Illustrated Glossary
In order to distinguish one kind of tree from another, it is necessary to learn the major characteristics which the forest trees of Illinois may possess. Illustrated below are several of the most commonly encountered characteristics of leaves and twigs. A thorough understanding of these structures will insure a quicker and more accurate identification.
On the pages following the illustrated glossary are keys to the trees of Illinois. A key is a botanical device which enables the user, through proper selection of a series of choices, to identify a specimen at hand. Separate keys are provided for trees during the spring, summer, and autumn seasons and during the winter season. Begin at the first pair of number 1’s, choose the statement that best fits the unknown specimen, and then go to the next pair of statements beneath. Continue this same procedure until the name of the plant is reached.
LEAF FORMS AND ARRANGEMENT SIMPLE PINNATELY COMPOUND PALMATELY COMPOUND DOUBLY PINNATELY COMPOUND OPPOSITE ALTERNATE WHORLED LEAF SHAPES LANCEOLATE OBLANCEOLATE OBLONG ELLIPTICAL OVATE OBOVATE
WINTER TWIG CHARACTERS
WINTER TWIG CHARACTERS BUD SCALE TERMINAL BUD LATERAL BUD LEAF SCAR LENTICELS BUNDLE TRACES {LEAF LAYERS} UPPER EPIDERMIS PALISADE LAYER RIBS AND VEINS SPONGY LAYER STOMA LOWER EPIDERMIS LEAF TIPS ACUTE OBTUSE LONG-TAPERING LEAF EDGES PINNATELY LOBED WAVY TOOTHED DOUBLY TOOTHED SMOOTH LEAF BASES HEART-SHAPED TRUNCATE ASYMMETRICAL ROUNDED TAPERING