Angiosperms vs. Gymnosperms
Trees are scientifically divided into two major categories: angiosperms and gymnosperms.
Angiosperms are flowering plants and their seeds are encased in a protective ovary. This division contains the larger number of species can be further subdivided into dicots and monocots. Dicots
have two seed leaf structures and include many broadleaf trees such as the elm, maple and oak. Monocots have one seed leaf structure and include species such as the palm.
Gymnosperms, on the other hand, do not produce flowers. Their seeds have structures such as cones, rather than a protective ovary. Conifers (needle-leaf trees) are a major group of gymnosperms.
Deciduous vs. Coniferous
Trees can also be divided into deciduous and coniferous categories.
Deciduous trees are also known as broadleaf trees because the leaves are generally larger and wider than those of conifers. The larger leaf size means a greater surface area for photosynthesis, but it also mean the
leaf is too fragile to withstand winter conditions. Therefore, most deciduous trees drop their leaves in autumn.
Coniferous trees keep their leaves throughout the year, shedding only the oldest leaves. Usually these leaves are lower down on the tree and do not receive as much sunlight as newly developed leaves higher up. Some
of the best-known members of the conifer family are pines, spruces, firs, and hemlocks. The cones of the conifers are its flowers.