I could just say "flower bulbs" but while I'm not a taxonomist, I'll bow to the distictions between the many different groups of sometimes unrelated plants that are commonly lumped under the term 'bulb'. A true bulb is a collection of scaly, fleshy leaves closely packed on a very abbreviated stem called a 'basal plate'. Examples of true bulbs are onions, daffodils, and lilies. A 'geophyte' is just a plant that keeps its main storage organ, be it a root, tuber, corm or bulb, underground, and sends up aerial shoots from a buried growing point. Most geophytes come from regions that experience some kind of climatic extreme: of drought, or temperature, or both. Storing starch underground is one way around the unfavorable season, and to me at least a major source of their appeal: I find it absolutely fascinating to watch a flower spike emerge from the earth and open to display its beauty, where a few weeks before there was only bare earth. Bulbs are like jewels or hidden treasures that show themselves at the appointed time, like magic. This effect of 'sudden glory' is heightened in some geophytes that flower with no foliage visible at all: Nerine, Sternbergia, Colchicum, Crocus among other genera display this habit, which is sometimes called "hysteranthy".
In general, most of the geophytes I grow are from places with climates similar to that of coastal California. (See the background page for more info on this type of climate.) Most of these plants can 'take care of themselves' outside in the Bay Area. Some are a bit fussy about drainage, but others are not particular. I grow most of mine in a simple raised bed made of bricks with a lot of sand added to the soil. It helps to irrigate if we have a long dry spell in the middle of winter, but for the most part our natural rains take care of the rest: bringing the plants up in the fall and keeping them going through the late spring. During the dry summer, the plants are totally dormant, with no living foliage above ground at all. Traditional wisdom has it that they will not tolerate any summer water whatsoever, but in many cases this is simply not true. Some will not mind even if they get regular water along with other non-seasonal plants, simply remaining dormant in their pots or beds until the onset of colder weather in the fall. Others are actually what I would call 'facultatively dormant' and will continue to grow indefinitely if they do not dry off. Some Watsonias behave this way in my garden. In any case, don't be discouraged from trying winter growing bulbs just because you water your garden year round. There are bound to be some nice species that will be happy to accomodate you!
RICHES OF SOUTH AFRICA
Is there anyone so naive as to believe the Dutch were interested in the diamonds in South Africa? I happen to know the diamonds were just a pretext for their *real* target: the plants. The wealth of the South African flora is legendary, and some of the most fabulous gems are the geophytes. Everyone knows about Gladiolus, mined by the Dutch and many others to produce a myriad of showy hybrids, along with other genera like Freesia, Amaryllis, etc. (though note that what we call Dutch Amaryllis hybrids are not South African at all, being derived from the South American genus Hippeastrum.) But many people, myself included, are astonished to find that the plants that have become famous in popular horticulture are just the tip of the iceberg. There are hundreds of relatives of the commercial Gladiolus that are native to South Africa. They are members of the great Iris family, the Iridaceae, and collectively are known as Irids. Most of the South African Irids are not true bulbs but corms. When you dig them up they may look similar, but structurally they are quite different. If you slice a bulb (like an onion) in half, you see the compressed stem that I mentioned above. If you do the same with the corm of say, a gladiolus, you will find very little ultrastructure. Most of the corm is a homogenous mass of storage tissue, with little eyes or future growing points stuck here and there on the outer surface, with the main ones usually but not always at the top center. One feature of corms is that they are mostly annual, though the plant as a whole is perennial. That is, when the plant grows, it burns up last year's corm, and at the end of the season a new one is formed from a swelling of this year's plant base. When you dig a cormous plant, you will often find the old, spent corms near the current one.
Click here for an introduction to the South African Iridaceae.
The Irids, or iris relatives, are just one of many groups of flowering geophytes that are represented in South Africa. The amaryllis relatives are another. All of them that I can think of right now are true bulbs. Some have very showy flowers, but for me the most interesting feature of many of them is their foliage. Click here to see a slide show introducing these plants.
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