The Cape is well known for its wealth of beautiful bulbs. If you go walking on Lion's Head above Cape Town in early summer one of the most striking sights are the tall blue spikes of Aristea capitata, a member of the Iris family. It grows wild along the lower mountain slopes of the southwestern Cape.
The plants form thick clumps of long strap-shaped evergreen leaves, which stand upright to 1,5 metres. From October the flowering stems appear tall and strong above the leaves, often 8 or more stems grow from each clump.
The flowers are formed along the top part of the stem, tightly arranged on little branches forming small bunches of buds. There are a few hundred flowers along each stem, but they open only a few at a time and last for less than a day. The 6 bright blue petals of each flower open wide, creating a flat saucer of about 25mm across with the 3 yellow anthers and sword-shaped stigma in the center. By the afternoon the open flowers start to wilt and close with the petals twisting around each other. The flowers are pollinated by pollen - collecting bees that are active early in the day. The old flowering stems remain upright for months after flowering and are quite attractive, turning a rich brown colour. Underground Aristea capitata has a rhizome from which the plants often resprout after fire.
Growing Aristea capitata
Aristea capitata is wonderful plant for gardens in milder climates. Easy to propagate and cultivate; the plants are attractive throughout the year with evergreen leaves in neat clumps and intense blue flowers from October to November, followed by the attractive dry flower stems. Growing in the garden the plants require full sun to semi-shade and a rich soil that is well drained, but not too dry and sandy. During the winter and spring the plants require plenty of water. If one is planting an indigenous garden, this is an excellent plant to combine with restios, proteas and buchu for a fynbos look.
The best way to propagate Aristea capitata is from seed. The seeds are formed inside quite large 3-winged capsules, which turn brown and dry as the seed matures. The seed capsule splits open at the top to release the ripe seeds that are light brown, hard and flat. The best time to sow is in autumn, which is the start of the rainy season in the Cape. The seeds are sown in seed trays filled with a well-drained potting soil. After sowing, the seeds are lightly covered with milled bark or white sand, watered well and placed in the shade. Germination is usually very good and within a month. The small seedlings can be potted and grown-on in a well-drained, rich medium. The young plants only start to flower after about 3 years. Mature plants can be transplanted and divided after flowering, but this should only be done if really necessary. Lift the clumps with care and make sure that the rhizomes do not dry out. The plants should not be out of the ground for long. Keep the ground moist till the plants are established.
At Kirstenbosch a selection of Aristea capitata with beautiful pink flowers blooms at the same time in the garden. Aristea ecklonii is much smaller than Aristea capitata and prefers shaded places along forest margins, and is a very tough species found in many gardens.
In the genus Aristea there are approximately 55 distributed throughout Africa and Madagascar, most of them with brilliant blue flowers. Several are beautiful, but unfortunately not all of them are so easy to grow.
Author: Liesl van der Walt
(Name updated August, 2008)