Seed vessel

“ The use of the Seed-vessel is to protect the seeds till ripe, and then in some way or other to promote their dispersion, either scattering them by its elastic power, or serving for the food of animals in whose dung the seeds vegetate, or promoting the same end by various other mens. ”

“ But if we look a little more closely at the sunken and floating seeds, we find that in the same genus there are species with seeds or seed-vessels that sink and species with those that float. We look again and then perceive that the same general principle is true of different species of the same genus growing inland and at the coast. We learn now that as a rule when a genus possesses both littoral and inland species, the seeds or fruits of the former float in sea-water for a long time, whilst those of the latter have little or no floating power. ”

“ The Effect of Sea-water Immersion on the Germinating Capacity of Seeds and Seed-vessels Berkeley, Darwin, Martins, and others, long ago established the capacity of seeds to germinate after prolonged immersion in sea-water. The reader will find a resumé of their results in the appendix to Mr Hemsley’s volume on the Botany of the Challenger Expedition. The subject is well illustrated in the original papers of those authors, and in my later papers on the flora of Keeling Atoll, and on the seed-drift of the Thames. ”

“ The dregs must be calcined to extract a salt from them. 6. Pour the distilled dew imbued with this extracted salt upon the seed, and then close the vessel with pounded glass and with borax. It must then be kept for a month in a hot bed of horse-dung. 7. Take out the vessel and you will see the seed at the bottom become like jelly; the spirit will float on the top like a thin skin of divers colours; between the skin and the thick substance at the bottom you will see a kind of greenish dew. ”

“ The planter follows with seed in a tin box, or any small vessel having a broad bottom, and taking a small pinch between the thumb and forefinger he gives a slight scratch with the remaining fingers of the same hand, and dropping in about half a dozen seed covers them half an inch deep with a sweep of the hand, and packs the earth by a gentle pat with the open palm to keep the moisture in the ground and thus promote the vegetation of the seed. ”

“ If we were to include in our list the shore-plants of temperate regions that possess seeds or fruits capable of floating in sea-water for long periods, and of afterwards germinating, the total for the whole world would not, I imagine, reach 200. We cannot here concern ourselves with those purely river-side plants that contribute their buoyant seeds and seed-vessels to river-drift, since there is no evidence indicating that river-side plants are effectively dispersed by the currents unless they also frequent the estuary and the coast-swamp ”

“ The seed-vessels of these plants in their wild state are thin, stringy, and tough in comparison with the garden varieties which have been produced by watching for unusual development of the seed-vessels, and selecting the seed from the most fleshy. ”

“ It usually makes very little difference whether sea-water or fresh water is employed, since in my numerous experiments there were but few exceptions to the general rule that seeds or seed-vessels that sink in fresh water sink also in sea-water. ”

“ All the seed vessels should be pricked off in order to secure the best results, as much of the strength of the plant goes to them if allowed to remain. One can afford to be very liberal in gathering the flowers, for the more liberally they are picked off, the more rapidly buds form and develop. ”

“ It is remarkable that in selecting plants with buoyant seeds or seed-vessels for a station at the coast Nature has generally ignored those with very small seeds. When such small seeded plants, as Sesuvium portulacastrum, occur on the beach, the seeds have as a rule no buoyancy. ”

“ This is a capital scheme, for when the pods are dry and unfurled, they silently indicate to the slightest breath of air that they are ready for a flight, and it doesn't take much to carry them for a long distance. As an active boy delights to venture again and again over thin ice on a shallow pond in the pasture, half fearing, yet half hoping, that he may become a hero by breaking through and escaping, so likewise many of these seeds and seed-like fruits spread themselves out, as if to tempt the wind to come along and attack them. ”

“ This also facilitates the floating and transportation of the nut in the sea. When the breakers have flung it upon rocks or broken reefs, here its fibrous covering helps it cling until the young roots grow and anchor it securely.
Thus endlessly during all the seasons of the year the trees are sowing their ripened seed and sending them forth, variously equipped, blindly to seek a place in which they may live, perpetuate the species, and extend the forest.
It is well that nature sows seeds like a spendthrift. ”

“ So we plant seeds in rows on our dam-wall, and pull one up daily to see how it goes with them. Alladeen buried her wonderful stone, and a golden palace sprang up at her feet. We do far more. We put a brown seed in the earth, and a living thing starts out, starts upward—why, no more than Alladeen can we say—starts upward, and does not desist till it is higher than our heads, sparkling with dew in the early morning, glittering with yellow blossoms, shaking brown seeds with little embryo souls on to the ground. ”

“ In most of my sea-water experiments in England the immersion had a very marked influence, not in causing premature germination and destroying the germinating capacity, as often happens with the floating seeds of Convolvulaceæ and Leguminosæ, especially in the tropics, but in postponing without injury to the seed the process of reproducing the plant. Such seeds or fruits when placed in fresh water after many months of flotation in sea-water germinated very freely in a few days, whilst those left in the sea-water under precisely the same conditions remained unchanged. ”

“ Only the head and six prolegs of the occupant ever emerge from its case. Dragging its house along upon the plant, it attaches the open mouth of the sack close to the green seed-pod, after which the shell is gnawed through at the point of contact, and the young seeds devoured at pleasure, when a new journey is made to the next capsule, and thus until the maturity of the larva. ”

“ In fresh-water experiments, in nearly all cases, the seeds ultimately germinate in the water, and this is the usual cause of the close of the experiment. In an ordinary collection of floating seed drift from a pond or river, germination will go on for years at each successive spring, the postponement of germination being a very striking feature with a fair proportion of seeds in river and pond-drift. ”

“ The lighter seeds, as those of pines and maples, are transported chiefly by wind and water; the heavier, as acorns and nuts, by animals.
In all the pines, a very thin membrane, in appearance much like an insect's wing, grows over and around the seed, and independent of it, while the latter is being developed within its base. Indeed this is often perfectly developed, though the seed is abortive; nature being, you would say, more sure to provide the means of transporting the seed, than to provide the seed to be transported. ”

“ Then a breeze tears off a few pods and they fall on the snow, which has filled up all the crevices in the grass and between the dead leaves and rubbish. Each half-pod, freighted with every other seed, is admirably constructed; like an ice boat, it has a sail always spread to the breeze. In this way there is often nothing to hinder some of the seeds from going a mile or two in a few minutes, now and then striking some object which jars off a seed or two. The seeds are very hard, and no doubt purposely so, that they may not be eaten by insects or birds ”

“ The existence of spiral vessels, particularly in such quantity, and, as far as can be determined in the dried specimens, unaccompanied by other vessels, is a structure at least very unusual in the integuments of a seed or caryopsis, in which they are very seldom at all visible, and have never, I believe, been observed in such abundance as in this genus, in all whose species they are equally obvious. ”

“ This seed is of a rather triangular shape, thick and heavy at the part by which it grows from the cone, and terminating in a broad membranous fan or sail, which, when the seeds are shaken out by the wind, enables them to sail obliquely through the air to great distances. ”

“ Meadows and pastures, especially where the land is not fertile, abound in weeds that require two years or more to produce seeds, such as narrow-leaved dock, bitter dock, bull thistle, carrot, teasel, two kinds of mulleins, night-flowering catchfly, evening primrose, several kinds of fleabane, ox-eye daisy, orange hawkweed, two or three kinds of plantain, Canada thistle, hound's tongue, stick seed, sow thistle, horse nettle, buttercups, toad flax, silvery cinquefoil, and many more, not excluding some annuals, like crab-grass, tickle grass, pigeon grasses. ”

“ When the rivers break up, the seeds are carried down stream, and perhaps left to grow on dry land after the water has retired. Most of the commonest plants, the seeds of which are usually transported by water, are insignificant in appearance and without common names, or with names that are not well understood. ”

“ In this way seeds of water plantain, sedges, grasses, rushes, docks, arrowhead, pondweeds, duckweed, cat-tail flag, bur reed, bladderwort, water crowfoot, and many others are transported from one pond, lake, or stream, to another. In some cases enough of a living plant may be detached and carried away to keep on growing. Darwin found on the feet of some birds six and three-quarter ounces of mud, in which were five hundred and thirty-seven seeds that germinated. ”

“ By following up the path of inquiry that is concerned with the flotation of seeds and seedvessels, we are guided into other fields of research that give promise of interesting discoveries in connection with plant-life. We are led in the first place to consider the question of utility, and to ask whether the buoyancy of the seed or fruit has been a matter of moment in the history of the species. Nature is ever engaged in telling off the plants to their various stations. ”

“ In sheltered regions the seeds of trees may fall, sprout and take root close to their parent trees. As a rule, the wind plays a prominent part in distributing seed in every section of the country. Pine and fir seeds are equipped with wings like those of a bird or an airplane. They enable the seeds to fly long distances on the wind before they drop to the ground and are covered with leaves. Maple seeds fly by means of double-winged sails which carry them far afield before they settle. ”

“ While some seeds are destroyed by passing through the digestive tract of animals many are not harmed in the least. From over two hundred and fifty different kinds of plant seeds fed to a variety of birds over 80 per cent germinated perfectly after passing through their digestive tracts. And perhaps the most remarkable case is the seed of a pondweed said to be incapable of germination until it has passed through a bird. This plant grows in fresh water ponds in great quantities and is much eaten by wild ducks. From the stomach of one bird over three hundred such seeds were recovered. ”

“ The large growing varieties being so long of coming to produce seed, that many plantations are cut down before they reach this maturity, the small growing and weakly varieties, known by early and extreme seeding, have been continually selected as reproductive stock, from the ease and conveniency with which their seed could be procured; and the husks of several kinds of these invariably kiln-dried25, in order that the seeds might be the more easily extracted! ”

“ It is plain that should these seeds simply fall to the ground, plants of a single species would soon become so crowded in a small area that the earth could not support them. Consequently various means are furnished different plants for the dispersion of their seeds. A great number, like the thistles, milkweeds and dandelions, have plume-like parachutes provided for each seed, so they can float away on the breeze to new fields; those that have their seeds embedded in fruit are entrusted to birds to be carried where fate wills it ”

“ A few are introduced to grow for ornament or food, and afterwards spread as weeds. A number have been shipped to distant lands in the earth of ballast, which is often unloaded and reloaded at wharves where freight is changed. They are carried along the highway, strung along the towpath of canals, or are carried in the trucks or in the cars of railroads. They are imported and exported around the world in fleeces of wool. They float down irrigating ditches from farm to farm, and with the water are well distributed. ”

“ By the broad-cast system of culture, the land is often sown in bad tilth, the seed is always scattered at random, and sometimes by very unskilful hands. In drilling, the ground must be in good order; and the seed set in trenches regularly drawn, all being nearly of an equal depth, which is adapted to the nature of each particular kind of seed. ”

“ The highest latitude to which a tree, or any other kind of plant, reproducing by seed, {357} naturally extends, depending on the ripening of the seed, and also on the power of occupancy, is however different from that where it will grow, when ripe seeds are procured from the coldest place where they ripen, and all the competitors removed; and under the system of shelter belts, hardy pine nurses, and seeds from the nearest place where they ripen, we have no doubt that oaks may be extended to a colder situation than Nature herself would have placed them in. ”