Leaf Terminology

alternate leaves

lead arrangement alternate from side to side

opposite leaves

two leaves per node

whorled

three or more leaves per node

leaf blade

the main part of the leaf that captures sunlight and performs photosynthesis

midvein

the central, most prominent vein

secondary veins

veins emerging from the midvein

tertiary veins

veins emerging from the secondary veins

petiole

the stalk that joins the leaf to stem

sessile

lack of petiole

stipule

little outgrowth at the base of the petiole

parallel leaf venation

pinnate/reticulate leaf venation

palmate leaf venation

linear

long and slender with sides that remain close to the midrib throughout its length, giving it a uniform width from base to tip

oblong

2–4 times longer than it is wide, with nearly parallel sides and rounded ends, giving it a long, rectangular outline

elliptic

oval, football‑shaped leaf that is widest at the middle and tapers equally toward both the apex and the base

broadly elliptic

wider proportion than a typical elliptic

very broadly elliptic

wider proportion than a broadly elliptic

narrowly elliptic (lanceolate)

narrower proportion than elliptic

very narrowly elliptic

narrower in proportion than narrowly elliptic

ovate

egg-shaped, with the broader end at the base and the narrower end at the tip

obovate

egg-shaped with the broader end at the apex and the narrower end attached to the stem or petiole

truncate

apex appears cut off squarely or nearly straight across, forming a flat edge

obtuse

blunt or rounded leaf tip where the angle between the leaf margins exceeds 90 degrees

acute

leaf tip that gradually tapers to a sharp point, forming a terminal angle between 45° and 90°

acuminate

sides that curve concavely or inward toward the tip, then tapering to a fine, long, slender point

retuse

notched apex

cuspidate

abruptly acuminate

caudate

very long and narrow abruptly acuminate

mucronate

midvein pokes out

falcate

curved like a sickle

rounded

gradually come together to form a smooth, rounded shape, without tapering sharply to the petiole

cuneate

a narrow, wedge-like shape where the sides of the leaf converge toward the petiole or stem, forming a tapering base

cordate

heart-shaped base with a deep notch

reniform

broad, rounded shape with a concave base where the petiole attaches, resembling a kidney

oblique

base is not symmetrical

hastate

spear-shaped, with two basal lobes spreading outward at roughly right angles from the petiole, giving it a distinctive arrowhead appearance

sagittate

arrowhead-shaped leaf with two pointed lobes extending downward from the base

clasping (amplexicaule)

base of leaf wraps around stem with lobes

perfoliate

base (or blade) is completely fused around the stem, so that the stem appears to pass through the center of the leaf

peltate

petiole goes to center of leaf

simple

has a single, continuous blade called the lamina, where any divisions do not extend the central vein

pinnately lobed

has a single central midrib with lobes arranged along both sides like the barbs of a feather

palmately lobed

has lobes that spread out from a single point at the base, resembling the fingers of a hand

pinnately compound

compound leaf divided into multiple leaflets arranged along a central rachis, giving it a feather‑like appearance

bipinnately compound

twice-divided leaf in which the main leaf axis (rachis) branches into secondary axes (pinnae), each bearing multiple leaflets

palmately compound

multiple leaflets radiate from a single central point at the end of the petiole

entire

leaf margin is smooth

erose

irregular leaf margin

dentate

tooth-like margin, point ~90 degrees from midvein

serrate

pointed margins tilted towards the top of leaf

doubly-serrate

each larger serration has a smaller one

crenate

scalloped leaf margin

flat

leaf lies flat

involute

leaf curls up

revolute (recurved)

leaf curls down

convolute

one margin wraps over other