47. Hooks rendered harmless till time of need.--There are a number of rather weedy-looking herbs, common to woods or low land, known as Avens, _Geum_. They are closely allied to cinquefoil, and all belong to the rose family. The slender stiles above the seed-like ovaries of some species of Avens are described as not jointed, but straight and feathery, well adapted, as we might suppose, to be scattered by the aid of wind; while others are spoken of as having, when young, stiles jointed and bent near the middle. In ripening, the lower part of the stile becomes much longer and stouter. When a whole bunch of pistils has drawn all the nourishment possible, or all that is needed, from the plant mother, the upper part of each stile drops off, leaving a sharp, stiff hook at the end. At this time each pistil loosens from the torus and can be easily removed, especially if some animal touch the hooks. To help in holding fast to animals, there are a number of slender hairs farther down the stile, which are liable to become more or less entangled in the animal's hair, fur, wool, or feathers. Even in the small number of plants here noticed, we have seen that scarcely any two of them agree in the details of their devices for securing transportation of seeds. I know of nothing else like the Geum we are now considering. When young and green, the tip of each hook is securely protected by a knob or bunch, with a little arm extending above, which effectually prevents the hook from catching on to anything; but, when the fruit is ripe, the projecting knob with its little attachment disappears. The figures make further description unnecessary. To keep the plow from cutting into the ground while going to or from the field, the farmer often places a wooden block, or "shoe," over the point and below the plow. Sometimes we have known persons to place knobs of brass or wood on the tips of the sharp horns of some of their most active or vicious cattle, to prevent them from hooking their associates or the persons having them in charge. Nature furnishes the points of the young fruits of some species of Avens with knobs, or shoes, for another purpose, to benefit the plants without reference to the likes or dislikes of animals. [Illustration: FIG. 56.--The pistil of Avens in three stages of its growth.]