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  Guide to the Common Trees of Pennsylvania

Trees | Glossary | Visual Guide | Leaf Parts, Types, & Position

Axil - The upper angle where a leaf stalks joins the stem or a smaller stem joins a larger one.
Alternate - One leaf attached at each node. See opposite and whorled.
Capsule - A dry fruit which contains more than one seed and splits open when ripe.
Catkin - A compound bloom consisting of scaly bracts and flowers usually of one sex.
Deciduous - Refers to trees which drop their leaves in autumn. Compare to evergreen.
Downy - With very short and weak soft hairs.
Drupe - A type of fruit having a single seed enclosed in a hard layer and that is covered with soft, often juicy flesh, as in cherries and peaches.
Evergreen - A plant that retains green leaves throughout the year. Life span of an individual leaf can be 2-15 years.
Leaflet - A leaf-like portions of the blade of a compound leaf. There is no bud in the axil of its petiole.
Leaf Scar - The impression in a twig at the point where a leaf was attached.
Lenticel - A pore in the bark of young trunks and branches through which air passes to interior cells.
Lobe - A division or projecting part of the blade of a leaf.
Opposite - Two leaves attached at each node. See alternate and whorled.
Pedicel - The stalk of a flower or inflorescence.
Petiole - The stalk attaching a leaf blade to the stem.
Pith - The spongy material in the center of twigs and young trunks.
Sessile - Refers to a plant part having its base attached directly to the stem without an intervening stalk.
Stalked - Refers to a leaf or flower having a length of petiole or pedicel between its base and the stem. See sessile.
Witches'-broom - Abnormal brushy growth of small branches caused by an infection.
Whorled - Three of more leaves or other parts attached to a stem at the same point.

Select a Tree from a menu below, or download the Visual Guide

Needle-Shaped or Linear


Wide & Flat: Opposite Arrangement

Wide and Flat: Alternate Arrangement

Information courtesy of:
PA Department of Conservation & Natural Resources


Whitetailed Deer
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