- Umbel
- A flower cluster in which the individual flower stalks grow from the same point, like the ribs of an umbrella.
- Understock
- The plant providing the root system to which the top variety is attached in bud-grafting. Also called a root stock.
- Unisexual
- A flower of one sex only.
- Utility easement
- The portion of a property owned by the municipality and containing the sewer, water, gas, and electric lines. They have the right to remove anything planted in this area in order to service those lines.
