Castanopsis sclerophylla Seeds | Hard-leaved Chinkapin
LATIN NAME: Castanopsis sclerophylla
COMMON NAME: Hard-Leaved Chinkapin
Plant Profile
Hard-leaved chinkapin is an evergreen tree, ten to fifteen metres tall, with a dense, rounded crown of leathery leaves that are oblong to lance-shaped, sharply toothed in the upper half and glaucous beneath. The bark is grey and smooth on young trees and finely fissured on old ones, and the trunk is often short, dividing low into heavy limbs. The new growth is soft and reddish, and the foliage darkens through the season to a deep, slightly dull green that lasts all winter.
The acorns are enclosed for most of their development in a cupule covered in sharp, spiny scales, which gives the tree its other name, and they are released in autumn as small, round, brown nuts about a centimetre across. They are eaten by squirrels, mice and wild boar, and they were also eaten by people, after processing, across the hills of Zhejiang, Jiangsu, Anhui and Jiangxi. The species is native to the evergreen broadleaved forests of eastern and southern China, generally below eight hundred metres, on acid, well-drained soils in warm, humid conditions. It is one of the dominant trees of the lauriphyllous forest that survives in fragments around temples, villages and inaccessible slopes.
Science & Biotechnology
The species is a component of the evergreen broadleaved forest of subtropical China, one of the most threatened vegetation types in the country, and much of the research on it concerns the structure and dynamics of those remnants. Studies of old-growth fragments in Zhejiang and Fujian have recorded it among the canopy dominants, along with Castanopsis eyrei, Schima superba and various laurels, and have shown that the forest depends on a mosaic of small gaps for regeneration. The tree is shade-tolerant as a seedling, responds to gap formation with faster growth, and can persist in the understorey for decades before reaching the canopy.
The acorns are chemically defended by tannins, which is why they must be leached before eating, and the tannin content has been measured in both the nut and the cupule. Work on seed dispersal has shown that rodents are the main agents, caching the nuts in shallow soil and losing a proportion to germination, and that the size of the crop varies greatly between years. The species forms ectomycorrhizal associations, and its roots host a fungal community that differs from that of the surrounding pines and oaks. Work on its wood anatomy describes a dense, hard timber with narrow vessels, consistent with the slow growth of an evergreen canopy tree.
Uses & Benefits
The best-known use is culinary and regional. The acorns are gathered in autumn, cracked, soaked and boiled repeatedly to remove the tannins, then ground and cooked into a dark, firm jelly sold as bitter chinkapin tofu. It has a mild, slightly bitter, nutty flavour and is eaten cold with soy sauce, chilli and sesame oil, or stir-fried. The processing is laborious, and the food is now largely a seasonal speciality rather than a staple, but it remains a marker of local identity in the hills of Zhejiang and Anhui.
The wood is hard, heavy and durable, and has been used for tool handles, furniture and construction, and the tree is cut for fuel in some areas. In the landscape it is planted as an evergreen shade tree and for reforestation of degraded hill land, where its tolerance of acid, poor soils and its dense crown make it useful. In the garden it is a slow but handsome evergreen, best grown as a specimen on a large property or in a woodland garden, where its leathery foliage and its autumn acorns can be appreciated. It is not suitable for small gardens or for alkaline soils.
Growing from Seed
The acorn is recalcitrant and should be sown as soon as it is collected, in autumn, in a deep pot of loam, leaf mould and grit. Cover it lightly and keep it cool and moist; germination takes four to eight weeks and the radicle goes down fast, so the pot must be deep. Protect the pots from rodents, which will find the acorns even under a layer of mesh. Do not allow the compost to dry out at any point.
Prick the seedlings out before the taproot fills the pot, and grow them on in a shaded frame, moving them into more light in their second year. Plant out in autumn into deep, acid, well-drained soil, with shelter while the tree is young, and mulch with leaf mould. Keep the ground clear of grass and weeds for the first three years. Growth is slow at first, then steady at thirty to forty centimetres a year. The tree begins to fruit at around ten to fifteen years, and it can live for several centuries.
Our Take
A tree of the old hill forests, worth growing for its evergreen canopy and its place in a vanishing landscape. Sow the acorns fresh, give it acid soil and shade while young, and it will outlast the garden.
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