Forms of Roots
1. Simple fibrous. 2. Branched fibrous. 3. Tap root. 4. Tuberous root.
Roots are capable of absorbing liquids only, and all fertile soils contain more or less soluble mineral matter which is dissolved by the moisture present. This matter is absorbed mainly by the minute root-hairs—outgrowths of the superficial cells—which are to be found on the rootlets or small branches that are given off from the main descending axis.
The principal forms of roots occurring in our flowering plants are:—
1. The simple fibrous root, consisting of unbranched fibres such as we see in the Bulbous Buttercup and the Common Daisy.
2. The branched fibrous root, as that of the Chickweed and Grasses.
3. The tap root, which is thick above and tapers downwards, like the roots of the Dandelion, Carrot and Wild Parsnip.
4. The tuberous root, common among the Orchids.
5. The creeping root, possessed by some Grasses in addition to their fibrous roots.
Besides these common forms there are roots of a somewhat exceptional character, such as the aerial roots or suckers which grow from the stem of the Ivy and serve to support the plant; and the roots of the Mistletoe, which, instead of penetrating the soil, force their way into the substance of certain trees, from which they derive the necessary nourishment.