What Is a Cyme? A Flower Cluster That Opens From the Center
A cyme is a flower cluster where the first flower opens at the top or center. Later flowers open on side branches below or around it.
The short answer
Master Gardeners of Northern Virginia define a cyme as a flat or round topped determinate cluster. Each stalk ends in one flower, plus the first opens at the top or center. Iowa State notes cymes bloom from the inside out. NC State notes the main axis ends early in a flower.
How do you identify a cyme?
Watch the cluster as it begins opening. If the center or top flower opens first, it is a cyme. MGNV notes later flowers work their way out from the center or down the stalk.
| Cluster | Type | Opens first |
|---|---|---|
| Cyme | Determinate | Center or top |
| Raceme | Indeterminate | Bottom |
| Corymb | Indeterminate | Outer flowers |
Source: Iowa State plus NC State Extension.
How is a cyme different from a raceme?
NC State notes a raceme has a long axis with stalked flowers that goes on growing. In a cyme, a flower ends the axis early. Iowa State notes determinate clusters bloom top down or inside out.
Which plants have cymes?
MGNV shows cymose clusters on Virginia bluebells, daylily, comfrey, American beautyberry plus Autumn Joy sedum.
How to: step by step
- Pick a cluster just starting to open.
- See which flower opens first.
- Check whether it sits at the top or center.
- Trace the branches below it.
- Watch new flowers open on those branches.
- Compare with a raceme.
Troubleshooting
Center flower opens first: cyme.
Lowest flowers open first on one stem: raceme.
Edge flowers open first in a flat top: corymb.
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Sources
- Cyme (glossary), Master Gardeners of Northern Virginia
- Plant identification terminology: an illustrated glossary, Purdue Extension Master Gardener Program
- Glossary of garden terms, Iowa State University Extension and Outreach
- Extension Gardener Handbook, chapter 3: botany, NC State Extension
FAQ
Is a cyme determinate?
Yes. MGNV defines a cyme as a determinate cluster. NC State notes a flower ends the axis early in its growth.
What is a helicoid cyme?
MGNV cites a study on helicoid plus scorpioid cymes in forget me nots plus Virginia bluebells. These are coiled forms of the cyme.
Are cyme flowers grouped in threes?
NC State notes a cyme is broad, flat topped or domed, with flower clusters of threes on stalks of similar length.
How does the MGNV glossary show a cyme?
MGNV draws the first flower to bloom as the largest circle. Later flowers work out from the center or down the stalk.
How is a cyme different from a corymb?
Iowa State notes both are flat topped or rounded. A cyme blooms from the inside out while a corymb blooms from the outside in.
