Fig. 43. Much-branched stem of the Oak.
Each kind of tree has a way of branching which is characteristic of its species, so that even without leaves or flowers a woodman can tell what a tree is. This one can learn by practice in the woods, but to begin with it is rather difficult. Without going into detail, however, we may notice great family differences, such as exist between a larch or a Christmas-tree and an oak. In the first two there is one straight main trunk, with side branches at very regular intervals (see fig. 44), and in the oak the main thick trunk soon bears several large branches nearly equalling the main stem; these divide again and again in a rather irregular fashion (see fig. 43).
Fig. 44. The Larch, showing its strong central trunk and more delicate side branches.
In many of the smaller plants the stems are not strong enough to stand up against the wind, and they simply lie along the ground or support themselves by growing among other plants, such, for example, as the common Stellaria, where the stem is very delicate indeed (see fig. 45). Then again, if you pull up a large water-lily, you will notice how soft and limp the long leaf-stalks are. They cannot support themselves at all in the air, though they were upright in the water. This is because the stalks get their support from the water which allows them to float up, so that the plant does not build a strong stem. You will find that plants are very economical in their use of strengthening material, and never waste it where it is not wanted. If you remember this, and then study all the stems you can, and note when and where they are strengthened, you will find what good and economical architects plants are.
Fig. 45. Delicate stem of the Stellaria, partly lying on the ground.