1. A spur-shaped anatomical projection or appendage, especially in botany and zoology.
Usage: technical; biology
2. In botany, a tubular or sac-like extension of a flower petal or sepal.
Usage: botanical

Examples

• The delphinium flower has a prominent calcar that extends backward from each petal.
• Many orchids possess a calcar that stores nectar for pollinators.
• The calcar of the columbine flower is distinctive and attracts hummingbirds.
• Botanists examine the calcar to help identify and classify flowering plants.
• The tubular calcar serves as an adaptation for specific pollinator species.