Tetradium daniellii Seeds | Evodia
LATIN NAME: Tetradium daniellii
COMMON NAME: Bee Bee Tree
Plant Profile
The bee-bee tree is a broad, round-headed tree of eight to twelve metres, with smooth grey bark and opposite, pinnate leaves of five to nine glossy leaflets that smell faintly of citrus when crushed. It is dioecious, and both sexes flower, but only the female trees carry the crop of small, reddish, four-lobed capsules that split in autumn to reveal shiny black seeds. What makes the tree remarkable is the flowering: in July and August, when the spring flush is long over, it covers itself in wide, flat heads of tiny white flowers that are so heavily visited by bees that the whole crown hums. It comes from northern China and Korea, and it is one of the best late-season nectar sources available to a temperate garden. It is also, unfortunately, one of the least planted.
Science & Biotechnology
Tetradium is a small genus in the Rutaceae, split from Euodia, and it sits close to the citrus tribe. The bee-bee tree’s chemistry is dominated by flavonoids and by traces of the quinazoline alkaloids that characterise its better-known relative, Tetradium ruticarpum — the source of wu zhu yu, one of the warmer drugs in Chinese medicine. Evodiamine and rutaecarpine from that species are the subject of a large pharmacological literature, with thermogenic, vasodilatory and anti-inflammatory activity reported, and evodiamine has been studied as a TRPV1 ligand. The ornamental tree contains these compounds only in small amounts, and it is not a substitute for the drug. The dioecious breeding system is the reason seedling crops vary: a good fruiting form needs a male nearby, and named clones are the only way to be sure of what you are getting.
Uses & Benefits
It is planted for honey and for pollinators. The nectar flow is heavy and reliable, the flowers are open in the dearth of high summer, and beekeepers in parts of Europe and North America regard it as one of the best trees they can plant. In the garden it makes a good lawn specimen with clean foliage, interesting autumn capsules and yellow autumn colour, and it is tolerant of most soils, including chalk, and of urban air. It is not a street tree for a narrow pavement, because the crown is broad and low, and the female trees drop fruit that can be messy on paving. The wood is soft and of no commercial value. The tree is also useful as a quick screen at the back of a large border, since it grows fast when young.
Growing from Seed
The seed is black and hard-coated and benefits from three months of cold, moist stratification; sow it in autumn in a pot of gritty compost and leave it outside, or stratify it in the refrigerator and sow in spring. Germination is usually in April and can be uneven. The seedlings are fast and hungry, so pot them on promptly and grow them in full sun. Plant out in autumn or early spring, in any reasonable soil, and stake the young tree for two years. Prune in winter if the crown needs lifting, since the tree bleeds little at that season. Plants from seed will be a mix of sexes, so if fruit and seed are wanted, keep several and remove none until they flower.
Our Take
One of the best pollinator trees for a temperate garden, and one of the least known; plant it for the hum in July.
Related Reading
Gardeners who grow Bee Bee Tree often pair it with these related subjects: