Cercis siliquastrum Seeds | Judas Tree
LATIN NAME: Cercis siliquastrum
COMMON NAME: Judas Tree
Plant Profile
Cercis siliquastrum flowers on bare wood in April, and the flowers come out of the trunk and the old branches as well as the twigs. That habit, cauliflory, is common in tropical trees and rare in a Mediterranean one, and it is the reason the tree is grown. The flowers are a clear pink-purple, pea-shaped, and they open in clusters that run along the bark.
The leaves follow the flowers and are round, heart-shaped at the base, blue-green above and slightly grey beneath. The tree is small, seldom more than eight metres, with a rounded crown and a dark, scaly bark that becomes furrowed with age. In the eastern Mediterranean it grows on rocky limestone slopes and in maquis, often in the shade of larger trees.
Science & Biotechnology
Cercis is in the Fabaceae but it does not nodulate. It has no root nodules and no rhizobial partnership, which is unusual in the subfamily Caesalpinioideae where nodulation is otherwise common. The tree therefore depends on mycorrhizal fungi and on leaf litter rather than on fixed nitrogen, and it grows best on soils where those fungi are present.
The cauliflorous flowering is a mechanical solution. The flower buds are formed on old wood the previous summer and are held under the bark, and the tree has enough stored carbohydrate in the trunk to open them before the leaves can supply any. That is why a hard-pruned tree flowers poorly: the wood that carries the buds has been removed.
Uses & Benefits
The flowers are edible and are eaten raw in salads or pickled in the Balkans and in Italy, with a sharp, slightly acid taste. The unopened buds are used as a substitute for capers in some districts, and the green pods are eaten when very young, though the mature seed is bitter and should not be eaten.
The tree is grown mainly as an ornamental, and the wood is hard, dark and takes a polish, so it is used for small turned work and for veneer. Extracts of the bark appear in local medicine as an astringent, and the tree is planted in Greece and Turkey for honey, since the flowers open when little else is in bloom.
Growing from Seed
Seed needs scarification. Pour boiling water over it, leave it to soak for a day, and sow the swollen seed in a free-draining mix at 20 degrees. Germination is usually in three to six weeks, and untreated seed can sit for a year.
The tree wants full sun and a calcareous, well-drained soil, and it resents being moved once established. Plant it small, in autumn, and do not prune it hard: the flowers are carried on old wood, and a severe cut removes several years of display. It is hardy to about minus fifteen and tolerates drought once the taproot has reached moisture.
Our Take
Grown for three weeks in April, when the bare branches are covered in pink. Plant it where you will see the trunk, not just the crown.
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