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Phytohormones

Organic chemical messengers in plants that regulate growth, movement, and responses to stimuli.

Main functions of phytohormones

Stimulate shoot and root growth, promote tropic movements, aid fruit ripening, promote flowering, break seed dormancy, regulate stomatal movement.

Meristematic tissues

Plant parts responsible for growth; include apical & intercalary meristems that increase length and vascular cambium that increases girth.

Three phases of plant growth controlled by hormones

Cell division, cell enlargement, cell differentiation.

Transport of phytohormones to target parts

Produced in one part, transported by vascular tissues, or diffuse to other parts.

Plant Growth Regulators (PGRs)

Another name for plant hormones; some stimulate and some inhibit growth, regulating overall plant development.

Plant response to environmental stimuli

Through phytohormones that coordinate slow chemical-based responses.

Example of rapid plant response

Mimosa pudica folds its leaves when touched.

Why plant responses are slower than animal responses

Plants lack nerves and use chemical signals instead of fast electrical impulses.

External factors influencing hormone production in plants

Conditions like drought, salinity, and light.

Structures helping in transport of plant hormones

Vascular tissues (xylem and phloem).

Tropic movements

Directional growth movements of plants in response to stimuli like light (phototropism), gravity (geotropism), etc.