This section of the book is from "The Complete Herbalist" by Dr. O. Phelps Brown. Also available from Amazon: The Complete Herbalist: The People Their Own Physicians By The Use Of Nature's Remedies.
The leaf is commonly raised on an unexpanded part or stalk which is called the petiole, while the expanded portion is termed the lamina, limb or blade. When the vessels or fibres of the leaves expand immediately on leaving the stem, the leaf is said to be senile. 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 lanceolate leaf has the form of a lance.
An ovate leaf has the shape of ellipsis.
A cuneiform leaf has the shape of a wedge.
A cordate leaf has the shape of a heart.
A reniform leaf has the shape of a kidney.
A sagittate leaf is arrow-shaped.
A hastate leaf has the shape of an ancient halberd.
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.
A dentate leaf is one when these teeth are not directed towards the apex.
A crenate leaf has rounded teeth.
A sinuate leaf has alternate concavities and convexities.
A pinnate leaf has the shape of a feather.
A pectinate leaf is one having 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, as in the dandelion.
A palmate leaf is one bearing considerable resemblance to the hand.
A pedate leaf is one bearing resemblance to a bird's foot.
An obovate leaf is one having the veins more developed beyond the middle of the blade.
When a leaf at its outer edge has no dentations it is said to be entire. When the leaf terminates in an acute angle it is acute, when in an obtuse angle it is obtuse. An obtuse leaf with the apex slightly depressed is retuse, or if more strongly notched, emarginate. An obovate leaf with a wider or more conspicuous notch at the apex becomes obcordate, being a cordate leaf inverted When the apex is cut off by a straight transverse line the leaf is truncate; when abruptly terminated by a small projecting point it is mucronate; and when an acute leaf has a narrowed apex it is acuminate. In ferns the leaves are called fronds.