Popular Science Monthly/Volume 55/July 1899/Unusual Forms in Plants
|UNUSUAL FORMS IN PLANTS.|
By BYRON D. HALSTED.
THE unexpected is apt to occur. Along with the regularity in living things, which we call "uniformity of Nature," there is so strong a tendency to vary that one almost expects to find a turn in the avenues of life sooner or later, and that gradual or sudden, as the case may be. We will not stop to discuss the open question of whether we are possessed by an inherent quality of variation, or as creatures of circumstances, subject to the controlling forces of our environment.
Yesterday while looking at a row of seedling peaches, all from the same lot of pits, one of the miniature trees was found to be bronze or copper colored throughout. This set me to thinking. Here was a "sport," as it is termed, and if I take good care of the abnormity, bud it into common stock, etc., the landscape architects and ornamental gardeners may thank me for the novelty that will please their wealthy patrons.
Leaving aside the abnormal as met with in the animal world, for much of it is more painful than otherwise to contemplate, let us glance at some of the unusual things occurring among plants.
One first thinks of some strange forms in leaf, and if the eyes are opened to them they may be met with upon every hand. The "four-leaf" clover is lucky perhaps only because the finder is sharper-eyed than others, and stands a brighter chance of seeing success as it crouches almost invisible in the wild grass, the tilled field, or wherever the eyes may be set to find it.
The child who brings me the oddities of vegetable forms is knowing in the normals of his class of curiosities, or else he would not see the novelties from the finding and exhibiting of which he gains so much pleasure. The person who is familiar with the striking beauty of the cardinal flower (Lobelia cardinalis) is the one who rejoices at the variations that may occur in the tints of the bright corolla. His delight would reach a high pitch should the conspicuous spikes be found upon dry ground, and not by the bank of some stream half hidden by the overhanging grass. But should the wandering plant display white flowers, then an albino of a most interesting kind has been met with, and some reason for it is sought in the unusual locality. Only a few days ago a white variation of the Lobelia syphilitica, cousin to the cardinal, was seen by the writer treasured in the Botanical Garden at Cambridge, Mass., and it called to mind the rage for pink water lilies, that twenty years ago were only met with wild in ponds at Plymouth, Mass. I asked an expert recently if there was any call for the pink or "Plymouth" lilies, and he informed me that the fad had died out with the transplanting and widespread culture of the pink "sports" of the nymphæa ponds.
Abnormal colors in flowers are among the most common freaks in wild plants, and none are more frequent than the albinos. One could fill a page with instances of this sort. Some of our most common weeds, as the moth mullein (Verbascum blattaria), have a large percentage of the plants with white blossoms, and the patches of the white interspersed with the normal yellow-flowered plants in poorly kept meadows and neglected land has led the writer to gather seed of each to test the truth of the opinion that the white strain may be transmitted to the offspring, but the proof is not yet at hand.
The writer knows where there is a patch of the hound's tongue (Echinospermum) with a good sprinkling of plants producing white corollas instead of the normal deep maroon. The two colors make a good subject for students who are gaining an elementary knowledge of the stability of species, and the range of striking variations that must be allowed for them,
Next to the albinos the instances where the floral parts approach leaves in size and color are the most common. A few weeks ago while passing through a field once devoted to corn, but now overgrown with weeds, and therefore of special interest to a botanist, my eyes fell upon a daisy plant all the heads of which were with olive-green ray flowers instead of the ordinary pure white ones. These rays were smaller than the normal and quite inclined to roll, as shown in Fig. 1, and form quills, as seen in some of the fancy chrysanthemums. By the way, our common field daisy is a genuine chrysanthemum and that which is produced in one species under the guiding, fostering hand of the skilled gardener was here shadowed forth in the field of waste land.
A week or so later, while going through a similar field in an adjoining county to the one where the daisy freak was found, I came upon nearly the same thing as seen in the heads of the "black-eyed Susan," or cone flower (Rudbeckia hirta L.). Here were the two leading weedy daisies, the white and the yellow, the former coming
Fig. 1.—Green and Normal Oxeye Daisy Heads.
to our fields from the East and across the sea, while the latter, as a native of our Western prairies, journeys to make a home here and help to compensate by its pestiferous presence for the vile weeds that have gone West with the advance of civilization. Both of these daisies revealed that tendency in them to vary in their floral structures that if made use of by the floriculturist might result in forms and colors as attractive and profitable as met with in their cousins the chrysanthemums of the Orient.
Perhaps the season which we have had, with its excess of moisture and superheat, has made the abnormal forms more abundant than usual. The even current of life has been met by counter streams, so to say, and the channels were broken down. In walking through a meadow in early June it was a common thing to find the spikes of the narrow-leaved plantain (Plantago lanceolata L.) branched and compounded into curious shapes. Some of the normal and malformed spikes are shown in Fig. 2.
Fig. 2.—Malformed heads of Plantago Lanceolata.
As a tailpiece to this portion of the subject it is a pleasure to introduce a freak among the native orchards, as shown in Fig. 3. A word of explanation is needed of the normal form of the lady's slipper here shown. As found in the moist woods, the plant above ground consists of two leaves and a single pink and strange-looking blossom terminating the stalk. This is the rule, and it has been strictly adhered to, so far as the writer knows, for centuries with a single exception, and that exception is the one here presented. It is as remarkable as a double-headed dog, and as difficult of explanation as the twin thumb.
Perhaps the best way is to make no attempt to account for the freak, and leave the subject open for those who have a gift of insight into the secrets of the abnormal and the unexpected. Other species of cypripediums regularly bear more than one flower; this one may have done so in former ages, and here is the link that binds our pretty unifloral species to its remote and possibly extinct ancestor. On the other hand, a double-flowered form is possibly in embryo, and before the next century closes the Cypripedium acaule Ait. may need to have its description changed so as to embrace two flowers.
The influence of moisture, heat, and light is very great upon vegetation, and one only needs to observe the same species of plant as grown in a moist, shady place, as compared with the ones that are located in the full sun where the soil is dry. Size and shape of parts, and even their color and the surface, are different, and this all leads us up to the cultivated plants where variation is the rule and constancy the exception.
Among wild plants where similar surroundings obtain for all members of the species the albino is noted, and any replacement of stamens by petals, as in the wild buttercup, is the rare exception. But the cultivated plants have led a charmed life, and we scarcely wonder that the plants in the bed of sweet peas or gladiolus, canna or dahlia, are as diverse in form and color as the pieces in a crazy-bedquilt. Man, with all his ingenuity and skill, has been at work molding the plant clay made plastic by generations of special culture.
In one sense the greenhouse, the garden, orchard, and even the cultivated field are all dealing with monstrosities. The well-filled horticultural hall at a State or county fair is a vast collection of unnatural curiosities—that is, they do not occur in Nature, but are truly the creations of the mind of man as worked out along lines of vegetable physiology and stimulated plant production. For dinner this very day the writer ate a slice of a modern watermelon. What a triumph of horticultural art was exhibited in that giant fruit, each seed of which was filled with the accumulated tendencies of a generation of high breeding! There was represented the influence of soil and selection, of crossing and of culture, until the wild melon, which none of us sees or cares to see, is gone and a special creation takes its place, with its great demands upon any one who would attempt to grow it to perfection.
The art of breeding might possibly have deprived it of seeds had there been some other convenient method for propagation, as is true of many of our tree fruits, the navel orange being a striking example. Along with the absence of seeds and the presence of fine flavor there is truly a monstrous form, in that one orange is within and at the "navel" end of the other.
Should we glance at some of our garden vegetables, as, for example, the cabbages in their various races, every one will be struck with the strangeness, to say the least, of the forms produced. In contrast with the head of the true cabbage, where leaf is folded upon leaf until a mass of metamorphosed foliage as large as a half bushel is produced, there is the cauliflower, with the edible substance stored in a fleshy inflorescence that has lost its normal function and become truly monstrous. Were it not so tender and delicate a food we might be disposed to smile at the absurdity of the whole thing, or at the kohl-rabi, with its turniplike bulb in the stem just above the surface of the ground. It is certainly a plastic species that will give such diverse and fantastic forms—so far from the wild state, and for that reason so useful to mail.
In the same manner a comparison of our orchard fruits with the forms from which they came would lead to the thought that man has made them to his liking, and not for service to the plant species. They are abnormal, judged by all standards in Nature; monstrous in size and in many cases have lost their essential structure as seed-producing organs.
Coming to the ornamental grounds, the disguises are largely swept away, and there is but little hope of judging what the original plants may have been from which have descended the favorites of the flower bed and the conservatory. Species have been split into a thousand and one varieties, each with its peculiarities and each with the potency for greater deviation. Where shall we cast the line and land an example? The rose show of June is only surpassed by the chrysanthemum exhibition in autumn. There must be the new sorts brought out each year, whether the fancy be for a special shade or color or a striking new shape of bud or form of bloom. Would you realize what a novelty means to those in the craft who watch a group of carnation growers as they hang over the exhibit of a "new" rival, and consider all the merits and defects of the candidate for a certificate?
All the beauties of the flower garden are so familiar to us that it is not expected that they will be considered unnatural. If the hydrangea makes a panicle larger than it can bear, man helps it out with a string or stake, for by overdoing it is not undone any more than is the coddled peach tree held up at fruiting time by a dozen poles, or the forced lily with a weak back supported upright by an artificial green stem at church on Easter morning.
But even here there are monstrosities in the true sense. The asparagus or sweet potato stem occasionally broadens out into a ribbon, and it passes as an abnormity. The same thing takes place in the flower cluster of cockscomb (Celosia cristata), and if it failed to produce a strange fan-shaped and highly colored and crested top the owner would complain that her seed had given her
Fig. 4.—Monstrous Blossoms of Foxglove.
only an inferior pigweed, and therefore not come true to name. The attractiveness of the cockscomb resides in the strange habit the plant has of broadening the upper end of the flower stalk out into a form that is truly monstrous. And this brings me to speak of a form that attracted my attention during the present season, samples of which are shown in Fig. 4.
The striking feature of the specimens of foxglove (Digitalis purpurea) under consideration is the production of an enormous somewhat bell-shaped flower at the extremity of the long racemose inflorescence, and at a time when only a few of the lowermost blossoms upon the stem have opened. The normal digitalis flower has a large pendant purple corolla much spotted upon the middle lobe of the larger and lower lip. On the other hand, the truly monstrous flowers, two to three inches across, are borne terminally and are quite uniformly bell-shaped, with the lobes from twelve to fourteen and spotted evenly over all the surface. The four stamens of the normal flower have increased to twelve in three examined and to thirteen in another. These stamens are normal in size and situated upon the corolla tube, except that there is no indication of their being in long and short pairs.
The single pistil is many times enlarged in the monstrous blossom—in one instance two thirds of an inch in diameter for the ovary. Within the outer ovarian wall there was a circle of five petaloid pistils, some showing the placentæ and ovules intermixed with the pink and purplish petaloid expansions.
Within the circle above mentioned there was a second pistil, tipped like the original with petal-like lobes instead of a stigma. The column was found so closely built up that the parts would not separate, and a cross-section was made through it, which showed that the pistil had a greenish central stalk around which the ovarian cavities were scattered quite irregularly, all bearing numerous ovules. In the flowers with twelve stamens there were four tips to the stigma, and the eight cavities were to be distinguished in the ovary, although they were not arranged in any regular order and not uniform in size. In short, the transections of these resembled the seed cavities seen in a slice of a large tomato of the "trophy" or "ponderosa" type.
The florists' catalogues advertise in a few instances this "Digitalis monstrosa" and it is presumed that the specimens from which the engraving was made were from a packet of this "strain" of seed. As but a small percentage of the plants in the bed examined were monstrous, letters were addressed to some German growers of the seed, with questions as to this commercial monstrosity. One reply contained the statement that the form known as "monstrosa" had been in the market about ten years, and that about fifty per cent of the plants produce the strange terminal flowers. Another correspondent recalls the form in question as having been catalogued for more than forty years, and that it is described in a work upon gardening published in 1859, in which it states that the seed of this variety must only be gathered from the capsules of the monstrous flowers in order to preserve the abnormity. Concerning this last my correspondent said that it is all the same whether the seed is taken from the capsules of monstrous flowers or from the whole spike. Seed taken in this way will give from twenty-five to thirty-five per cent of the monstrous flowers, but the ratio varies from year to year.
There are some advantages to the floriculturist in the monstrous form as the first bloom in it is uppermost and very conspicuous, while in the normal form the blooms appear from below upward, and the drooping tip of the spike is the last to produce flowers. The case in hand is a remarkable deviation from the type in many ways, but most interesting of all is the fact that floriculturists have by selection developed a variety that, in a packet of a hundred seeds, is quite certain to give some plants of the type "monstrosa," which it bears as its trade name.