5.5 The Flower

Vocabulary flashcards covering floral structures, reproductive classification, symmetry, floral appendage counts, and bract presence based on section 5.5 of the textbook transcript.

Flower

The reproductive unit in the angiosperms, meant for sexual reproduction.

Thalamus (Receptacle)

The swollen end of the stalk or pedicel on which the four whorls of a flower are arranged successively.

Accessory Organs

Floral organs that are not directly reproductive, specifically the calyx and corolla.

Reproductive Organs

Floral organs responsible for sexual reproduction, specifically androecium and gynoecium.

Perianth

The structure formed when calyx and corolla are not distinct from each other, as in lily.

Bisexual Flower

A flower that possesses both androecium and gynoecium.

Unisexual Flower

A flower having either only stamens or only carpels.

Actinomorphic

Floral radial symmetry where a flower can be divided into two equal radial halves in any radial plane passing through the centre (e.g., mustard, datura, chilli).

Zygomorphic

Floral bilateral symmetry where a flower can be divided into two similar halves only in one particular vertical plane (e.g., pea, gulmohur, bean, Cassia).

Asymmetric (Irregular)

Condition of a flower when it cannot be divided into two similar halves by any vertical plane passing through the centre, as in canna.

Trimerous

Describes a flower having floral appendages in multiples of $3$.

Tetramerous

Describes a flower having floral appendages in multiples of $4$.

Pentamerous

Describes a flower having floral appendages in multiples of $5$.

Bract

A reduced leaf found at the base of the pedicel.

Bracteate

Flowers that are provided with bracts at the base of the pedicel.

Ebracteate

Flowers that lack bracts at the base of the pedicel.