The Romance of Plant Life / Interesting Descriptions of the Strange and Curious in the Plant World

by G. F. Scott Elliot

Amongst the wind-blown fruits and seeds there are cases in which entire plants are dragged out of the soil and hurried away by the wind, which rolls them over and over. They may be blown along for days together. The seeds drop out by the way. In this country one rarely sees anything of the sort, but in the Prairies of North America, when under cultivation, these tumble-weeds are a serious and expensive pest. Sometimes the farmers dig trenches to catch them, or they may put up fences against which the tumble-weeds become piled or heaped up until they blow over the top.

It is not very much use to give the names of these weeds, for they are mostly rare or not British species. Such tumble-weeds are generally nearly spherical in general form and have a short, rather weak, root which is easily torn out of the ground. In some grasses, such as "Old Witch," a well-known pest of the United States, the grass-stalk, with many flowers on it, is pulled out of its sheath and blown away.

But it is more usual for the fruits or seeds themselves to break off the parent plant, and to be carried away by the wind. To this end we find the most extraordinary changes. Although the flower may droop from its stalk, the latter becomes upright and grows quite a considerable length when the seed or fruit is dispatched on its wanderings. This will raise the fruit or seed as high as possible above the surrounding grasses.

Then in some cases the fruit opens to allow the seed to escape. Small holes appear in it, or the fruit splits. As the dry, elastic, withered stalk swings to and fro in the wind, the seeds are swung out of these openings, and starting with a certain momentum the wind will carry them often to a surprising distance from their parents. In wet or rainy weather these holes or slits generally close together, and no seeds are sent forth on their travels. The little holes in the top of a poppy-head by which the seeds are swung out have little flaps, which close over and shut them up in wet weather.

Some plants make a sort of catapult to sling or hurl their fruits. Kerner von Marilaun was the first to describe some of these curious arrangements. He had brought home some fruits of Dorycnium herbaceum and laid them on his writing-table. "Next day as I sat reading near the table, one of the seeds of the Dorycnium was suddenly jerked with great violence into my face." Some of the neatest catapult fruits are those of Teucrium flavum. (There is a British species, the Woodsage, but it has not got the same arrangement.) When the petals have fallen off, the four small fruits are left inside the cup-like sepals; the flower-stalk when dry is very elastic, and if an animal touches the sepals it swings violently and shoots out one of the fruits. But that is by no means the whole of the process: there are hairs arranged spirally in the throat of the sepals, and these give a spin or twirling motion like that of a rifle-bullet to the fruit. The fruit also flies out of the sepals in a line of flight which is inclined at an angle of about forty-five degrees to the horizon; at this angle, as is well known, the trajectory or distance travelled will be the greatest possible.

But by far the best way to understand these questions is to try with some common weeds in the country towards the end of summer or beginning of autumn. If either the Cow Parsnip or wild Angelica, or Myrrhis, be gathered and kept till it is quite dry, then if you take it by the stalk and swing it to the full extent of the arms the fruits fly off to fifteen (or more) feet away. Every part is elastic—not only the main stalk, but the thin separate stalks of the flowers and also the delicate piece by which each half-fruit is attached. The half-fruits themselves are also so made that they are of exactly the right shape to take a long flight.

Ever since the days of Icarus, one of the unsatisfied ambitions of mankind has been to fly like a bird, to "soar into the empyrean," and to be no longer chained to the earth's surface.

It is a very curious study, that of the many and diverse inventions, almost always useless and very often fatal, by which men have endeavoured to solve this problem. Every one of these can be paralleled amongst the many neat contrivances of wind-borne fruits and seeds. The principle of the "parachute," which is more or less like an umbrella, is found in both fruits and seeds. One of the most beautiful is the Dandelion fruit, where a series of the most exquisite branched hairs springs from the top of the slender shaft which carries the little hard fruit. Most of the Composite or Dandelion order have, however, more of the "shuttlecock" idea. There is a row or crown of stiff and spreading or feathery hairs.