The pistil matures a little later than the stamens do-. It is long and narrow, and is divided at its summit into two arms, which at first are raised upright and closely pressed together (Fig. 4). In this position each little arm covers the sticky inner surface of the other, so that no grain of pollen can be dropped between them, and only these inner surfaces are receptive to the pollen's vitalizing touch. On the outer surface of the pistil, especially towards its tip, are short, scattered hairs pointing upward. As the growth of the pistil carries it up through the anther-ring, these hairs collect the pollen which remains clinging to the outside of the pistil after its full growth is attained. Now the pistil projects far above the anther-ring and corolla, so that the pollen which covers its surface can scarcely fail to be brushed off upon the body of any visiting insect (Fig. 4, a). And the dandelion is a general favorite, almost certain of a run of company. The honey is very abundant, and rises high in the little tubes, and this feast is offered at a time when nectar is scarce in the chill and windy world. Ninety-three species of insect have been observed by Muller paying their attentions to the dandelion.
Fig. 4. - Florets and fruits of the dandelion.
After a while, when most of the home-made pollen has been carried away by insects the arms of the pistil bend downward, till they are in the position of the crosspieces of the letter T (Fig. 4, b). Now their sticky or stigmatic surfaces are extended to touch the insect as he flits by, pollen freighted. But if no winged wayfarer comes along, the arms of the "pistil bend downward still further, and as the flower grows older they curl backward like the horns of a ram (Fig. 4, c).
Coiled up in this way the sticky inner surface of each little arm is brought into contact at several points with its outer surface. And on the outer surface there will probably be pollen-grains brought from other florets by the same enterprising insects which carried off the golden store of this one. So the Dandelion pistils help to gather pollen for themselves, and can supplement the good offices of flies and bees.
The very first dandelions are apt to appear in the bleak days of early spring, which are not tempting to insect-rovers, so that they may receive no visitors at all. In that case the little florets make shift to do without them. The arms of the pistil when they curve downward will come into contact with the sweeping hairs still covered with the pollen from the anther-tube. And this will be turned to account to meet the needs of the case, for the dandelion floret can, at a pinch, set its seed by means of its own pollen.
Many flowers, especially many spring flowers, droop, and thus save their treasures of pollen and honey from being injured by rain and dew. But the dandelion florets stare straight at the sky, and they come at a very rainy season. If Nature took no preventive measures, the gold and silver tubes would speedily resolve themselves into little water-jars; pollen and honey would be spoiled or washed away altogether, and the insect when he called would get nothing but disappointment. But the little blossoms are so constituted that during rainy weather and at night they close completely, and thus all their treasures are preserved. Before the dew begins to fall the dandelions in the grass seem to vanish. The florets in each yellow head are sleeping, and tucked into bed, too, for a ring of little leaves (botanists call it an involucre) which surrounds the mass of tiny blossoms has bent over so as to enclose and enfold them.
The dandelions seem to have turned to buds again, and in their green outer covering they are undistinguishable from the surrounding grass and leaves. Their night's rest is a long one. They rarely awaken before seven o'clock, even on a sunshiny morning, and they close about five in the evening.
An involucre is present in all the members of the great composite family. It serves as a public calyx, filling for the floral cooperative society many duties which are filled by the calyces of solitary blossoms.
It shelters the florets in their infancy, it helps to guard their nectar from crawling thieves, and, in many species, it screens their pollen from the rain, and encloses and cradles them at night. The calyces thus "thrown out of their jobs," are placed in a position somewhat akin to that of a community of work-people, whose many individual tasks have been taken up and synthetized by some piece of labor-saving machinery.
They must learn some new way of making themselves useful, or they will perish - following a general law of all disused organs.
So throughout the great family of composite flowers we find the calyx of the floret so modified as to help in the great work of plant distribution (Fig. 5). In the bur-marigold it is converted into barbed prongs, which fasten onto the passer-by, and force him to aid the plans of the parent plant for placing its offspring in life. In the dandelion and in some of its cousins the calyx is so modified that by means of it the wind is forced to act as a sower. Below each dandelion floret is a little oval, white body, which is the baby fruit, and around each floret a circle of silky hairs, the reminiscence of an ancestral calyx. After the yellow corolla has withered away, these hairs remain at the post of duty, for they have still a task to fulfil in the plant's economy. They are to aid the wind in distributing the little dry fruits - not seeds - which develop after the disappearance of the yellow florets.
Groundsel calyx, altered into down. (From the Vegetable World).
Bur-marigold calyx, altered into prongs. (From Yearbook, Department of Agriculture, 1896).
Orange hawkweed calyx, altered into bristles. (From Yearbook, Department of Agriculture, 1896).
Fig. 5. - Some altered calyces of composite flowers.
For the word "fruit" to the public at large suggests a juicy edible, with a rich or delicate color, and with, generally, a pleasant taste. But "fruit" to the botanist means whatever comes as the normal result of the fertilization of a flower. It may be a tiny brown object unadorned, desiccated, and quite destitute of gastronomic interest. The little freights of the dandelion blow-aways being each the developed and ripened seed-case or "ovary" of a fertilized floret, are fruits.
The feathery balls of ripe dandelion fruits are frequently in requisition among children anxious "to find out what time it is." Hence it is, perhaps, that dandelions have been nicknamed "peasant's-clocks" and "blow-balls." The shaven and shorn aspect of the remnant, after the winged fruits have departed, has suggested two other local English names for the flower, "monk's-head" and "priest's-crown".
The tip of each young fruit elongates into a slender beak, raising the tuft of hairs, which are laid together, side by side, like the ribs of a closed umbrella (Fig. 4, d). But when the fruit is ripe the hairs bend downward and assume the position of the ribs of an open umbrella (Fig. 4, e). Thus the fruits become provided with a silken parachute apiece, and are ready to fly on the wings of the wind and sow themselves far and wide. They will not drop beside the parent plant into soil which has been drained of the substances which are particularly necessary and wholesome to dandelions. They will emigrate, flying on gauzy wings to "fresh woods and pastures new".
Each fruit, let us notice, is roughened with little thorny projections; so if the "blow-away" ends its flight against any moving object with a rough surface, the coat of an animal, for instance, or the clothing of a traveller, the attached fruit will catch and cling, and thus be carried still further from its starting point.
These methods of pushing the family fortunes have proved so successful in the past that the dandelion is now distributed as a weed in all civilized parts of the world.
So Nature has cared for the gamin of the fields. How could the queenliest orchid be better cared for by the most scientific gardener of them all?