plant structure. plant body plan the apical–basal pattern and the radial pattern are parts of the...
TRANSCRIPT
Plant Body Plan• The apical–
basal pattern and the radial pattern are parts of the plant body plan
• They arise through orderly development
Plant Body Plan
• Plant development differs from that of animals
• The plant body is modular, and the growth of stems and roots is “indeterminate”
• Leaves, flowers, and fruits show “determinate” growth.
Plant Cells• Some produce a thick secondary wall• Adjacent cells are connected by plasmodesmata
extending through both cell walls
Angiosperms Monocots
– have a single cotyledon– narrow leaves with parallel veins– flower parts in multiples of three– stems with scattered vascular bundles
Dicots (eudicots)– have two cotyledons– broad leaves with netlike veins– flower parts in fours or fives– vascular bundles in a ring
Plant Tissue Systems
• Vascular tissue system conducts water, minerals, and the products of photosynthesis
• Dermal tissue system protects the body surface
• Ground tissue system produces and stores food materials; serves as “anchor”
Vegetative OrgansInclude:• roots, which
form a root system
• stems and leaves, which form a shoot system
Plant Body Plan
• Meristems are localized regions of cell division
• Apical meristems at the tips of stems and roots produce the primary growth of those organs
Plant Body Plan• In some plants, the products of
primary growth make up the entire plant body Other plants show secondary growth
• Two lateral meristems, the vascular cambium and cork cambium, are responsible for secondary growth
Plant Body Plan• Young roots have
apical meristems that gives rise to the root cap and 3 primary meristems
• 3 primary meristems produce the three tissue systems
Plant Body Plan
• Root tips have three zones: the zones of cell division, cell elongation, and cell differentiation
Plant Body Plan• The dermal
tissue system consists of the epidermis, part of which forms root hairs responsible for absorbing water and minerals
Roots • The cortex of a young root surrounds
the endodermis which controls access to the stele (pericycle, xylem, phloem)
Stems
• Vascular tissue in young stems is divided into vascular bundles, each containing xylem and phloem
• Pith occupies the center of the eudicot stem
• Cortex lies to the outside of vascular bundles in eudicots, and pith rays lie between them.
Stems and Roots • Many dicot stems
and roots show secondary growth, in which vascular and cork cambiam give rise to secondary xylem and phloem
• As secondary growth continues, wood and bark are produced
Photosynthesis• Mesophyll is the
photosynthetic tissue of a leaf
• Veins bring water and minerals to the mesophyll and carry products of photosynthesis to other parts of the plant body
Photosynthesis • A waxy cuticle
prevents water loss from the leaf, but is impermeable to carbon dioxide
• Guard cells control opening of stomata, leaf openings that allow CO2 to enter and water to escape