Friday, May 1, 2009

Lachenalia patula: a Bulb with Succulent Leaves

Lachenalia patula in late March. Material from Liebendal, near Vredendal, Western Cape, South Africa.

Bulbs with truly succulent aboveground leaves are almost unheard of: the whole point of having a bulb is that the foliage leaves can be active when growing conditions are optimal, and be dropped as soon as heat, drought or cold brings growth to a halt. In the majority of bulbous plants, even those from deserts, the only significant storage of water and nutrients occurs in the modified subterranean leaves that form the bulb itself. Lachenalia patula is almost unique*, as a bulb with chunky, low-surface-area foliage leaves full of water-storing tissue.

Lachenalia patula is a winter-growing bulb from arid areas in the Western Cape of South Africa. As far as I know, it is restricted to the southern parts of a desolate-looking but botanically rich area called the Knersvlakte, on flats and rolling hills often covered with white quartz pebbles. The bulbs of L. patula are small compared to the rest of the plant, only about 1 cm across, and covered in blackish tunics. Most of the approximately 70 species of Lachenalia come from seasonally moist habitats in the winter-rainfall zone of South Africa, and have thin leaves. Lachenalia patula’s succulent leaves may be a special adaptation to harsh conditions in the Knersvlakte.

In cultivation, L. patula needs very strong sun, and does well in cramped pots of poor, well-drained soil. In winter, the soil should be kept just slightly moist at all times: don’t let it stay soggy, but be sure that the leaves don’t start to wilt. The flowers tend to emerge in late March for me, and have a moderately strong sweet smell. They always seem to bloom about a week too early to look good for the CCSS Show. The plants rapidly go deciduous in April, as the seed ripens. As with other winter bulbs, the pot can be stored somewhere out of the way and neglected during the long warm weather dormancy.

Lachenalia patula can be propagated by seed, which are best sown in early autumn, and take two to three years to yield flowering-sized bulbs. The seedlings are agreeably peculiar little things, with perfectly cylindrical leaves, as opposed to the channeled leaves of adult plants. Like other lachenalias, L. patula can also be started from leaf cuttings, which are most likely to succeed if taken early in the growing season, as soon as the leaves are expanded.

*A few species of Drimia and Ornithogalum, including the weird O. unifoliatum, also have convincingly succulent foliage leaves.


Julie said...

How interesting, Matt! What a wonderful post. I have virtually no bulbs down here that will do well outside. (Well Amaryllis do well in pots here). I know you say here that they like to be in crowded pots in poor soil...OK...I have the poor, quick draining sandy soil outside...but do you think they could thrive here in full sun in a outdoor bed? I think we kind of mimic the SA climate (? maybe) here in south Florida!

Matt said...

I have a feeling that your weather would be on the hot and humid side for most SA bulbs, but it might be worth trying some. Lachenalia aloides (Cape Cowslip) is nice, and commonly available in garden centers in spring.