Herbal Anatomy - Leaves

I started with plant nature, like perennial vs. annual (back on January 6); Now I am going to give you some terminology and examples about the leaves.

Leaves are the most important part of an herb, as they are where the essential oils that give the plants their unique scents and flavors are held.  One can identify herbs by the shape, location and size of the leaves they produce.

NODE is the spot where leaves and buds are attached to the stem.

LEAF is the photosynthetic organ of a plant that is attached to a stem, generally at specific intervals.

WHORLED  an interval where stems, leaves or flowers, arise in a ring around the stem, usually not recognized unless the whorl includes three or more leaves or branches.

OPPOSITE an interval when leaves or buds are arranged in pairs each component on the opposite side of the branch

 THE LEAF

The leaf is commonly raised on an unexpanded part or stalk which is call the petiole, while the expanded portion is termed the lamina, limb or blade. When the vessels or fibers of the leaves expand immediately on leaving the stem, the leaf is said to be sessile. In such cases the petiole is absent. When the blade consists of a single piece, the leaf is simple; when composed of two or three more with a branched petiole, the leaf is compound.

The distribution of the veins or framework of the leaf in the blade is termed venation.

 A linear leaf is an elongated shape with nearly parallel sides.

A lanceolate leaf has the form of a lance;  wide in the middle and gradually tapering  at each end. Lemon Verbena is often described as this shape (see below) but it is really pinnate.

An ovate leaf is oval shaped.

Sage has a nice ovate leaf

an obovate leaf  is one having the veins more developed beyond the middle of the blade.

These leaves are obovate because the veins are so pronounced.  This is an heirloom rose (see the hip)

Betony with a wedge-shape leaf

A cuneiform  (or cuneate)  leaf is wedge shaped.

A cordate leaf is heart shaped.

A reniform is kidney shaped.

A sagittate leaf is arrow shaped.

 A hastate leaf  is shaped like the head of a spear with sharp basal lobes spreading away from the base of the petiole.

A peltate leaf is shaped like a shield.

A serrate leaf is one in which the margin is beset with sharp teeth, which point forward towards the apex.

The opposite leaves of this Apple mint are slightly serrate , the points angle toward the apex

A dentate leaf  the teeth are NOT directed towards the apex.

A crenate leaf has rounded teeth

catnip has rounded teeth

A sinuate leaf has alternate concavities and convexities (wavy)

rue leaves have non-uniform wavy edges

 A pinnate leaf is shaped like a feather

Lemon verbena is considered pinnate

A pectinate leaf has very close and narrow divisions, like the teeth of a comb.

A lyrate leaf has the shape of a lyre

A runcinate leaf is  a lyrate leaf with sharp lobes pointing towards the base, like a dandelion leaf.

A palmate leaf resembles the hand, usually with five veins rather than a five fingered look.

You can clearly see plantain's 5 veins

A pedate leaf  looks like a bird's foot. Usually three lobes or veins.

Purple bugbane has great bird track like leaves

Leaves which arise directly from a rootstock, not from an aerial stem are said to be radical.

Rosette leaves are clustered at ground level. (The hosta above has a rosette of leaves that are also radical!)

Sessil  leaves have no stalk.  Grasses are sessil.

lemon grass

Truncate leaves are cut off straight across.

In ferns the leaves are called fronds.

When a leaf at its outer edge has no dentations it is said to be entire. When a leaf has a jagged edge is it known as serrate or dentate. When the leaf terminates in an acute angle it is acute, when in an obuse angle it is obtuse. An obtuse leaf with the apex slightly depressed is retuse, or if more strongly notched emarginate.