I’ve recently completed some botanical illustrations for The 21st Century Herbal by Michael Balick (published later this year by Rodale) and several illustrations of leaves, demonstrating different terms, were commissioned.
I think knowing what variations exist in nature helps you to look closer at a subject you’re drawing; so I thought I’d share some of it with you. The terms discussed are in bold text; the examples are all illustrations I've done over the years; and if you find any mistakes feel free to tell me, I'm no botanist, just a keen and interested amateur.
When illustrating plants you must consider the leaf structure, its shape, its margins, its venation, and the position of the leaves in relation to one another and the stem.
This would result in a frighteningly long blog, so for today I’ll just discuss compound vs simple leaves, and some basic shapes of simple leaves.
First, establish whether your leaf is simple, (in one piece) or compound (a leaf blade which is subdivided into smaller leaves, known as leaflets). A good trick here is to look for a bud. Buds only occur at the junction of a leaf stem (petiole) and the main stem. They never appear at the base of a leaflet’s stem (called a rachis). This is shown in my illustration of different forms of compound leaves below.
Compound leaves and simple leaves come in a wide variety of shapes. For example; a chestnut leaf, spreading its hand-like shape, is a compound leaf, made of 5 to 7 leaflets, all anchored centrally. The little leaflets are arranged a little like the fingers of a hand, hence the term palmate.
A leaf from the clover family (represented here by the bird’s foot trefoil) consists of three little leaflets, again, attached to one central point. The term translates the English “three-leaved” into latin terminology: trifoliolate.
Sometimes, what appears to be a branch or sprig of leaves are, in fact, one leaf composed of many leaflets. This is true of the ash.
Confused? Use the trick of searching for the bud. It’s at the junction of the sprig with the stem, you never see a little bud at the base of an individual leaflet. This array is called pinnate, and in this case it’s an odd pinnate example since there’s one leaflet at the tip without a pair. You can also get even pinnate leaves (like the mimosa) where every leaflet has a pair, including at the tip of the rachis. Just to make things even trickier, if each leaflet is divided again (stay with me, and picture an acacia, if you can) this is called doubly compound, or bipinnate.
You’ve established your leaf is not compound. If there is a bud to be seen, it’s at the base of the leaf stem. Your leaf is simple. But your life is not; because all leaves are by no means alike. There’s a vast amount of shape variation amongst leaf shape (and a bit of variation between botanists who sometimes use different terms for these shapes. In this blog, my references are Botany: A functional Approach by W. Muller, and Botany: A Textbook for Colleges by Hill, Popp, and Grove.)
The easiest shape to identify is Linear, or line-like. Lavender and rosemary are examples.
A cordate leaf is somewhat heart-shaped; mulberry and lime are examples.
Ovate leaves are egg-shaped, with their base a little wider than their middle and their tip a little thinner than the middle; as with the beech leaf.
A lanceolate leaf is a very narrow ovate (egg-shaped) leaf; it tends to be at least 6x longer than it is wide. Willow leaves are lanceolate.
Elliptical leaves are widest in their middle and taper evenly on either side of this. Mint, cherry, and sage leaves are examples.
Oblong leaves are broad and un-tapered. An example is the olive, and rhododendron. Here’s the overview of simple leaf shapes in one image:
There are many other leaf shapes, such as orbicular, rotundifoliate or peltate (all terms relate to leaves which are round, like a nasturtium) and sagittate (like an arrow) to name but two. (For further discussion and examples, please follow this link from the University of Maryland.)
From the remit I had in doing the illustrations for The Rodale 21st Century Herbal, this is most of what I examined. I hope some of it helps people as much as it has helped me.
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