1. FLOWERING PLANTS The fact of outstanding importance to everyone who really looks at most plants is that part of them are above ground and part below. This simple observation carries with it the recognition of a fundamental difference of plant structure, namely roots and stem. Most plants bear obvious leaves, and at some time in their life flowers, inevitably followed by fruits and seeds. The ideally perfect plant would consist, then, of root, stem, leaves, flowers, fruit, and seed. These are subject to many changes of form, sometimes they are put to strange uses, and occasionally one or two may be lacking, as the stem is apparently from many violets, and leaves from some cactus and from the Tjemoro tree of Malaya. In fact, so varied are the different forms of these common attributes of most plants, so important are these differences of structure that no right understanding of plant life can be had without examining each in some detail. THE ROOT The obvious purpose of the roots of plants is to serve as an anchorage or holdfast. Their other and equally important function is to secure food for the plant, a process that will be described in the part devoted to Plant Behavior. Certain plants bear no roots and attach themselves to the roots of other plants in which case they literally steal their food, as does the mistletoe and some others. Roots are of various kinds, depending upon the soil in which they grow and upon the kind of plant to which they are attached. In the case of _annuals_, which live only one year, as does the purslane, and _biennials_, which live only two years, as does the fringed gentian, the roots are mostly fibrous (Figure 1) and apt to be only slightly under the surface. In _perennials_, which live many years, such as the dandelion, the root is deeper and forms what is known as a _taproot_ (Figure 2). In shrubs and trees they are harder, woodier, and often penetrate to great depths. [Illustration: FIG. 1.--FIBROUS ROOTS As illustrated by the common garden nasturtium.] If we examine the roots of a tree, we find a large part of them are woody, often as thick as the smaller branches, and it is only toward their extremities that they branch out into the multitude of rootlets [Illustration: FIG. 2.--TAP ROOT OF CARROT A store of food for the second year.]