Leaf Grammar

Leaf grammar is a phrase coined by Botany for the Curious for the way its illustrated guide to leaf shapes is organised. Leaf-shape terms are not a pile of separate names; they form a descriptive language whose parts combine. Shape, margin, venation and division each work like a word class, and most leaves can be spelled out by taking a term from each.

The four word classes

• Shape: the outline of the blade, the expanded part of the leaf. The tip (apex) and the base are described under shape.
• Margin: the edge of the blade.
• Venation: the way the veins are arranged.
• Division: whether the blade is whole or cut. A leaf is simple when it is undivided and compound when it is divided into separate parts; a lobe is one division of the blade.

Spelling a leaf

Take a term from each class and a leaf reads as a phrase: ovate, acuminate, rounded at the base, serrate, pinnately veined, simple. The example describes no particular species; it shows how the terms combine. Read it a word at a time.

Ovate: the outline is shaped like a lengthwise section through a hen's egg, broadest toward the base. Acuminate: the tip tapers gradually to a point. Rounded at the base: the base forms an even curve rather than an angle.

Serrate: the margin is set with teeth that point up toward the tip; the word comes from the Latin for saw. Pinnately veined: secondary veins branch off the midrib, the main vein of the leaf, and the term comes from the Latin for feather. Simple: the blade is a single piece, not split into leaflets.

What it leaves out

Leaf arrangement on the stem, called phyllotaxis, is not one of the word classes. It describes how leaves are placed along the stem, not the leaf itself.

The phrase organises terms; it is not a rule that leaves obey. Most leaves can be spelled this way, not every leaf.

How Botany for the Curious uses it

Botany for the Curious files each leaf-shape term under one word class and draws it from its definition. The other coined phrase with a page of its own is the sessile wager.

Source

The definitions in the example follow B. D. Jackson, A Glossary of Botanic Terms, 4th edition, revised and enlarged (London: Gerald Duckworth; New York: Hafner Publishing, 1928; reprinted January 1953), entries for leaf, lamina, blade, apex, margin, nervation, lobe, ovate, acuminate, serrate, antrorse, feather-veined, midrib, pinna and simple, restated in the guide's own words.