THE OAK FAMILY The fifty kinds of- oak trees that are native to America are about evenly divided on the two sides of the Rocky Mountains. No Western oaks are found in the Eastern states, and none of our Eastern kinds grows wild on the other side of the mountains. The backbone of the con tinent is a bar that neither group has been able to pass.
To know fifty different kinds of oaks by sight, so as to call each one by its right name, is not an easy task; and yet it is not so difficult as it at first might seem. To begin with, any tree we meet, which bears acorns, we at once recognise as an oak. By this one sign, we are able to set this great family apart from every other tree. As soon as they are old enough, all oaks bear acorns. If a tree which we suspect to be an oak has no acorn to show us, on or under the tree, a little close looking will usually find some acorn cups still hanging on, or lying where they fell upon the ground.
The leaves of oaks are distinctive. In general, they are all simple, and their outline is oval. The borders are variously cut by deep or shallow bays, between sharp points or rounding finger like lobes. They are leathery in texture, com pared with leaves of most trees. After a little practice, we learn to recognise oak leaves, no matter how variously cut their borders may be.
In spring the flowers of oaks come out with the leaves. A fringe of catkins at the base of the new shoot is composed of pollen-bearing Rowers. In the angles of the new leaves farther up the stem, we shall find the little acorn flowers, usually in twos. This is the flower arrangement of all the oaks; staminate and pistillate flowers on the new shoots, separate and very different from each other, but always close together, and always both kinds on each tree. The fringe of catkins falls as soon as the pollen is shed. Little, red, forked tongues are thrust out by the pistil late flowers to catch the golden dust when it is flying through the air, and thus to set seed. All
through the summer, the little acorns are grow ing. We can find them in their tiny cups in the angles of the leaves.
In the autumn the acorns are ripe, and falling. Some trees will show acorns of two sizes, half grown ones on the new shoots, and full-sized ones on the bare twigs, just back of the new shoots.
This peculiarity divides the oak family into two great groups. One group is composed of trees which have light-coloured bark, bear a crop every year, and in winter are bare of fruit. This is known as the White Oak Group. Its leaves have rounded margin lobes which do not end in sharp points, as many of the lobes of oak leaves do.
All of the oaks whose leaves have pointed, spiny lobes on their margin belong to the Black Oak Group. The bark of these trees is usually dark-coloured. The acorns require two years of growth. For this reason, there are half-grown acorns on the tree all winter, waiting for the second summer to bring them to maturity. Every autumn the acorns which are ripe are found on the twigs just back of the leafy shoots, which grew during the past summer. These acorns have completed their second year of growth.
When we hear any one speak of annual-fruited and biennial-fruited oaks, we know that the White Oak and Black Oak Groups are meant. If you see an oak tree whose leaves are cut into sharp pointed lobes, you will find acorns of two sizes on its twigs. If you look across the fence and see a pale-barked oak with finger-lobed leaves, and not a spiny point on their mar gins, you will know that acorns of but one size will be found. Fix these three points in mind. Then study all the oak trees you can find.
Trees of the White Oak Group have : i. Rounded lobes on their leaf margins.
2. Acorns ripe in a single season.
3. Pale-coloured bark.
Trees of the Black Oak Group have : I. Spiny-pointed lobes on their leaves.
2. Acorns requiring two seasons to ripen.
3. Dark-coloured bark