Download AP Notes Plant Anatomy 09

Basic Plant Anatomy
Growth & Reproduction
http://www.phschool.com/science/biology_place/biocoach/plants/intro.html
(great website for checking
labeling & understanding)
Shoot System
 Stems: above ground, supports leaves & flowers
o Terminal bud:* tip of stem has developing leaves & nodes
o Axillary buds: formed where the leaf and node meet, usually dormant,
forms a branch
 Leaves:* main photosynthetic organ
o Nodes:* point at which leaves are attached
 Apical dominance:* Auxin in the terminal bud inhibit growth in axillary buds
Root System
 Anchors, absorbs, stores food and transport minerals & water
 Root Hairs:* increase surface area, extension of the epidermis
Plant Cells
 Parenchyma Cells*
o Alive when mature, usually only have primary walls
o Used in photosynthesis, aerobic respiration & food storage
o Makes up the bulk of the plant
 Collenchyma Cells*
o Alive when mature, unevenly thickened primary walls
o Provide flexible support in the growing parts of plants

Sclerenchyma Cells*
o Dead when mature, very thick secondary walls with lignin
o Fibers:* long & slender, arranged in bundles
o Sclereids:* short, thick with irregular & hard secondary walls; hard part of
nutshells, makes pears gritty
Plant Tissues
 Dermal Tissue*
o Outer protective covering, 1st line of defense
o Epidermis:* outer surfaces, covered with a waxy cuticle

Stomata:* pores in the epidermis, CO2 & O2 exchange
 Ground Tissue*
o Used in photosynthesis, storage & support
o Two parts: pith and cortex
o Endodermis*

Selective barrier between cortex and vascular tissue

A cylinder one cell thick
o Mesophyll*

Ground tissue in the leaf, between the upper and lower epidermis

Composed of parenchyma cells
 Vascular Tissue
o Provides support and long distance transport
o Xylem: water-conducting cells

Tracheids, vessel elements
o Phloem: food-conducting cells

Sieve-tube members, companion cells
o Vascular cylinder: has both xylem and phloem