STUDY OF THE EXTERNAL STRUCTURE OF PLANTS? MORPHOLOGY
STUDY OF THE INTERNAL STRUCTURE OF PLANTS? ANATOMY or HISTOLOGY
Perennial crops e.g. GRAPES
Annual - a plant that completes its life cycle in one season and dies (e.g. wheat, subclover, peas, beans) Biennial - a plant that requires two seasons to complete its life cycle. Vegetative phase and flowering phase (e.g. carrot, onion) Perennial - a plant that lives from year to year (e.g. apple, citrus, tea bush) Ephemeral - very short lived plants (e.g. desert and tundra plants) Plant life cycles
Single seed leaf or cotyledon • embryo contains: • coleoptile -- a sheath in which the true leaves and plumule grow • plumule: origin of young leaves --> growing point, crown or node • radicle ---> initial seminal roots • coleorhiza -- protective sheath for the radicle • Tillers - axillary shoots that grow later from the growing point • Secondary roots form later, often with tillering Monocotyledons
Adventitious roots grow from the shoot axis just at or above the soil surface.
seed has 2 seed leaves /cotyledons • cotyledons either hypogeal (below ground) or epigeal (above ground) • embryo • radicle ---> primary root • hypocotyl - lifts the cotyledons above the soil • epicotyl - main stem and growing point • apical and axillary growing points • secondary roots branch from the primary root to form a structured deep root system Dicotyledons
Monocotyledonous plants tend not to have a dominant tap root, instead, the roots branch in many directions creating a fibrous root system. Dicotyledonous plants tend to have a dominant tap root, which develops downward, together with limited lateral root growth.