A Text book of Tropical Agriculture

five parts, namely, the root, the stem, the leaves, the flowers and the fruit. There are some plants, it is true, that have one or more of these parts wanting, but it is unnecessary to consider them in this work, for the tropical agriculturist is concerned mostly with the ordinary flowering plants. The ROOT, which is called the descending axis of the plant, varies very much in its character. In the grasses and other plants, the roots consist of many fibres spreading out in the soil in all directions ; some of them, indeed, are much longer than the stem, as in the case of the maize?the roots of which have been traced to the length of fourteen feet. Other roots, called tap-roots, send a thick prolongation of the main axis straight down into the soil, and give off small fibres at intervals ; the best example of this is the carrot, but Functions of coffee and cacao also possess tap-roots. Roots have two important functions : firstly, they fix the plant into the soil, or to the substance on which it grows ; and, secondly, they take up nourishment for the plant to live and thrive on. At their ends all roots become very small and tender, and give Root hairs, off minute, hair-like prolongations, called appropriately root- hairs. The extremity of a root is covered by a cap of stronger tissue so as to protect the growing point, and to enable it to make its way into the soil. The root-hairs apply themselves to the particles of the soil, and by means of the acid ...