Popular Science Monthly/Volume 52/November 1897/Burs and Beggar's-Ticks

BURS AND BEGGAR'S-TICKS.

By SPENCER TROTTER,

PROFESSOR OF BIOLOGY IN SWARTHMORE COLLEGE, PENNSYLVANIA.

MY setter comes out of the underwoods, after one of his incursive rambles, garnished with strings of green "stickers" and with harsh, brown burs clinging tenaciously to the long, feathery hairs of his tail and about his legs and ears. I have kept in the narrow path to avoid these pests of the autumn woods only to find that they have laid fast hold upon my clothes when by some unwitting step I brushed against the border tangle. In picking them off I notice their curious forms and the fact that they are not all alike. Here are some slender darts that seem to hold by barbed heads; there a row of flattened pods clinging by their whole surface; while numberless tiny brown burs are gathered in groups or scattered promiscuously about trouser legs and coat skirt.

It is strange how an interest is suddenly awakened about the most commonplace objects in life. We move for years among old, familiar things without giving them a passing thought, when all at once some subtle spell is cast about them, and they become vested with a charming interest. I have tramped many times through autumn woods and picked off the "stickers" with no good will, but to-day they strike me as more than "stickers." I have discovered an old friend among them. Withered and brown, I should scarcely have recognized the friend of my springtime rambles but for a certain odor of the roots and a sprig of young green leaves by the side of the old, dry stalk. It all comes back now—sweet cicely of the spring woods with its umbels of white blossoms and that sweet, anise like smell of its roots. To discover an old friend in a strange guise is enough in itself to whet one's interest, and I have curiosity to know how sweet cicely fares in the undertime of the year. All through the woods I find the dry, leafless stalks of the plant adorned with slender, black seed-pods that cling in pairs to the delicate pedicels of the umbel clusters. Under a magnifying PSM V52 D081 Sweet cicely myrrhis odorata.png lens each pod reveals a structure of wonderful design, the sole purpose of which is to fasten on to any object that may brush past. To this intent it is furnished with delicate hooks, arranged in parallel lines along its sides, lying close against the pod and pointing back from its free end. The free end of the pod tapers into a slender style armed with the same hook like structures, so that whatever part is touched it will be sure to cling fast.

Another umbelwort, the fruit of which catches on to the clothes in our autumn woodland walks, is sanicle or black snakeroot. We come upon it in the undergrowth of hillsides and in the dry woods of the uplands with its small, brown burs bunched in clusters on the ends of the branching stem. It grows scarcely higher than one's knees, and in the tangled mass of brown and green is often passed unnoticed. Each little bur presents an array of minute hooked bristles, set closely together, and forming a most effective means for attachment to the hairy covering of animals.

The various species of Desmodium, or tick trefoil of the pulse tribe, are among the most persistent "stickers" of the October woods. The flattened, several-lobed pods are more familiar to us as clinging in detached lobes to our clothes after coming out of the woods than when hanging from the branching tops of the slender, wandlike plants. It is seldom that a complete pod is found, for the deeply cut joints of the one-seeded lobes need only a gentle pull to break them. The lobes have a raspy feel, and a pocket lens shows their flat sides to be thickly covered with minute, curling hairs, and few "stickers" are harder to pull off than those of the desmodiums, since they cling closely by their whole surface to any woolly substance.

A group of "stickers" that frequently adorn the wanderer through autumn woods are those of the bedstraw or cleavers of the genus Galium. In some of the species the low, trailing stems and their leafy branches are roughened PSM V52 D082 Galum plant.png with small, hooked bristles, while in others, as in the common cleavers, or robin-run-the-hedge, the fruit also is thus armed and adhesive. Circæa, the enchanter's nightshade, that grows so abundantly in the depths of cool, moist woods, contributes a large share to the motley collection of "stickers," its small, burlike fruit being covered with tiny, hooked prickles. So in the species of comfrey, or hound's tongue, the nutlets are rough-coated with an armament of short barbs and hooks that fasten themselves to the wool and hair, and are very troublesome to sheep that stray into the copses along the pasture side. The fruit of one species, familiarly known as "beggar's lice," is one of the most annoying pests of the woods, and Gray, at the end of his technical description of the plant, calls it "a common and vile weed."

Among the Compositæ there are comparatively few plants which effect their dispersal in this parasitelike way, most of the forms developing the characteristic downy structures known as pappus, like the dandelion and the thistle, that float their seeds away on the wings of the wind. Some species, however, like the bur-marigolds, have fallen into the parasitic mode of dispersal, and these are mostly plants of the low, tangled thickets along streams and in swampy places. The many-flowered heads of the bur-marigold ripen in the PSM V52 D083 Desmodium.png fall into numerous flattened seedlike bodies, or achenia, each one of which is crowned with two or more stiff, needlelike, and barbed awns. Few "stickers" are more annoying than these "beggar's-ticks" of the bur-marigold. There is not a patch of low tangle that is not full of them, and one can scarcely pass by such places without bearing away a closely clinging horde of the pests. In the drier woods of the uplands a familiar species of bur-marigold is abundant, with longer and more slender achenia, which are known as "Spanish needles."

Among the larger burs that gather PSM V52 D083 Bur marigold.png on us in the fall are those of two composite plants—the burdock and the cocklebur. They are both weeds of waste places, coarse and ill-looking, springing up in rank abundance about pigpens, barnyard fences, and the dump heaps of open lots. The redeeming virtue of the burdock is its purple flower heads crowning the bristly green involucres, which in childhood days were plucked to make "buz-baskets." The larger and coarser cocklebur, with its armament of strong hooks, is another of Dr. Gray's "vile weeds," wrapping itself inextricably among the hair and wool of the dog or sheep that unwittingly strays into its domain.

The fruit is the vehicle of the seed, and in each seed lies hidden the germ of a new plant. To spread itself as far and wide over the earth as its environing conditions will allow is the aim of every plant. In some the fruit has developed into an edible berry, and the hard-coated seeds pass uninjured through the bodies of animals, and are scattered long distances away from the parent plants. In many forms it is fashioned for sailing in air currents; in some, like the cocoanut, with its tough, buoyant husk, to be floated on the waves and washed by the tides and ocean currents to distant shores. Every plant tends to hold back this dispersive effort until its seeds have matured. As this is accomplished PSM V52 D084 Cocklebur.png the ovary ripens into the fruit, of a form and fashion after its kind. The green color, that served to protect it when ripening amid the mass of foliage, changes to the conspicuous reds and yellows that catch the eye of a wandering animal—and so its part is played. Among these burs and "stickers" of our autumn woodlands we see but another means for securing this end. The wandering deer or bear, the hunter following its trail through the undergrowth, the fox, skunk, raccoon, and such lesser wood folk, each serves a turn in bearing away these bristly fruits. How well it has been accomplished is seen in the wide dispersal of these plants. A striking fact in evidence of this is the relatively large number that have come from the shores of Europe as uninvited guests. Circæa, the burdock, cocklebur, several species of cleavers, and a species of comfrey have thus become naturalized in our country, and it is not improbable that several of our native species have found their way to the Old World by catching fast to some passing vagrant, who later took ship and landed with the burs still clinging to his clothes.

Reproduction and dispersal are the two great aims in the life of every plant and animal. All else is but the means, the mere contrivances to gain the best advantage in the accomplishment of these ultimate efforts. Every species, every individual exists by virtue of having striven to attain these ends. In the structure of each one is the record of the attainment, partial or complete, as the case may be. And each man and woman of us is toiling in his or her way toward the same goal, unconscious of that something within us, greater than ourselves, that "guides us, blindfold but safe, from one age on to another." The burs and "stickers" that cling so persistently to our clothes are but a part of the same great effort. It is the only way sweet cicely, desmodium, the bur-marigold, and their kin have of traveling through the woods, and so on from forest to forest, from swamp tangle to swamp tangle. They live their lives as truly as a man lives his, with equally as good a purpose that is equally as well attained. Each embodies those essential qualities of living that the great teacher discerned when he bade men "consider the lilies of the field."