Tetradium ruticarpum Seeds | Evodia
LATIN NAME: Tetradium ruticarpum
COMMON NAME: Evodia
Plant Profile
Evodia is a small, spreading deciduous tree of the rue family from the hills of China and Korea, growing five to eight metres tall with a rounded crown of compound, aromatic leaves. In late summer it carries broad, flat clusters of small greenish flowers, followed by clusters of small reddish fruits that split to reveal shiny black seeds.
It wants full sun and deep, fertile ground, and it stands urban conditions better than most rutaceous trees. The whole plant smells faintly of its family: bruised leaves give the citrus-and-pepper scent characteristic of the rue family. The young branches are velvety with fine hairs, and the compound leaves carry nine to fifteen leaflets that turn an unremarkable yellow in autumn before dropping. The fruits split into four valves when ripe, exposing the shiny black seeds in a display that gives the tree a second, brief ornamental season before the leaves fall.
Science & Biotechnology
The fruit, Wu Zhu Yu, is a major Chinese warming herb, and its alkaloids, evodiamine and rutaecarpine, have been intensively studied for thermogenic and circulatory effects, making the species a standing subject in pharmacological literature.
Its nectar production has earned its relatives the name bee-bee tree in Western beekeeping circles, and phenological studies of the genus rate it among the best late-season pollinator trees, flowering when little else is open. Chemical work has isolated the fruit’s volatile oils alongside its alkaloids, and studies of evodiamine have grown into a substantial literature since the compound became a standard tool in metabolic research. Its relationship within the genus has been clarified by molecular work, which separated Tetradium from the old catch-all Euodia and settled the names of the East Asian species.
Uses & Benefits
In the garden its main work is for pollinators: the late-summer flower clusters feed honeybees and wild bees at a season when most trees have finished, and the aromatic foliage is untouched by deer.
The fruit has a long record in Chinese medicine for cold headaches and digestive discomfort, a professional matter; in the garden the tree is grown for shade, scent and bees, and it asks little once rooted. Beekeepers who plant it rate the late-summer flow highly, and the dried fruits retain their pungent aroma for years, which is how the trade grades and stores them. In traditional use the dried fruit is one of the standard warming herbs of the Chinese pharmacopoeia, and its pungent, slightly toxic character marks it strictly professional.
Growing from Seed
The seeds sit inside small reddish fruits and germinate best sown fresh: clean them, sow in autumn into pots of free-draining compost, and leave the pots outdoors through winter, or chill them for two months before spring sowing.
Grow the seedlings on in full sun, pot them on yearly, and plant out into deep soil with room for the crown. Feed moderately in the first three years, then leave the tree to its own rhythm; it needs little pruning beyond deadwood. Collect the fruits when they redden and split, clean the seed from the black coats promptly, and never let the cleaned seed dry out fully before autumn sowing. Young trees grow quickly in their first three years, so stake them early and remove the stake once the trunk thickens, usually by the fourth season.
Our Take
A small tree with one great season: late-summer clusters that keep the bees working when the year is ending. Chill the seed, give it sun, and stand back.
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