Sausage Tree (Kigelia africana): Evergreen Tree Appearance, Fruit Edibility, and Seed Extraction Methods

The sausage tree, a plant in the genus Kigelia of the family Bignoniaceae, blooms in spring and summer, originates from Africa, and prefers light and warmth. It can be used as a landscape tree or as a street tree. So, what does the "evergreen tree" sausage tree look like? Is its fruit edible? How do you extract the seeds?

1. What does the "evergreen tree" sausage tree look like?

The sausage tree grows 10-15 m tall, with a clear trunk height of about 2 m and a diameter at breast height of about 1 m. The odd-pinnate compound leaves are alternately opposite or whorled, with a rachis 7.5-15 cm long; there are 7-9 leaflets, oblong or obovate, with acute tips and wedge-shaped bases, entire margins, smooth bright green upper surfaces, and pale green undersides covered with fine pubescence, nearly leathery, with obvious pinnate veins. The panicles grow at the tips of the branchlets, with drooping inflorescence axes 50-100 cm long; the flowers are sparse, 6-10 per inflorescence.

2. Is its fruit edible?

The fruit of the sausage tree is candle-shaped, with a woody outer skin, and does not split open. The fruit is large, weighing up to 1.5-3 kg, hanging from the branches and not falling for a long time, hence the name "sausage." The fruiting period is long, and the fruit can be viewed from October to February-March of the following year. A single large, high-yielding tree can produce 80-150 fresh fruits per year. Unfortunately, the fruit has extremely abundant woody fiber and cannot be eaten.

3. How do you extract seeds from the sausage tree?

The sausage tree can be propagated by sowing, cuttings, and layering. When sowing, the mature fruits collected from October to November are generally cracked open, the seeds are taken out and dried, and then sown in March to April of the following year. Before sowing, the seeds can be soaked to promote germination, and after germination treatment they usually sprout in 10-15 days. However, because the fruit is hard and the flesh is highly fibrous, it is rather difficult to extract the seeds directly by hand. They can be soaked in water to let them rot naturally and then be taken out; after being dried slightly, they can be sown directly. The seedlings can be planted out after 2-3 years.

Cuttings of the sausage tree are best taken from April to May during the peak growth season. Generally, softwood cuttings from 1-2-year-old growth have a higher survival rate.

For layering propagation of the sausage tree, air layering is used. After layering, roots generally take 2-3 months to form, and the following spring the layer is cut off and transplanted.