seeds overnight in warm water or by lightly scarifying them with medium grit sandpaper.
Plant the seeds about an inch deep in fast draining soil and water only when the top of the medium dries out. Sausage tree seeds will usually germinate in about three weeks. Once the seedlings are strong, they can be planted out in a full sun location in soil that drains well. Water them every third day until they become established then cut back to deep watering weekly.
Though the fresh sausage shaped seed pods are toxic to humans, many species of African wildlife eat them as well as the leaves. If you get to the San Diego Zoo, you might see elephants, giraffes or monkeys nibbling on pods and leaves of their sausage trees. Here in Kona, you tree will not likely attract such interesting animals, but this tree will certainly offer a unique feature to your landscape.
Diana Duff is a plant adviser, educator and consultant living part time in Kailua-Kona.