LEAF TERMINOLOGY

THE GOAL OF THIS PRESENTATION IS TO HELP VISITORS IDENTIFY THE FLOWERING THEY SEE WHILE HIKING IN THE WESTCHESTER WILDERNESS WALK.

TO LEARN HOW TO IDENTIFY FLOWERING PLANTS YOU WILL NEED TO LEARN BASIC 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 IS ONE OF THE MOST IMPORTANT TOOLS OF A BOTANIST.

MANY OF THE CHARACTERS CAN ONLY BE OBSERVED WELL WITH A HAND LENS. BASIC LEAF TERMINOLOGY

THE POSITION AND COMPLEXITY OF PLANT ARE TWO OF THE FIRST CHARACTERS TO LOOK AT WHEN IDENTIFYING PLANTS.

ALL OF IN THE PRESERVE HAVE SIMPLE LEAVES. IN ADDITION THE LEAVES ARE ATTACHED OPPOSITE TO ONE ANOTHER ON THE STEM.

THE ONLY OTHER GENUS WITH OPPOSITE, SIMPLE LEAVES IS (DOGWOOD) BUT THAT GENUS HAS ENTIRE, NOT LOBED, LEAF BLADES. Drawing by B. Angell BLACK 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 is the leaf. There are no 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 LEAF FEATURES

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!

From Hickey, 1973 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 TYPES In the secondary veins run straight into the marginal teeth without branching.

In 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 OF POTENTILLA SIMPLEX

STIPULES ARE ATTACHED TO THE STEM AT THE NODE WHERE THE IS ATTACHED.

THERE ARE TWO STIPULES AT EACH NODE.

STIPULES ARE COMMON IN THE AS SHOWN HERE. LINEAR STIPULES OF TRIFOLIA

THE BLADDER NUT IS THE ONLY SPECIES IN THE PRESERVE WITH PUBESCENT, LINEAR STIPULES. STIPELS AT THE BASES OF TWO OPPOSITE LEAFLETS

STIPELS OF 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.

Photo by C. Gracie 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 OF ROTUNDIFOLIA

THE CATBRIER IS THE ONLY SPECIES IN THE WLT PRESERVE THAT POSSESSES STIPULAR-DERIVED TENDRILS. LEAF PUNCTATIONS OF PUNCTATUM

GLANDULAR LEAF PUNCTATIONS OF SAINT JOHN’S-WORT

TO SEE THE PUNCTATIONS VIEW THE LEAF AGAINST THE SKY THROUGH A 10X HAND LENS

Photo by C. Gracie TUFTS OF IN THE AXILS OF SECONDARY VEINS OF THE AMERICAN BASSWOOD ()

Photo by C. Gracie STEMS ALSO HAVE CHARACTERS THAT HELP IDENTIFY SPECIES

THE BURNING BUSH (EUONYMUS ALATUS) HAS 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.

Photo by C. Gracie FOR DEFINITIONS AND IMAGES OF MORE BOTANICAL TERMS CLICK ON “GLOSSARY” ON THE HOME PAGE OF THE FLOWERING PLANTS