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Virgilia Divaricata – The Tree of Choice

Also known as Keurboom, Tree-In-A-Hurry and Blossom Tree.
This tree is leguminous meaning it is a nitrogen fixer.

Growing Virgilia

The attractive fragrant flowers and the fast growth rate make the keurboom a popular tree for the garden. Of the two, Virgilia divaricata is the better choice as its foliage is more luxuriant, and its growth more compact and it is amazingly beautiful when in full flower.

A keurboom is the perfect tree for the new, bare garden because it grows so fast it will take only two or three years before it will be creating shade, or a screen, and filtering the wind – which is an important consideration in Cape Town suburbs. It is also one of the best species to use as a pioneer in the first stage in the succession to forest. It is happy to grow out in the open, grows fast and quickly and creates the shade that the slower-growing, more permanent trees need to grow in.

Virgilia is propagated from seed. The seed coat is hard and requires some stimulation to initiate germination. Seeds can be soaked in hot water before sowing, or the seed coat can be cracked artificially. They also respond to stimulation by fire and can be treated with the Kirstenbosch Instant Smoke Plus Seed Primer. Seed should be sown in autumn or spring, in well-drained soil at a depth of 0.5 – 1 cm and covered with the sowing medium or milled bark and then watered. Seed can also be sown in situ, e.g. for forest rehabilitation projects. The seeds are highly fertile and can remain alive for many years after they have fallen, even after as many as 30 years they will germinate if conditions are favourable.

Transplant the seedlings after the first pair of true leaves has emerged when they are large enough to handle. Virgilia seedlings grow fast and can be planted into pots or bags for growing in, or directly into their permanent position in the garden. Feed moderately with a liquid fertilizer and water generously. Plant the young trees into a permanent location in full sun or semi-shade. They need good, light soil and plenty of water, particularly during their first 2 to 6 years. Virgilias have strongly spreading surface roots and are greedy feeders; they will benefit from frequent generous applications of compost or organic mulch. Virgilias are sensitive to frost, particularly when young. Mature trees may withstand short periods of frost, but not prolonged exposure to freezing temperatures.

References

  • Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of southern Africa, edn 3. Struik, Cape Town.
  • Goldblatt, P. & Manning, J. 2000. Cape plants. A conspectus of the Cape flora of South Africa. National Botanical Institute, Pretoria & Missouri Botanical Garden.
  • Palmer, E. & Pitman, J. 1972. Trees of southern Africa. Balkema, Cape Town.
  • Phillips, E.P. 1928. Virgilia capensis. The Flowering Plants of South Africa 8: t. 305.
  • Smith, C.A. 1966. Common names of South African plants. Memoirs of the Botanical Survey of South Africa No. 35.
  • Van Wyk, B. & Van Wyk, P. 1997. Field guide to trees of southern Africa. Struik, Cape Town.

Giles Mbambezeli & Alice Notten
Kirstenbosch National Botanical Garden
August 2003

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