Lachenalia viridiflora W.F.Barker
Lachenalia viridiflora is a most appealing autumn- and winter-flowering bulbous plant, growing up to 200 mm high. Its startling turquoise blooms place it among an exclusive group of plants with turquoise, greenish-turquoise or sea-green flowers that include the exquisite green ixia, Ixia viridiflora, from Western Cape, and the dazzling jade vine, Strongylodon macrobotrys, from southeast Asia. Although critically endangered in its native habitat, the ease with which L. viridiflora can be cultivated as a pot subject has endeared it to gardeners around the world.
Lachenalia viridiflora is a winter-growing, dwarf, bulbous geophyte with a soft fleshy bulb and two lance-shaped, suberect leaves, that may either be plain green or heavily marked with dark purplish brown spots on the upper surface. In late autumn and early winter it produces a many-flowered inflorescence of long, tubular blooms in shades of turquoise or greenish turquoise, reaching 80-200 mm in height in full bloom. The flowers are unscented and last up to two weeks. The fruit is a dry membranous capsule containing numerous small, black, rounded seeds with a very shiny seed coat. The bulbs undergo a pronounced dry dormant period in summer.
Distribution and habitat
L. viridiflora is probably the rarest of all the members of this endemic Namibian and South African genus of about 115 species, and is restricted to just one locality on private land on the Cape west coast, where it is critically endangered due to the construction of holiday homes. If urgent measures are not taken to protect it, it will become extinct in nature within the next decade.
Derivation of name and historical aspects
L. viridiflora was discovered relatively recently by Mr Harry Hall, a former Kirstenbosch horticulturist in charge of succulent plants, who found it in the mid 1960s on the Cape west coast. The species was described in 1972 by the first Curator of the Compton Herbarium at Kirstenbosch, Miss W.F. Barker, and named viridiflora due to the distinctive turquoise or greenish-turquoise colouring of the flowers.
In its natural habitat, L. viridiflora occurs in full sun in depressions of granite outcrops that become waterlogged during the winter months. It grows in an acid, humus-rich medium and its small, fleshy bulbs rest just beneath the soil surface. The bulbs produce offsets (daughter bulbs) that form clumps and grow in colonies amongst low, succulent vegetation. It is one of the most early-flowering of all the lachenalias, its flowering period extending from mid-May to early July in the Southern Hemisphere. The long, tubular flowers contain nectar and are pollinated by lesser double-collared sunbirds that probe the flowers with their long, curved beaks from the ground, as the flower stems are too short and weak to provide a suitable perch. As temperatures rise towards the end of spring, the leaves begin to die back, the seed capsules split open, releasing their seeds, and the bulbs enter a completely dry, summer-dormant period from October to late March.
Growing Lachenalia viridiflora
Although L. viridiflora is one of the rarest members of this genus in the wild, it is one of the easiest to grow and is being cultivated in specialist bulb collections all over the world. It is most suitably grown as a container subject in a very well-drained medium such as equal parts of coarse river sand or silica sand (swimming pool sand), and finely sifted acid compost or finely milled acid bark. In the Southern Hemisphere it grows best in plastic pots (20-25 cm diam.) placed in a position preferably receiving full morning sun and afternoon shade. In cold climates of the Northern Hemisphere, it does well in terracotta pots and requires the protection of the cool greenhouse as it is frost tender.
The bulbs are planted in early autumn at a depth of 1-2 cm below soil level and should be watered well and then not again until the leaf shoots appear, after which a good drench once per week is suggested. Offsets develop readily and these can be removed when large enough during the summer dormant period.
Seeds form easily after hand pollination and are sown 3-4 mm below the soil surface in mid-autumn in the same medium recommended for mature bulbs. Take care not to sow too thickly to prevent the occurrence of damping-off fungi, and water the seedlings with a fine spray every few days. Germination of fresh seeds occurs within two to three weeks, and the seedlings usually flower for the first time in their third year or sometimes even in their second year under ideal conditions.
L. viridiflora can also be propagated by leaf cuttings. Both the upper and lower portions of the leaf can be used for this purpose and it is done by cutting off a whole leaf at the very base, just below soil level, and then cutting it in half. Place the cuttings in slightly damp river sand in deep seed trays so that the lower 20 mm rests below the surface, and place in a lightly shaded but well-aerated aspect. After about one month bulblets begin to form that can be separated during the summer dormant period and planted out in the normal way the following autumn.
The bulbs of all Lachenalia species, especially L. viridiflora, are highly susceptible to attack by mealy bug, causing them to disintegrate, and slugs and snails are very partial to the foliage.
- DUNCAN, G.D. 1988. The Lachenalia handbook. Annals of Kirstenbosch Botanic Gardens 17. National Botanical Institute, Cape Town.
- DUNCAN, G.D. 2002. Just holding on-spectacular geophytes in peril. Veld & Flora 88: 145-147.
- JEPPE, B.J. & DUNCAN, G.D. 1989. Spring and winter flowering bulbs of the Cape. Oxford University Press, Cape Town.
Kirstenbosch National Botanical Garden
Plant Type: Bulb
SA Distribution: Western Cape
Soil type: Sandy
Flowering season: Winter
PH: Acid, Neutral
Flower colour: Blue
Aspect: Full Sun, Morning Sun (Semi Shade)
Gardening skill: Easy