Cornus controversa Seeds | Wedding Cake Tree
LATIN NAME: Cornus controversa
COMMON NAME: Wedding Cake Tree
Plant Profile
The wedding cake tree is named for its architecture, and the name is exact. The branches leave the trunk in whorls at intervals of thirty to sixty centimetres, each whorl held almost perfectly horizontal, so that a mature tree reads as a series of green plates stacked one above the other. Trees reach ten to fifteen metres in cultivation, and old specimens in the wild can be taller and wider, with a trunk that eventually leans and divides. The leaves are the botanical surprise: unlike the familiar flowering dogwoods, which carry their leaves in opposite pairs, this species arranges them alternately along the shoot.
In early summer the tree produces flat, slightly convex heads of small creamy white flowers, ten to fifteen centimetres across, one at the end of nearly every branch, so that the whole tiered structure is outlined in white for a fortnight. The fruits that follow are small, round and blue-black, held on bright red stalks, and they are taken by thrushes and warblers as soon as they colour in early autumn. Autumn foliage is a deep purple-red, strongest on the upper surfaces of the tiers, and it lasts well into November. The species is native to the mixed forests of China, Korea and Japan, from about five hundred to two thousand metres, often on the edges of clearings and along streams, and it is a tree of cool, moist, humus-rich ground rather than of hot, dry sites.
Science & Biotechnology
The tiered habit has attracted developmental botanists for a century. The pattern comes from rhythmic extension: the shoot grows in a burst, sets a whorl of leaves and lateral buds, pauses, and then extends again, with the laterals held in check by the terminal bud until the next flush. When the terminal shoot is damaged, the uppermost laterals take over and the regular stacking breaks down, which is why coppiced or frost-damaged trees lose the wedding cake form permanently. Work on the genus has also clarified the phylogeny of the alternate-leaved dogwoods, which turn out to sit near the base of the Cornus tree rather than among the opposite-leaved species, and the blue-black fruited group to which this species belongs is now recognised as a distinct clade.
The fruit has been studied for its pigment and lipid content, since the blue-black drupes are rich in anthocyanins and in fatty acids that make them valuable to migrating birds. The species also appears in work on forest regeneration in East Asia, where it is a gap-coloniser that establishes in small openings and then persists in the understorey for decades, flowering best where it receives some direct light. There is one persistent confusion in the literature that is worth correcting: the medicinal dogwood of Chinese pharmacy, Shan Zhu Yu, is Cornus officinalis, a small tree with red fruits and yellow spring flowers. The wedding cake tree is a different species entirely and has no place in that prescription.
Uses & Benefits
The tree is grown as a specimen, and there is not much else to say about its garden role, because one well-sited plant is enough for most gardens. It needs space to show the tiering, and it needs to be seen from below or from a distance, so it belongs on a lawn, at the edge of a woodland, or across a pond rather than in a mixed border. The white flower tiers in June and the purple autumn colour give it two seasons, and the bare tiered framework in winter is a third. It is also a good tree for wildlife, since the fruit is taken eagerly and the flat flower heads are worked by a wide range of small bees and hoverflies.
The wood is hard, close-grained and pale, and has been used for tool handles, turnery and small domestic items, though the tree is too slow and too valuable as an ornamental to be grown for timber. In Japan and China it is planted in temple grounds and parks, where old specimens develop a broad, layered crown of considerable dignity. Named selections exist, including a form with white-margined leaves that is slower and smaller and must be propagated by grafting, since it does not come true from seed. The species tolerates air pollution reasonably well and can be used in larger urban plantings, provided the soil is good and the site does not bake in summer.
Growing from Seed
The seed has a double dormancy and will not germinate in a single season without help. Clean the flesh from the drupes, then give the seed a warm, moist period of three to four months at around twenty degrees, followed by three months at four degrees. In practice this means sowing into a bag of moist peat or coir in late summer, keeping it warm through autumn, and then moving it to the refrigerator over winter, or simply sowing outdoors in a frame and waiting two springs. Germination is erratic even when the treatment is right, and a proportion of seed may come up in the second year.
Prick the seedlings out into deep pots as soon as they are large enough, since the root is vigorous, and grow them on in light shade with steady moisture. Plant out in autumn into deep, humus-rich, well-drained soil, with shelter from strong wind while the tree is young, and stake for the first three years. Do not prune the leading shoot, because the tiered habit depends on an undamaged terminal bud. Remove only dead or crossing wood in winter, and keep a mulch of leaf mould over the root zone. The tree is hardy to about minus twenty-five degrees once established.
Our Take
This is one of the few trees that is worth planting for its shape alone, and the flowers and autumn colour are extras. Give it good soil, shelter and room, and do not prune it, and it will build the tiers by itself.
Related Reading
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