LEAF TERMINOLOGY

THE GOAL OF THIS

PRESENTATION IS TO HELP

VISITORS IDENTIFY THE

FLOWERING PLANTS THEY SEE

WHILE HIKING IN THE

WESTCHESTER WILDERNESS

WALK.

TO LEARN HOW TO IDENTIFY

FLOWERING PLANTS YOU WILL

NEED TO LEARN BASIC LEAF

MORPHOLOGY.

IF YOU WISH TO LEARN MORE

ABOUT BOTANICAL TERMS, VISIT

OUR GLOSSAY LINKED FROM THE

FLOWERING PLANTS HOME PAGE

OR, FOR MORE TECHNICAL

TERMINOLOGY, STUDY THE

MANUAL OF LEAF ARCHITECTURE.

A HAND LENS IS ONE OF THE MOST IMPORTANT

TOOLS OF A BOTANIST.

MANY OF THE PLANT CHARACTERS CAN ONLY

BE OBSERVED WELL WITH A HAND LENS.

BASIC LEAF TERMINOLOGY

THE POSITION AND COMPLEXITY

OF PLANT LEAVES ARE TWO OF

THE FIRST CHARACTERS TO LOOK

AT WHEN IDENTIFYING PLANTS.

ALL SPECIES OF MAPLE IN THE

PRESERVE HAVE SIMPLE LEAVES.

IN ADDITION THE LEAVES ARE

ATTACHED OPPOSITE TO ONE

ANOTHER ON THE STEM.

THE ONLY OTHER TREE GENUS

WITH OPPOSITE, SIMPLE LEAVES IS

CORNUS (DOGWOOD) BUT THAT

GENUS HAS ENTIRE, NOT LOBED,

LEAF BLADES.

Drawing by B. Angell

BLACK OAK GROUP WITH POINTED OR BRISTLED LOBES

Lobing may be variable within a species and sometimes even

within an individual tree

WHITE OAK GROUP WITH

ROUNDED LOBES (BRISTLES ABSENT)

ODDLY (LEFT) AND EVENLY (RIGHT) PINNATE LEAVES

ODDLY PINNATE

LEAVES ARE ALSO

CALLED

IMPARIPINNATE

LEAVES AND EVENLY

PINNATE LEAVES ARE

ALSO CALLED

PARIPINNATE LEAVES.

BIPINNATE LEAF

The entire structure is one leaf,

i.e., everything above the bud

is the leaf. There are no buds

In the axils of the primary and

secondary leaflets.

Always look for buds in the

leaf axils to help you determine

if a leaf is simple or compound.

There are no species with

bipinnately compound leaves

in the WLT Preserve.

Photo by C. Gracie

From Hickey, 1973

LEAF SHAPE,

BASE, APEX, AND

MARGIN CHARACTERS

ARE USED

TO DESCRIBE

FLOWERING PLANTS.

ALTHOUGH THESE

CHARACTERS ARE

USEFUL THEY ARE

VARIABLE AND DIFFICULT

TO DESCRIBE.

SOME SPECIES ARE EASY

TO IDENTIFY WHILE

OTHERS ARE DIFFICULT!

LEAF FEATURES

TILIA AMERICANA IS EASY TO IDENTIFY BASED ON LEAF CHARACTERS

FEATURES OF LEAF

VENATION USED

IN PLANT

CLASSIFICATION

From Hickey, 1973

VENATION ORDERS

There are venation orders greater than tertiary veins but they are not

visible without magnification (see glossary for terms).

FEATURES OF LEAF

VENATION USED

IN PLANT

CLASSIFICATION

From Hickey, 1973

TWO DISTINCTIVE VENATION TYPESIn Fagus grandifolia the secondary veins run

straight into the marginal teeth without

branching.

In Acer platanoides the primary veins all come

from the same point.

THERE ARE MANY OTHER

CHARACTERS ASSOCIATED

WITH LEAVES THAT HELP

IDENTIFY SPECIES

THE FOLLOWING SLIDES SHOW

SOME OF THEM

STIPULES OF POTENTILLA SIMPLEX

STIPULES

ARE BRACTS

ATTACHED TO THE

STEM AT THE

NODE WHERE THE

PETIOLE IS

ATTACHED.

THERE ARE TWO

STIPULES AT EACH

NODE.

STIPULES ARE

COMMON IN THE

ROSACEAE AS

SHOWN HERE.

LINEAR STIPULES OF STAPHYLEA TRIFOLIA

THE BLADDER NUT IS THE

ONLY SPECIES IN THE

PRESERVE WITH

PUBESCENT, LINEAR

STIPULES.

Photo by C. Gracie

STIPELS AT THE BASES OF TWO OPPOSITE

LEAFLETS

STIPELS OF

SAMBUCUS

CANADENSIS (THE

COMMON

ELDERBERRY).

STIPULES ARE FOUND

AT THE BASES OF

LEAVES WHEREAS

STIPELS ARE

LOCATED AT THE

BASES OF LEAFLETS.

STIPELS ARE ONLY

FOUND ON SPECIES

WITH COMPOUND

LEAVES.

PETIOLAR GLANDS OF PRUNUS SEROTINA

THE BLACK CHERRY IS

EASY TO IDENTIFY

BECAUSE IT HAS:

ALTERNATE, SIMPLE

LEAVES WITH SERRATE

MARGINS AND GLANDS AT

THE APEX OF SOME OF THE

PETIOLES.

THE GLANDS ARE NOT

APPARENT ON EVERY

PETIOLE SO LOOK AT

SEVERAL LEAVES. THEY

ARE ALSO MORE DIFFICULT

TO FIND ON OLDER

LEAVES.

STIPULAR-DERIVED TENDRILS OF SMILAX ROTUNDIFOLIA

THE CATBRIER IS

THE ONLY SPECIES

IN THE WLT

PRESERVE THAT

POSSESSES

STIPULAR-DERIVED

TENDRILS.

Photo by C. Gracie

GLANDULAR LEAF

PUNCTATIONS OF

SAINT JOHN’S-WORT

TO SEE THE PUNCTATIONS

VIEW THE LEAF AGAINST

THE SKY THROUGH A 10X

HAND LENS

LEAF PUNCTATIONS OF HYPERICUM PUNCTATUM

Photo by C. Gracie

TUFTS OF TRICHOMES IN THE AXILS OF SECONDARY VEINS

OF THE AMERICAN BASSWOOD (TILIA AMERICANA)

Photo by C. Gracie

STEMS ALSO HAVE CHARACTERS THAT HELP

IDENTIFY SPECIES

THE BURNING BUSH

(EUONYMUS

ALATUS) HAS

GREEN STEMS WITH

REDDISH-BROWN

WINGS. THESE

CHARACTERS MAKE

THIS SPECIES EASY

TO IDENTIFY. STEMS

LIKE THIS ARE

CALLED ALATE

(WINGED).

THE BURNING BUSH

IS A COMMON

INVASIVE PLANT IN

THE WLT PRESERVE.

FOR DEFINITIONS AND IMAGES

OF MORE BOTANICAL TERMS CLICK ON

“GLOSSARY” ON THE HOME PAGE OF THE

FLOWERING PLANTS