Botanists seem to have invented a special term for every conceivable structure or arrangement of parts, no matter how small the size or slight the difference! The number of technical terms used in RainforestPlants has been kept mercifully small. Really! As you continue with your study of plants, your botanical vocabulary will undoubtedly continue to expand. Until then, mastery of the following terms and those contained in “How to Examine Plant” is a reasonable goal for the beginning tropical biologist.
Flowering plants have traditionally been divided into two large classes, the monocots and dicots. The names are derived from the numbers of “seed leaves” or cotyledons exhibited by newly emerged seedlings with monocots having one and dicots two. Monocots tend to have strap-like leaves with parallel venation. In the tropics they may also have large banana-like leaves and/or pinnate venation. Grasses, Palms, Arums, and Orchids are large monocot families. Dicots tend to have broad leaves with complex netted venation. All trees, except for the palms, belong in this group. The most recent classifications maintain these two classes, but recognize a third group, “Magnoliids,” formerly considered to be dicots. The separation is based upon closer analysis of morphological traits that are intermediate between the two older classes, despite having large leaves that clearly resemble dicots. The decision is also supported by DNA analysis. The “Magnoliids” are well represented in the tropics by the Annonaceae, Myristicaceae, Lauraceae, and Piperaceae families.