Plant Form Chapter 36

Plant Classes Seed producing plants: Gymnosperms Angiosperms Dicotyledons (dicots) Monocotyledons (monocots)

Plant Classes

Plant Body Organization All vascular plants consist of: Root system Shoot system

3 basic tissue types Ground Dermal Vascular

Plant Growth is limited. Growth and development of adult plants is Adult cell growth is limited. Growth and development of adult plants is dependent on specialized cells called meristems.

Apical Meristem Located at tips of stems and roots.

Lateral Meristem Produce wood and bark in trees and bushes – called secondary growth.

Vascular Tissue - Xylem Main water-transportation tissue Also transports dissolved minerals, NO3 and PO4. Provides stem support.

Vascular Tissue - Phloem Principal food-conducting tissue in vascular plants Carries glucose and starch created during photosynthesis

Roots Four regions are commonly recognized: Root cap Zone of cell division Zone of elongation Zone of maturation

Stages in the differentiation of plant tissues

Modified Roots Most plants produce either/or: Taproot system – single large root with small branch roots Fibrous root system – many small roots of similar diameter Some plants, however, produce modified roots with specific functions Adventitious roots arise from any place other than the plant’s root

Prop roots Aerial roots Buttress roots Pneumatophores Water storage roots

Stems Undergo growth from cell division in apical and lateral stems Shoot apical meristem cells create stem tissue as well as leaves, other shoots, and flowers.

Parts of the Stem

Eudicot (Dicot) stem Monocot stem

Leaves Principal site of photosynthesis Expand by cell division and cell enlargement Growth stops at maturity

Leaf Structure Cuticle Epidermis Palisade mesophyll Spongy mesophyll Vascular bundles Guard cells Stoma

Modified Leaves Insectivorous Bracts Reproductive Spines