Cyclocarya paliurus Seeds | Wheel Wing Nut
LATIN NAME: Cyclocarya paliurus
COMMON NAME: Wheel Wing Nut
Plant Profile
Fresh or dried leaves are steeped in hot water to give a pale, mild liquor with a honeyed finish and no bitterness at the back of the throat. Households in the hills of Guizhou and Jiangxi treat it as an everyday drink that can be taken all day, in contrast to the strong green teas of the same provinces.
Once you have seen the fruit, the genus makes sense. Cyclocarya is a single-species genus in the walnut family, and its one member is separated from the wingnuts of Pterocarya by the shape of the wing that surrounds the nut. The generic name is Greek for a circular nut, and that is precisely what it is.
In the true wingnuts the nutlet carries two narrow wings that sit on opposite sides, giving a flat, elongated outline. In this tree the wing wraps the whole nut in a disc, so the fruit reads as a small green coin, paler in the middle, with a ridged rim. Held against the light, the outline of the seed shows inside the disc.
The disc-shaped fruit is a wind-dispersal device. It is light for its size, it spins as it falls, and the flat rim keeps it aloft long enough for a breeze to carry it away from the parent trunk. Fruit hangs on the tree in long pendulous chains into the autumn, which is when the coins finish drying and turn from green to brown.
The two genera overlap in range and are easy to confuse in a mixed forest. Leaves help: this tree has pinnate foliage with seven to nine leaflets on a long rachis, and the leaflets are finely toothed and set opposite each other. The decisive character is the fruit, and the second half of the year is the only time to make the call with confidence.
Science & Biotechnology
The sweetness comes from dammarane-type saponins, with cyclocaryoside A among the compounds most closely associated with the taste, and pterocaryoside B adding to the effect. Their structure is close to that of other sweet triterpenoids found across the family. Leaf extracts also carry quercetin and kaempferol glycosides and a steady load of chlorogenic acid.
Leaf chemistry varies considerably between trees and between provenances. Flavonoid content, chlorogenic acid and total saponins all shift with genotype, light exposure and harvest date, which has made the species a subject for cultivation research aimed at producing batches with consistent composition. Shaded leaves and sun-exposed leaves do not measure the same.
Uses & Benefits
The commercial leaf comes from wild and semi-wild trees in a handful of mountain districts. Smallholders pick the leaves in summer, dry them in the shade or in low heat, and sell them either loose or compressed. Demand for the tea has grown quickly, and a market that used to depend on collection from forest margins is gradually shifting to planted orchards.
Because the tree is a narrow endemic with a valuable crop on its branches, wild stands have been stripped repeatedly. Older trees in accessible valleys carry the evidence in broken crowns. Propagation research and plantation establishment are the practical response, and the species now appears on programmes aimed at protecting and using the resource at the same time.
Beyond the daily cup, the leaf is used in longer decoctions in Chinese practice and has been studied for effects on blood glucose and lipid profiles, with much of the work published in Chinese journals. Leaf extracts also turn up in dietary supplements. The young leaves are the preferred grade, and the wood, fine and pale, is occasional furniture stock.
Growing from Seed
In the wild this is a tree of damp, fertile valley soil with reliable summer rain. Recreate that with a deep loam enriched with leafmould, a position in full sun to light shade, and room for a trunk that will eventually become a substantial tree. Drainage must still be good; the roots want moisture, not standing water.
Sow the winged fruit as soon as it is fully mature and the wing has dried, pressing it into the surface of a loam-and-grit mix and covering it lightly. Cool, moist conditions suit the seed better than warmth, and a frame or unheated shelter works well. Pot the seedlings on before the taproot starts to coil, and plant out young trees at eight to ten metres apart.
Our Take
This is a tree for a large, moist garden rather than a small border, and it rewards patience with a leaf crop you can pick every summer. Give it the same ground you would give a walnut: deep, cool and rich. Anyone planting a nut grove will enjoy comparing it with Chinese wingnut, its closest look-alike, and with the true walnuts such as English walnut. Growers in cooler districts can hedge with Chinese hickory, and Platycarya strobilacea makes an interesting companion on the same damp slope.
Related Reading
If Wheel Wing Nut appeals to you, these related plants are worth a look: