I have left Cypripediums to the last, in these hasty notes, because that supremely interesting genus demands more than a record of dry facts. Darwin pointed out that Cypripedium represents the primitive form of orchid. He was acquainted with no links connecting it with the later and more complicated genera; some have been discovered since that day, but it is nevertheless true that "an enormous extinction must have swept away a multitude of intermediate forms, and left this single genus as the record of a former and more simple state of the great orchidacean order." The geographical distribution shows that Cypripedium was more common in early times—to speak vaguely—and covered an area yet more extensive than now. And the process of extermination is still working, as with other primitive types.
Messrs. Veitch point out that although few genera of plants are scattered so widely over the earth as Cypripedium, the species have withdrawn to narrow areas, often isolated, and remote from their kindred. Some are rare to the degree that we may congratulate ourselves upon the chance which put a few specimens in safety under glass before it was too late, for they seem to have become extinct even in this generation. Messrs. Veitch give a few striking instances. All the plants of Cyp. Fairieanum known to exist have sprung from three or four casually imported in 1856. Two bits of Cyp. superbiens turned up among a consignment of Cyp. barbatum; none have been found since, and it is doubtful whether the species survives in its native home. Only three plants of Cyp. Marstersianium have been discovered. They reached Mr. Bull in a miscellaneous case of Cypripediums forwarded to him by the Director of the Botanic Gardens at Buitzenzorze, in Java; but that gentleman and his successors in office have been unable to find another plant. These three must have reached the Gardens by an accident—as they left it—presented perhaps by some Dutchman who had been travelling.
Cyp. purpuratum is almost extinct at Hong Kong, and is vanishing fast on the mainland. It is still found occasionally in the garden of a peasant, who, we are told, resolutely declines to sell his treasure. This may seem incredible to those who know the Chinaman, but Mr. Roebelin vouches for the fact; it is one more eccentricity to the credit of that people, who had quite enough already. Collectors expect to find a new habitat of Cyp. purpuratum in Formosa when they are allowed to explore that realm. Even our native Cyp. calceolus has almost disappeared; we get it now from Central Europe, but in several districts where it abounded the supply grows continually less. The same report comes from North America and Japan. Fortunate it is, but not surprising to the thoughtful observer, that this genus grows and multiplies with singular facility when its simple wants are supplied. There is no danger that a species which has been rescued from extinction will perish under human care.
This seems contradictory. How should a plant thrive better under artificial conditions than in the spot where Nature placed it? The reason lies in that archaic character of the Cypriped which Darwin pointed out. Its time has passed—Nature is improving it off the face of the earth. A gradual change of circumstances makes it more and more difficult for this primitive form of orchid to exist, and, conscious of the fate impending, it gratefully accepts our help.
One cause of extermination is easily grasped. Cypripeds have not the power of fertilizing themselves, except a single species, Cyp. Schlimii, which—accordingly, as we may say—is most difficult to import and establish; moreover, it flowers so freely that the seedlings are always weak. In all species the sexual apparatus is so constructed that it cannot be impregnated by accident, and few insects can perform the office. Dr. Hermann Muller studied Cyp. calceolus assiduously in this point of view. He observed only five species of insect which fertilize it. Cyp. calceolus has perfume and honey, but none of the tropical species offer those attractions. Their colour is not showy. The labellum proves to be rather a trap than a bait. Large insects which creep into it and duly bear away the pollen masses, are caught and held fast by that sticky substance when they try to escape through the lateral passages, which smaller insects are too weak to force their way through.
Natural hybrids occur so rarely, that their existence is commonly denied. The assertion is not quite exact; but when we consider the habits of the genus, it ceases to be extraordinary that Cypripeds rarely cross in their wild state. Different species of Cattleya, Odontoglots, and the rest live together on the same tree, side by side. But those others dwell apart in the great majority of cases, each species by itself, at a vast distance perhaps from its kindred. The reason for this state of things has been mentioned—natural laws have exterminated them in the spaces between, which are not so well fitted to maintain a doomed race.
Doubtless Cypripeds rarely fertilize—by comparison, that is, of course—in their native homes. The difficulty that insects find in performing that service has been mentioned. Mr. Godseff points out to me a reason far more curious and striking. When a bee displaces the pollen masses of a Cattleya, for instance, they cling to its head or thorax by means of a sticky substance attached to the pollen cases; so, on entering the next flower, it presents the pollen outwards to the stigmatic surface. But in the case of a Cypriped there is no such substance, the adhesive side of the pollen itself is turned outward, and it clings to any intruding substance. But this is the fertilizing part. Therefore, an insect which by chance displaces the pollen mass carries it off, as one may say, the wrong side up. On entering the next flower, it does not commonly present the surface necessary for impregnation, but a sterile globule which is the backing thereof. We may suppose that in the earlier age, when this genus flourished as the later forms of orchid do now, it enjoyed some means of fertilization which have vanished.
Under such disadvantages it is not to be expected that seed capsules would be often found upon imported Cypripeds. Messrs. Veitch state that they rarely observed one among the myriads of plants that have passed through their hands. With some species, however, it is not by any means so uncommon. When Messrs. Thompson, of Clovenfords, bought a quantity of the first Cyp. Spicerianum which came upon the market, they found a number of capsules, and sowed them, obtaining several hundred fine plants. Pods are often imported on Cyp. insigne full of good seed.
In the circumstances enumerated we have the explanation of an extraordinary fact. Hybrids or natural species of Cypripediums artificially raised are stronger than their parents, and they produce finer flowers. The reason is that they get abundance of food in captivity, and all things are made comfortable for them; whilst Nature, anxious to be rid of a form of plant no longer approved, starves and neglects them.
The same argument enables us to understand why Cypripeds lend themselves so readily to the hybridizer. Darwin taught us to expect that species which can rarely hope to secure a chance of reproduction will learn to make the process as easy and as sure as the conditions would admit—that none of those scarce opportunities may be lost. And so it proves. Orchidaceans are apt to declare that "everybody" is hybridizing Cypripeds nowadays. At least, so many persons have taken up this agreeable and interesting pursuit that science has lost count of the less striking results. Briefly, the first hybrid Cypripedium was raised by Dominy, in 1869, and named after Mr. Harris, who, as has been said, suggested the operation to him. Seden produced the next in 1874—Cyp. Sedeni from Cyp. Schlimii × Cyp. longiflorum; curious as the single instance yet noted in which seedlings turn out identical, whichever parent furnish the pollen-masses. In every other case they vary when the functions of the parents are exchanged.