This section is from the book "The Native Flowers And Ferns Of The United States ", by Thomas Meehan. Also available from Amazon: The Native Flowers and Ferns of the United States in Their Botanical, Horticultural, And Popular Aspects.
Clammy-pubescent; leaves five to seven foliate, long-pctiolcd; leaflets lanceolate, acute, serrulate; lower bracts trifoliolate, the upper ones simple, cordate, ovate; stipules spiny; capsule smooth, shorter than the elongated stipe; seeds rugose; stem two to four feet high; petioles more or less spiny; flowers showy, purple, changing to white. (Chapman's Flora of the Southern United States. See also Wood's Class-Book of Botany.)
THE Prickly Cleome, a beautiful wild flower from the southern shores of the United States, is an object of curiosity, even to the ordinary observer, from the resemblance which the flowers bear to an insect with erect wings and long legs and tentacles. The resemblance, indeed, is not so striking as in the flowers of some orchids, but sufficiently so to produce an odd effect. To more scientific observers, however, and especially to those who like to examine structure closely, by comparing allied plants with one another, this species offers other points of peculiar interest. If the four petals and four sepals were not all turned in one direction, and if it were not for the general appearance of the seed-vessel, one would suppose at first sight that the plant belonged to the Cruciferae, or cabbage tribe; but in that family four of the six stamens are invariably long, and the remaining two invariably short, while in Cleome pungens the whole six are of equal length. The most striking difference, however, will be found in the ovarium, ultimately the seed-vessel, which in Cleome pungens is borne on the end of a very long stalk. These, then, together with some other more minute but essential peculiarities, will show at once the difference between our plant and the Cruciferae.
But there are still other plants belonging to the same natural order with Cleome which have the petals ranged with more regularity around the axis, in which the ovary is borne on a much shorter pedicel, and which, therefore, point to a much closer relationship to cruciferous plants than that suggested by the plant to which this chapter is devoted. Nor is this suggestion deceptive; for the order Capparidaceae, to which our species belongs, is closely allied to Cruciferae, and quite as much so, if not still more closely, to Resedacetae, or mignonettes. With the violets it also has some affinity, and it has therefore been classed near them. The Cruciferae comprise a very large number of genera and species, while the Capparidaceae and the Resedaceae have each but a very few; and it will be well to look for " missing links" in their development, as it is not improbable that both of them had cruciferous parentage.
A fair key to the structure of our species is supplied by the numerous bracts among the flowers. In the true Cruciferae there is nothing but a naked flower-stalk bearing pedicels and flowers, and the bracts are entirely wanting. We see, also, that the foliaceous system of our plant is very well developed, and this, in plants not absolutely acaulescent, generally implies a corresponding activity in the axis or stem. In other genera of Capparids, where there are no bracts, there is scarcely any pedicel to the flower, or to the ovary, and the resemblance to true Cruciferae is every way closer. In this species, however, the tendency to produce stems is so strong that even the petals are stalked, while the stamens have long, drawn-out filaments, and the same force has projected the ovary far beyond the point usual in flowers.
We also see the operation of rhythmical growth, or of the law of acceleration and retardation, as it is sometimes called, in producing certain other results. The pedicel is really a branch, which has started to grow from the axial bud at the base of the leaf. Its excessive slenderness, as compared with the main stem, shows us at once that its vegetative growth has been severely checked, although we notice at the same time that its power of elongation has not been interfered with to the same degree as its power for increase in thickness; but all at once it receives a sudden check to form the calyx, in which latter there is no sign of any elongating or axial growth. The growth-wave is then again somewhat accelerated in a forward direction, and produces the pedicellate or clawed petals; and finally, it is once more accelerated to a still greater degree for the production of the stamens. Thus we see that in the varying degrees of intensity in the growth-wave, and in the degree of rapidity with which the spiral line, along which the vegetative force acts, is drawn in or coiled up, we have the clew to this singular structure, and in some respects the measure of the difference between it and its allies. This, indeed, is true of all plants, but in few is it so well illustrated as in the Cleome pungens.
The great beauty of our plant makes it a desirable one to cultivate. It thrives well during the summer in any ordinary garden ground, and indeed the hotter the weather, the better it thrives. It grows about four feet high, and as it branches freely from the sides of the main stem, it makes a showy and symmetrical bush. In ordinary wild locations, unless it happens to find itself in extra rich ground, it does not usually grow more than two feet high. It is an annual in cultivation, although classed as a biennial in most descriptions.
Prof. Grisebach, a noted botanist, does not believe that plants were created all in one place, and that they have wandered over the world from one home. He is of opinion that there have been many centres of creation. But whether this be so or not as to the first appearance of plants on the earth's surface, it certainly seems to be true that our modern races have home-centres, and that from these they have wandered, and still continue to wander, farther and farther away. Most of the species of Capparidaceae are tropical or semi-tropical, but they are continually extending their boundaries. Our Cleome is believed to have crossed over to Florida from the West India Islands, and it is probable that it has been introduced into the State named only within recent times, as it is not mentioned in Torrey and Gray's "Flora of North America," which was published in 1840. Prof. Wood gives, in a general way, "the South" as its location, while Chapman places it in "Florida and westward." Mr. George D. Butler, in a note to the "Botanical Bulletin" (now the "Botanical Gazette"), reports it as having already crossed the Mississippi to Arkansas, and there is no doubt but future generations will find it completely across the continent. According to Mr. Martindale, it occasionally appears along the shores of the Delaware, being, no doubt, brought there in the ballast of vessels.
The name of the genus, Cleome, is said to be derived from the Greek verb kleio, to shut, in allusion to the fact that the style and the filaments, which lengthen faster than the petals, burst through the latter while they are still closed, and while the stigma and the anthers are still enfolded by them. Don says that the name "was first used by Theodosius," and from him adopted by Linnaeus. A species is often found described as C. spinosa, but this is now thought to be identical with C. puu-gens, which has the right of priority, as far as the name is concerned. Our species has no English name, but a translation of its botanical appellation, "Prickly Cleome" (pronounce clay-om-ay), will, no doubt, be acceptable, unless, indeed, "Spider-flower," which we have heard suggested, should be adopted in preference. We cannot, however, endorse this name, as it is so like Spiderwort, which has already been appropriated by Trades-cautia.
From a utilitarian point of view, the Prickly Cleome is useless, but it is to be hoped that its beauty will be considered a sufficient reason for its existence.