What Is an Undulate Margin? Wavy Leaf Edges
An undulate margin is a leaf edge that is wavy rather than flat. The Manual of Leaf Architecture hosted by Penn State defines undulate as a margin that forms smooth curves in and out of the plane of the leaf. NC State Extension notes the shapes of blades plus margins help identify plants.
The short answer
An undulate margin is a wavy leaf edge that does not lie flat. The Manual of Leaf Architecture defines it as smooth curves in and out of the leaf plane. NC State Extension defines sinuate as a pronounced wavy margin. Look along the edge from the side to see the waves, then check several mature leaves.
What does undulate mean?
The Manual of Leaf Architecture defines undulate as smooth curves in and out of the plane of the leaf. The term covers the margin, which NC State Extension calls the edge of the leaf. It says nothing about the outline of the blade, so a leaf can be ovate plus undulate at the same time.
| Term | Meaning | Source |
|---|---|---|
| Undulate | Curves in and out of the leaf plane | Penn State manual |
| Sinuate | A pronounced wavy margin | NC State |
| Entire | A smooth edge with no teeth or notches | NC State |
| Toothed | Coarse, fine, sharp or blunt teeth | Utah State |
Source: Manual of Leaf Architecture, NC State Extension plus Utah State University Extension.
How is undulate different from sinuate?
The Manual of Leaf Architecture places undulate curves in and out of the leaf plane. NC State Extension calls a strongly wavy margin sinuate. Both describe a wavy edge with no teeth, so study how the waves run before naming the margin.
Which plants have undulate margins?
The NC State Extension page on lambsquarters lists undulate among its leaf margins. Its leaves are smooth margined with some teeth or undulate lobes plus carry a white mealy coating. One plant can show more than one margin type.
How to: step by step
- Hold a mature leaf at eye level.
- Sight along the edge from the side.
- Check if the margin rises plus falls.
- Gentle waves with no teeth point to undulate.
- Compare with teeth or lobes cut into the blade.
- Check several leaves before naming the margin.
Troubleshooting
Waves resemble teeth: viewed from above. Look from the side.
Margins vary on one plant: mixed leaf types. Check several leaves.
Waves change with leaf age: new growth. Use mature leaves.
For more on leaves see cannabis leaf anatomy, cannabis nodes and internodes plus companion plants when growing marijuana. Kind Seed Co also stocks cannabis seeds.
Sources
- Manual of Leaf Architecture, Cornell University Press, hosted by Penn State
- Extension Gardener Handbook, chapter 3: botany, NC State Extension
- Chenopodium album (lambsquarters), NC State Extension Gardener Plant Toolbox
- Tree and botanical glossary, Utah State University Extension Forestry
FAQ
Why do botanists describe leaf margins?
NC State Extension notes the shapes of leaf blades plus margins are useful in identifying species plus cultivars of plants. It lists margin terms such as entire, sinuate, crenate plus serrate. Naming the margin narrows down a plant quickly, especially when flowers or fruit are not present on the plant.
Is an undulate margin the same as an entire margin?
Not quite. NC State Extension defines an entire margin as a smooth edge with no teeth or notches. The Manual of Leaf Architecture defines undulate as curving in and out of the leaf plane. A leaf edge can lack teeth yet still wave, so note both the outline of the edge plus whether it lies flat.
Does an undulate margin have teeth?
No teeth are needed. The Manual of Leaf Architecture describes undulate as smooth curves in and out of the leaf plane, while Utah State University Extension describes a toothed margin as one with coarse, fine, sharp or blunt teeth. Some plants mix the two, so check where the teeth sit plus where the edge simply waves.
How do I check for an undulate margin?
Hold a mature leaf level with your eyes plus look along the edge from the side. Waves that rise plus fall out of the flat surface of the blade point to undulate. Compare a few leaves, since NC State Extension notes a single plant such as lambsquarters can show more than one margin.
Does lambsquarters have undulate leaves?
Yes. NC State Extension lists undulate among the leaf margins of lambsquarters, along with entire, lobed plus serrate. Its leaves are smooth margined with some teeth or undulate lobes. The page also notes a white mealy coating made by tiny hairs, which is densest on the leaf underside.
