The seasonal confusion about colchicums

Press, 23 February 1978, Page 12

The seasonal confusion about colchicums

As autumn approaches, sc does the annual conversation with a visitor: “I do like your autumn crocuses.” “Nice, aren’t they? Actually, they’re colchicums.” “Oh 1 thought they were autumn crocuses.” “That’s what they’re called. But they aren’t really crocuses.”

It is all very confusing, because to the lay eye a colchicum flower, known as an autumn crocus, looks pretty much like an autumn-flowering crocus. The two are really very different. Some of the differences are obvious: colchicums have six stamens, crocuses three; colchicums have three styles, crocuses only one, which splits into three branches near the top.

But it is the difference that is not visible from the outside that really counts, because it is sufficient to put the two into different families. In the

colchicum the ovary is superior. This is not a blow against sexism but a botanical classification that means the ovary (or embryo seed capsule) is inside the perianth tube (the stem on which the flower appears), putting the colchicum in the lily family, Liliaceae. The ovary of the crocus is below the perianth tube and this, with other characteristics, puts the crocus in, of all things, the iris family, Iridaceae.

Some 40-odd species of colchicum have been named, but the differences between many of them are so subtle that only highlytrained taxonomists can detect them.

Those commonly grown in gardens belong to three main groups: Colchicum autumnale and its relatives, which include the most free-flowering of all, C. byzantinum; the Colchicum speciosum group,

which includes the absolutely glorious (and priced to match) double form named “Waterlily:” and the species with tesselated (chequered) flowers, of which the most common, and probably the best, is Colchicum agrippinum (this means “Like a wild olive,” but why on earth it is called this I do not know). I have flowers of the first and third groups on the table before me as I type; the flowers of the speciosum group are not yet out, but when they do appear they will be easy to identify because they are the largest and most handsome in the genus.

Colchicum autumnale is the first to appear, but its close relative byzantinum is not far behind. Just about the only difference in appearance that the amateur can detect between their flowers is that in byzantinum the perianth segments (the bits that look like petals) have a distinct keel; the segments of autumnale do not. Byzantinum has something else that sets it above autumnale; an incredibly free-flowering habit. Colchicum autumnale produces, with luck, four,or five flowers from each corm; byzantinum has been knbwn to produce 20 or more.

There are differences, too, in the size and shape of the leaves (byzantinum has wider leaves, with distinct ribs), but these are not. much help at flowering time (“Naked boys” is one of the English common names for colchicums because the flowers appear before the leaves). The corms of C. byzantinum are an infallible clue to its identity: they are the largest of the family, knobbly and irregular, not unlike a clenched fist. Actually, the corms are one of the most interesting things about all colchicums, and it is worth di-

gging up one or two for a look.

They vary from pigeonegg size to fist size, and have one feature in common: a foot-like projection from the base. If the tunic (outer casing) is removed, it will be seen that a groove runs up the outside, from the bottom of the foot. This groove widens at the base, forming a small hollow, and from this hollow next season’s growth will start. So interesting a plant must have some interesting end uses; and colchicums are not disappointing in this department. If I suffered from gout this would be my favourite plant, because all its parts contain a drug, colchicin, which has been'used for hundreds of years as a remedy for this ailment. Even the ancient

Greeks knew about it. A coichicum is not something to be nibbled, however, because the whole plant is poisonous to all animals, including humans — and an unpleasant aspect of coichicum poisoning is that it takes a long time to die. Oddly enough, its dried leaves go into the hay made in the alpine meadows of Europe, where colchicums grow wild, but the cattle suffer no ill effect. Possibly the poisonous substances' disappear on drying. No less an eccentricity could be expected from a plant that can grow in blazing sun or densest shade, and will even produce flowers from a dried-out corm — flowers, moreover, that when picked will stand quite happily for several days in a vase without water.