Cyclobalanopsis Seeds | Ring-cupped Oak

Brown Ring-Cupped Oak acorns, each in a cup marked with concentric rings — Ring-Cupped Oak (*Cyclobalanopsis*): Fagaceae, a group of evergreen oaks from the forests of East and South-East Asia.

LATIN NAME: Cyclobalanopsis

COMMON NAME: Ring-Cupped Oak

Plant Profile

Ring-Cupped Oak is the common name for the group of evergreen oaks whose acorn cups are made of concentric rings of scales rather than the spirally arranged scales of ordinary oaks. The trees are tall and rounded, with glossy, leathery, often toothed leaves that stay on the tree for two or three years.

The group is native to the warm-temperate and tropical forests of East and South-East Asia, from the Himalayas and southern China through Japan to Indonesia. Some eighty species are recognised, and they are among the dominant canopy trees of the evergreen forests of the region. The leaves of many species are crowded at the ends of the twigs, and the acorns ripen in the second autumn after flowering.

Science & Biotechnology

Cyclobalanopsis is treated by most modern taxonomists as a subgenus of Quercus, Quercus subgenus Cyclobalanopsis, on the basis of molecular work that places it within the oak genus. The ring of fused scales in the acorn cup is the character that gives the group its name, and it is unique among oaks.

The group is important in studies of Asian forest ecology, since its species dominate the evergreen broad-leaved forests of southern China and Japan, and their acorns are a major food source for wildlife. Many species are also valued for timber and for their tannin-rich bark.

Uses & Benefits

The timber of the larger species is hard and durable and is used for construction, furniture and charcoal. The acorns are eaten by wildlife and, after leaching, by people in times of scarcity, and the bark has been used for tanning and for dyeing.

In the garden the group is grown for its evergreen canopy and its handsome foliage, though individual species are less often planted than the deciduous oaks. They need a mild, humid climate and shelter when young, and they are slow to establish. Several species are also planted as street trees in southern China and Japan, where their evergreen crowns tolerate pruning and air pollution. The acorn cups of some species are so regular that they are used in teaching as examples of ringed scales.

Growing from Seed

Sow fresh acorns in autumn in deep pots, keeping them moist and cool; they lose viability if they dry out. Germination follows in spring, and the taproot develops quickly, so pot on before it coils.

Plant out in deep, humus-rich, well-drained soil in sun or part shade, and mulch to keep the roots cool. Water through the first two or three summers, and protect the young tree from wind. Most species are hardy to about -10 °C, but they crop best in a mild, humid climate. In a garden, acorns are best sown where the tree is to stand, since the taproot makes transplanting difficult after the first year.

Our Take

A group rather than a single species, and the ringed acorn cup is the mark of it. Grow it as you would any evergreen oak: shelter first, then patience.

Tree Seeds