Springtime and Other Essays. Sir Francis Darwin
syringa (Philadelphus) is another foreigner, which early shows autumnal tints—yellowing on 27th September. Then follow some native trees: the beech and birch both turning yellow on 1st October, and being followed by the maple on 7th October. I like the motherliness of the half-grown beech, who refuses to drop her dead leaves in autumn, hoping (as I imagine) that they will shelter her tender leaves in the chilly springtime. The older beeches give up this anxious care, and doubtless laugh among themselves over the fussiness of young mothers. They forget, no doubt, that in the scrub at the feet of their own boles the habit persists.
With regard to the fall of leaves, the sycamore begins to lose them 2nd October; birch and cherry, 8th October; maple and walnut, 12th October; aspen, 13th October; beech and elder, 13th October; ash, 14th October; Lombardy poplar and Virginian creeper, 18th October; honeysuckle, 22nd October; hazel, 26th October; elm, 28th October; whitethorn, 30th October; plane, 3rd November. Judging by a single observation of Blomefield, the larch is the last performer in the drama of autumn. It turns yellow on 8th November, and its leaves fall 15th November.
Blomefield [3] records that on 29th November the trees are “everywhere stript of leaves,” so that some sort of colour-drama has been in progress from the middle of September to the end of November. It may be objected that what has been said of autumn is but a catalogue of names and dates. And this is true enough; but when we realise the glory of autumnal decadence, it seems (however baldly recounted) to be a fitting prelude to the great outbreak of new life—green leaves and bright flowers that spring gives us.
In Blomefield’s “Calendar” the difference between December and January is exaggerated. For, as it stands, it suggests that plants know that a new year has begun, and all burst into flower on 1st January. But that careful naturalist points out [4a] “all those phenomena which are referred to 1st January, as the earliest date, may be considered as occasionally showing themselves in December of the previous year.”
The plants that bloom in winter, i.e. December and January, are few enough. The Christmas rose gives us its white or pink flowers in December, and the primrose may flower in the first days of January—indeed, I seem to remember it in Kent before Christmas, but I will not answer for it. According to Blomefield, the honour of being the first plant to awake must be given to the honeysuckle (Lonicera caprifolium), which unfolds its leaves between 1st January and 22nd February, i.e. on 21st January on the average. This bold behaviour is all the more to its credit since it is said by Hooker [4b] to be a naturalised plant.
Then follow in order the flowers of furze, hazel, winter aconite (Eranthis), hellebore (H. fœtidus), daisy, and snowdrop; so that the winter flowers make a most pleasant show, and tempt us to raise January to the rank of the first month of springtime—but we must allow the credit to be justly due to winter. In winter, too, we must be grateful to the ivy of the bare hedgerows shining in the sun, its leaves glistening like the simple jewels of a savage.
With February, we are agreed that spring comes in, but it is a springtime that keeps something of the graveness of winter: though, when the silver sunshine begins to be decorated with the singing of birds, we must call it spring.
In February, too, the roads are no longer edged with dead white grass, but show the fresh green of wayside plants—cow-weed, nettle, dock, and cleavers.
The trees still stand naked, their leaf-buds waiting for a better season. I like to think of wintering plants not as being asleep, but rather as silent. They sing with all their green tongues when spring releases them from the cupboards (which we call buds) where she has kept them safe.
The service-tree is a hardy creature, for its buds are naked and unprotected, like Pampas Indians who are proud of sleeping uncovered, and of seeing, as they rise, their forms outlined in the hoar-frost. I have only recently noticed the purple tint of alder-buds; [5] and I am reminded of the character in Cranford, who needs Tennyson’s words “Black as ash-buds in March” to teach him the fact. Some trees show their flowers early. For instance, the hanging tassels of the hazel, from which the dusty pollen can be shaken out, and the tiny red tufts which are all the female flower has to show. The alder, too, has a brave crowd of lambs’ tails. The elm should flower about the middle of March, and its pink stamens make a pleasant sight. These plants are called anemophilous—that is, wind-loving, as though grateful to the wind for carrying their pollen without payment. I can imagine that the plants employing insects to carry pollen from one to another feel superior to the wind-fertilised clan. We may fancy the duckweed (speaking of the pine) to say: “Of course, he is very big and of an ancient family, but for that very reason he is primitive in his habits. I know he boasts that he employs the winds of heaven as marriage priests, but we are served by the animal kingdom in our unions—and that, you must allow, is something to be proud of.” [6] But duckweeds grow so crowded together that they are probably fertilised, to a great extent, by contact with their neighbours, without aid from the animal kingdom. We may also imagine the duckweed reproving the pine for his extravagance in the matter of pollen production. This, however, is necessary, because the pollen being sown broadcast by the wind, it is a matter of chance whether or not a grain reaches the stigma of its own species, and the chance of its doing so is clearly increased by multiplying the number of pollen-grains produced. Enormous quantities of the precious dust are wasted by this prodigality. We read of pollen swept from the decks of ships, or coating with a yellow scum lakes hidden among Tyrolean pinewoods. Pollen is so largely dispersed in the air that it has been supposed to be a cause of hay-fever.
Blackley found, by means of a sticky plate, which could be exposed and covered again, when raised high in the air on a kite, that pollen is dispersed to considerable altitudes. Wherever vegetable débris collects, pollen-grains may be found. Kerner found them, together with wind-borne seeds and scales of butterflies’ wings, sticking to the ice in remote Alpine glaciers.
Another characteristic of wind-borne pollen is dryness or dustiness; the grains are smooth, not sculptured like the pollen meant to be carried by insects; nor are they sticky or oily, as is often the case with entomophilous pollen. The advantage to the plan is obvious; the grains, from the absence of the burr-like quality, or of any other kind of adhesiveness, do not tend to hold together in clumps, but separate easily from one another, and float all the more easily. [7]
Several adaptations are found to favour the dispersal of the pollen. Wind-fertilised plants are generally tall; thus in Europe, at least, the commonest representatives of the class are shrubs or trees—witness the fir-trees, yew, juniper, oak, hazel, birch. And where the plants are lowly—e.g., grasses and sedges, and the plantains—the flowers are more or less raised up on the haulm. An exception must be made of some water-plants—e.g., the Potamogetons, where the flower-stalk is but slightly raised above the surface.
Wind-fertilised plants have many characteristics which favour the dispersal of the pollen. The grasses have long pendent stamens, and versatile anthers, from which the pollen is easily shaken out by the wind. There are, of course, exceptions to these generalisations. Such plants as Hippuris and Salicornia have no particular adaptations: the filaments are short, and the plants themselves are not of sufficient height to be able to scatter forth their pollen efficiently by the mere bending of their stems. The need for exposure to the wind is shown in another way—namely, by the habit of the Cupuliferæ (oak, hazel, etc.), of flowering before the leaves appear; this not only favours the start of the pollen on its flight, but is probably still more useful in increasing its chance of reaching the stigma.
If the pollen is exposed to the wind it will be liable to be wetted and injured. Catkins—such as those of the walnut or hazel—give some protection to the pollen, since the stamens are covered in by tile-like scales; but where—as in the grasses and plantains—the anthers hang far out of the flowers, the pollen is easily injured. Some of the cereals protect themselves against injury by means of a remarkably rapid growth of the filaments; thus the anthers remain hidden within the flowers until the last moment, and, under the influence of a warm sunny morning, rapidly protrude themselves. If the scales of the flower are artificially separated, the growth can be produced by warmth and moisture; Askenasy describes a trick of country children, who put ears of rye in their mouths and thus produce a miraculous growth of stamens. The growth or rapid