Wednesday, June 4, 2008

Curly Bulbs in Springtime

Cyrtanthus species with leaves and fruit, May 2008.

The arid and semi-arid portions of South Africa are home to a tremendous diversity of succulent plants, and also—though it isn’t as widely appreciated—a very diverse flora of geophytes (bulbs and tuberous plants with underground storage organs). Manning, Goldblatt and Snijman, in The Color Encyclopedia of Cape Bulbs (Timber Press, 2002) estimate that there are about 1200 species of geophytes just in the zone of winter rainfall centered around Cape Town. I cultivate a small collection of South African geophytes, and this is generally a pretty dull time of year in that corner of the greenhouse: most are winter growers, and by this point in late spring the winter growers have crashed. There won’t be any sign of life from pots of Lachenalia, Massonia and Cape Eriospermum species until September or October.

A few South African bulbs that I grow come from the eastern parts of the country, where rainfall tends to be heaviest in summer, and these provide a nice change of pace from the brown leaves and withered flowers that dominate the rest of the bulb collection. Possibly the nicest summer bulb I have is the little Cyrtanthus with corkscrew leaves pictured here. I started these plants from seed from Silverhill Seeds, a source that specializes in the flora of South Africa. The material came labeled as Cyrtanthus helicatus, but that doesn’t seem to be a legitimate name.
There are about 57 species of Cyrtanthus, a genus in the amaryllis family (Amaryllidaceae), native to a wide range of habitat types in Sub-Saharan Africa. The species from Silverhill is one from a seasonally dry, summer-rainfall area, and it is leafless and inactive all winter. During the cooler months, the bulbs don’t receive any water at all. It blooms in April, before leaves emerge, with just a single white, amaryllis-like flower per plant, so far as I’ve seen. The leaves always seem to be produced two per bulb per season, giving the plants an amusing double helix look. While the leaves are green, I water the plants whenever the soil surface shows signs of drying out, so that moisture is always available to the roots. Even with diligent watering, the bulbs tend to go dormant before midsummer.

This year, I managed to cross-pollinate several of the Cyrtanthus plants, and the fat seedpods in the photograph are the result. I’ll probably plant the seed as soon as it ripens, since seed of plants in the amaryllis family is often short lived. (Dry, black, papery seeds of the type seen in Cyrtanthus are usually much more forgiving about storage time than the fleshy seeds of some other amaryllids, but better safe than sorry.) At least under my conditions, Cyrtanthus is quick to germinate, but with an awfully long wait for seedlings to reach maturity, even if maturity only means a bulb the size of an olive. I wouldn’t expect the new seedlings to flower before 2013 or so.

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