Trees, in some form or another, have been around for a lot longer than we have. The first plants to meet the general definition of trees were probably the giant tree ferns which are now rare, but were common enough during the Carboniferous Era to form the coal and oil deposits we now use.
Most trees, as we commonly think of them, fall into one of two groups which we can call coniferous and broad-leaved. Most, but not all, conifers produce their seeds in woody cones, exceptions being the junipers and yews, and don't really have what we think of as flowers. Most, but not all, broadleaf's produce their seeds in more fleshy fruits, and have flowers, even though many of the flowers are quite small. The conifers evolved before the broadleafs; flowers didn't appear in the world until many millions of years after the appearance of trees.
The easiest way to tell the broadleafs from the conifers, for either a blind or a sighted person, is by the shape of the leaves. For the most part, leaves of conifers and smaller and narrower than the leaves of broadleafs, thence the name 'broadleaf'. In North America, most conifers retain their leaves during the winter. Exceptions are the Larches and the Baldcypress. Many, but not all, broadleafs lose their leaves in the winter. The chlorophyll in the leaves is what gives them their green color, so when that is no longer produced, the other colors that were present all along come through and the leaves change color. A layer forms between the leaf stem and the twig to protect the tree from moisture loss, and then the leaves fall.
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A Concise Guide To Trees.
Acak*Identifies The Most Common Trees, With A Picture,Quick Reference Box And Informative Text For Each. Illustrated Throughout With Superb Color Photographs. Detailed Introduction Provides Infomation On How To Identify Trees, Their Distribution And The...
