Page:Popular Science Monthly Volume 51.djvu/658

642 this fact the plant is sometimes recognized as the "Arizona candle."

Just beneath the epidermis and alternating with the spiny ribs are strong ligneous fascicles. These fascicles are of the same number as the ribs, and serve as a support for the soft parenchyma tissue which constitutes the great bulk of the plant.

The fascicles are not unlike huge fish poles, twenty to forty feet long and from one to three inches in diameter, flattened radially as relates to their position of growth. This woody portion endures long after the other parts of the plant have decayed and is popularly known as the skeleton. During the growth of



the plant the fascicles increase in size each year by the addition of a woody layer to their outer surface, in the same manner as the oak and maple add their annual layers. The layers of growth forming the older fascicles are very close together, sometimes a hundred being crowded into less than an inch of space.

This portion of the plant is of great value to both Indians and Mexicans, as it not only serves as firewood but is extensively utilized in both fence and house building. When cut to requisite length it makes excellent pickets, and throughout its entire range the dirt roofs of the adobe houses are supported by the long, strong fascicles.

We find by counting the layers of growth that many of the