In early spring there appear in dry, sterile places, often on the slope of a railway embankment, in locations where few other plants can even exist, myriads of brownish yellow stems four to twelve inches high, of the same size from top to bottom, and each topped with a curious, cone-like head. These are the fertile stems of the Field Horsetail. There is something very mushroom-like in the rapidity with which these fleshy stems mature when once they have started to develop, and the likeness is increased by the fact that there is no green about them and also that they multiply by means of spores instead of flowers and seeds.
Each fertile stem is decorated at intervals with several slightly bulging rings of slender, dark, sharp-pointed scales that are united at the base and point upward. The blossom, which is not at all a blossom to a botanist, is a cone at the very top of the odd-looking stem, and is made up of row after row of tiny disks set around the central stalk. Before the cone is ripe there extends back from the edge of each disk a row of little sacs stuffed so full of green spores that they look united like a row of tiny green ridges. The uppermost disks discharge their spores first and the empty sacs are whitish and hang dishevelled around the disks.
Field Horsetail. Equisetum arvense
These spores are produced in great abundance, and at the proper time the slightest jar will shake them out in clouds. By shaking a ripe stem over a piece of white paper apparently a green powder is obtained which, under the microscope, proves to be many tiny green balls, each with four spiral bands wound about it. These spirals uncoil and throw the spore, giving it a movement as of something alive. The motor power in these living springs is the evaporation of the moisture in them, as they prepare to drift away with the wind, bearing on their wings the hope of the plant. After the spores are scattered the fertile stems wither and disappear. At the same time the sterile stems begin to appear springing from the small buds at the top of the rootstock near the point where the fertile stem arises. These finally develop into erect stems from ten to eighteen inches high and bearing ring after ring of green fringe. This fringe of angular branchlets gives the plant a bushy appearance, in which it is not difficult to fancy a likeness to the tail of a horse.
The Horsetail is not a flowering plant, but its stems are one of the first signs of returning spring, and its early and striking appearance gives it an honored place among springtime vegetation.