Tree Identification Terminology

Terminology - Leaf, Twig, and Fruit Characteristics
Used in Tree Identification http://www.clemson.edu/extfor/publications/bul117/characteristics.htm

Familiarization with the following diagrams and terms will make the leaf key and tree descriptions easier to understand and use.  Information provided here is divided into the following topics:

general terms leaf forms anatomy of a twig

anatomy of broad leaves leaf arrangement leaf margins

leaf tipsleaf basestypes of fruits

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GENERAL TERMS

leaf — a lateral outgrowth from the stem whose primary function is the manufacturing of foodtwig -- a young woody stem to which leaves and buds are attached branch -- a thicker, older woody stem to which twigs are attached trunk -- the main vertical stem of a tree fruit — the seed-bearing portion of a plant deciduous — trees on which all leaves fall at the end of every season of growth evergreen — trees on which leaves remain attached for more than one year

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LEAF FORMS
conifer — a tree with needle or scale-like leaves
fascicle — a dense cluster of leaves or needles (far right)
broadleaf — a tree with wide, flat leaves

BROADLEAVES

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ANATOMY OF A TWIG

terminal bud — a bud that is at the tip of a stem or branch
bud scale — a small modified leaf on the outside of a bud

lateral bud — a bud that is situated along the sides of a branch and not at the tip

lenticel — a corky spot on the bark which originally permitted air to enter the twig

leaf scar — the scar left on a twig when a leaf falls

bud scale scar — the scar left on a twig when a bud scale falls

bundle trace — dot-like scars within a leaf scar, representing the broken ends of ducts which led to the leaf stalk

node — the place on a twig where a leaf is attached

internode — the part of a twig between two nodes
pith — central, usually soft portion of a twig,  chambered piths are divided into empty compartments by cross partitions
thorns and spines (not pictured) — sharp-pointed, rigid structures arising from the twig or leaf

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ANATOMY OF BROAD LEAVES

apex — the tip or distal end of a leaf margin — the outer edge of a leaf blade leaflet — an individual blade of a compound leaf midrib — the central or main vein of a leaf rachis — the midrib of a compound leaf blade (lamina) — the flat or expanded part of a leaf petiole — stalk of a leaf axilary bud — lateral bud located at the base of a leaf petiole

compound leaf — a type of leaf that has three or more leaflets attached to a common stalkpalmately compound — veins or lobes of a leaf radiating from a central point pinnately compound — arrangement of leaflets attached laterally along the rachis of a compound leaf

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LEAF ARRANGEMENT

opposite — leaves occurring in pairs at the nodes alternate — leaves arranged singly at intervals along the stems whorled — leaves occurring three or more at a single node

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LEAF MARGINS

entire — a leaf margin that is smooth without teeth or lobes

undulate — a leaf margin that is wavy

serrate — a leaf margin that has pointed teeth that are directed upward

doubly serrate — a serrate leaf margin where the primary teeth support another set of teeth

crenate — a leaf margin that has rounded teeth

lobed — a segmented leaf having pointed or rounded extensions separated by sinuses that do not extend more than halfway to the midrib
sinus — the space or indentation between the lobes of a leaf blade

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LEAF TIPS acute — slightly pointed acuminate — sharply pointed bristle-tipped — sharply pointed tip truncate — squared or abruptly cut off obtuse — rounded

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LEAF BASES cuneate — wedge-shaped obtuse — rounded cordate — heart-shaped truncate — squared or abruptly cut off oblique — asymmetrical, unequally sided

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TYPES OF FRUITS

berry — a simple, fleshy fruit, with seeds embedded in a pulpy mass (persimmon)

drupe — a one-seeded, fleshy fruit with the seed inclosed in a stony wall (cherry, sugarberry, holly)

capsule — a dry fruit which splits open into two or more parts at maturity (sourwood)

legume — a dry fruit with two seams in the outer wall (black locust)

nut — a hard-shelled, dry fruit, sometimes with a outer covering or husk (hickory, oak acorn, black walnut)

dehiscent — the opening by slits or valves of an outer fruit covering

indehiscent — an outer fruit covering that does not open by slits or valves

pome — a fleshy fruit, with seeds incased by a papery wall (apple)

nutlet — a small nut

samara — a winged, one-cell, one-seeded, dry fruit (elm; double samara — maple)

multiple — a fruit formed from several flowers into a single structure having a common axis

multiple of capsules -- sweetgum
multiple of follicles — magnolia
multiple of samaras — yellow-poplar, ash
multiple of nutlets — sycamore, birch

follicle — a dry fruit with one seam in the outer wall

pendant — hanging or drooping

globular — spherical

bracts -- small leaf or leaf-like structures beneath a flower or flower cluster that sometimes become protectors of the fruit