
Garden Word of the Day
Take $3 off planting calendars from Forging Time with the code DAILYGARDEN841. This is an excellent resource with some amazing photos.

Leaves come in a variety of shapes. Having a firm grasp of the vocabulary associated with leaf shapes can help you to identify and talk about plants more effectively. This is a HUGE subject, so, grab yourself a beverage and get comfortable. When describing leaf shape, some terms refer to the entire leaf, while others refer to specific parts of the leaf, such as the edge, tip, or base. Nearly all the terms are tied closely to the Latin word forms, so you are in luck if foreign language comes easily (or if you happen to already know Latin). Personally, I am not gifted in that particular area. Luckily for all of us, Latin is a pretty reliable language, when it comes to putting pieces of words together to make new words. Don’t let all these new words scare you off, and don't expect to be able to remember everything. You can always return to this page, or use a field guide, when describing leaf shapes or identifying unknown plants. The important thing is to become familiar with the different ways that leaves are described and categorized.
Leaf and leaflet silhouettes Leaves are first identified by their overall shape. They can be round, triangular, oval, rectangular, or diamondshaped:
Some leaves are shaped like a heart, kidney, fan, arrowhead, or spear:
Some leaves are shaped like a teardrop, while others look more like the silhouette of a violin, a spoon, a sickle, or a hand:
The Latin of lobes Some leaves have protrusions, called lobes, that can be rounded (like your earlobes) or pointed. Lobes can be arranged pinnately (in pairs) or palmately (like a hand). Lobes can be gently waving lines, they can be sharp incisions, or they can fall somewhere in between. These features are usually described as relative to the midrib line. Depending on the type of lobe a leaf might have, descriptive suffixes are added:
All about the base The way leaves attach to the rest of the plant can also provide clues for identification.
Here’s a tip At the other end of the leaf, tip shape can also provide clues for identification. Leaf tips can be:
There is a lot of variation in leaf tips:
Take it from the edge The edge of a leaf is called its margin. Leaf margins provide an easy classification tool, since this trait stays consistent within a species. At the most basic level, leaf margins are:
If the stem attaches to a leaf near the middle, rather than at an edge, it is peltate. [Nasturtium] If it looks as though the stem passes through the middle of the leaf, it is perfoliate. [Miner's lettuce]
You can find lots of online illustrations of leaf shapes, but, for right now, it has stopped raining and hailing and my garden is calling. How many different leaf shapes can you identify in your garden?
0 Comments
Leaves nearly always appear singularly or paired. There’s nothing unusual about that, but the mathematics behind those arrangements may surprise you. Take a look at a stem or flower from above. You will almost always see distinct patterns in the way the leaves and stems are organized. These patterns are called phyllotactic spirals. Very often, Fibonacci numbers and the Golden Mean (or Golden Angle) are involved. Fibonacci numbers are a big part of nature and architecture. You can get a simple explanation at the bottom of my post on garden design. Leaf attachment Leaves emerge along a twig or stem at points called nodes. The space between each node is called the internode. Sometimes, in the angled space between the leaf and the stem, called the leaf axil, a bud may appear. The scaly covering on buds is actually made up of modified leaves, called bud scales. Note that only leaf buds have scales; flower buds do not. Where leaves emerge, along a stem, is determined by plant hormones, called auxins. Leaf arrangement At the most basic level, leaves emerge from a stem either individually or in pairs. Leaves that take turns up a stem, alternating from one side to the other, are called alternate. Leaves that appear in pairs are called opposite. Leaves growing close to the ground, around an upright stem, whether alternate or opposite, are called basal. Leaves arranged like an upright deck of cards are called tworanked, or distichous [distikus].
Leaf arrangement math
The fraction of a circle used to arrange leaves around a stem is very species specific. You don’t have to be a math whiz to understand this stuff, either. Let me explain:
Now look at leaf arrangement along and around a stem in the same way:
Are you with me? Hang in there! This stuff is amazing! So, since leaves and stems are different sizes, and species have different sunlight needs, there are different fractions, or ratios of rotation, around a stem. For example, hazel leaves are arranged in 1/3 (or 120°) rotations, apricots use 2/5 rotations, sunflowers and pears use 3/8, and almonds use 5/13. This means that the leaves of an almond tree are positioned 5/13th of the pie apart. If you do the math, this works out to 38.5° between each leaf attachment, as you work your way up or down a stem. This is where it gets really weird! The fractions that describe leaf arrangement are almost always made with a Fibonacci number and its successor, as the numerator and denominator, respectively. Now, the number of steps taken for a leaf arrangement to work its way around a stem, before repeating the pattern, is called its gyres. A three leaf cycle of rotation has one gyre, while a five leaf cycle takes 2 gyres. The number of gyres ends up being the numerator in the Fibonacci number that describes the rotation! Holy spring bulbs, Birdman! Whorls take this math to a whole new level The rotation of successive whorls is nearly always onehalf the angle between the leaves. For example, say you have a whorled leaf arrangement that uses three leaves. From what we calculated above, there would be 120° between each of those leaves, along the length of the stem. All the other whorls will be half that distance, or 60° apart from each other. I have no idea why. Bottom line: whether leaves are alternate, opposite, whorled, basal, or distichous, the mathematics of leaf arrangement ends up providing each leaf with the optimal amount of sunlight. [If you really love this stuff, check out Gray’s Botanical Textbook: Structural Botany (1879)] 
Welcome!You can grow a surprising amount of food in your own yard. Ask me how! To help The Daily Garden grow, you may see affiliate ads sprouting up in various places. These are not weeds. Pluck one of these offers and, at no extra cost to you, I get a small commission. As an Amazon Associate I earn from these qualifying purchases. You can also get my book, Stop Wasting Your Yard!
Index
All
Archives
July 2022
