Floral Morphology: Botanical Parts and Definitions

The stalk of an individual flower.

A cyclic group in a flower. The four whorls are the calyx, the corolla, the androecium, and the gynoecium.

The sepals collectively, forming the outermost floral whorl.

One member of the outermost whorl of a flower. Collectively, the sepals make up the calyx.

The petals of the flower.

One member of the second whorl of a flower. Collectively, the petals make up the corolla.

• Dicots usually have 4 or 5 petals or multiples of 4 or 5.
• Monocots usually have 3 petals or multiples of 3 petals.

The calyx and corolla together.

The male sporophyll whorl within the flower, consisting of all stamens.

One member of the androecium. Each consists of a filament and anther, where pollen is produced. Collectively, stamens make up the androecium.

• Tetradynamous – four long and two short stamens.
• Monadelphous – stamens united by filaments into one column.
• Diadelphous – stamens united by filaments into two groups.

The structure containing pollen.

The innermost whorl, composed of all carpels.

One member of the gynoecium. Each carpel consists of an ovary, style, and stigma. Carpels collectively form the gynoecium.

• Apocarpous – separate carpels (many simple pistils).
• Syncarpous – fused carpels (compound pistil).
• Unicarpellate – a single carpel (simple pistil).

The sticky receptive surface on the pistil where pollen adheres.

A term for either a single carpel or fused carpels.

A flower having both stamens and pistils.

A flower with all four whorls: sepals, petals, stamens, and pistils.

Staminate and pistillate flowers occur on the same plant.

Staminate and pistillate flowers occur on different plants.

An ovary located above the calyx.

An ovary located below the calyx.
Hold the flower upright (pedicel down) to determine position.

A flower with multiple axes of symmetry (radial symmetry).

A flower with only one axis of symmetry (bilateral symmetry).

A two-lipped corolla shape.

A bell-shaped corolla.

A funnel-shaped corolla.

A strap-shaped floret, like in some Asteraceae.

A butterfly-shaped, zygomorphic corolla.

A flattened, wheel-like corolla.

A tubular base flaring sharply at the apex.

A corolla with a spur extension.

A single flower on a peduncle.

An unbranched axis with sessile flowers.

A fleshy spike with reduced, often unisexual flowers, subtended by a spathe.

A small spike with subtending bracts (typical of grasses).

An unbranched inflorescence with pedicellate flowers.

A raceme with pedicels of different lengths creating a flat top.

An inflorescence where all pedicels arise from a single point.

An umbel whose primary rays bear secondary umbels (e.g., Apiaceae).

An inflorescence where the central flower opens first.

Flowers arranged in a ring at the same node.

A branched raceme with rebranching.

A dense cluster of small flowers on a common receptacle (e.g., sunflower).