Plant Anatomy 2006-2007

Basic Plant Anatomy root shoot (stem) leaves root tip root hairs nodes internodes buds terminal or apical buds axillary buds flower buds & flowers leaves mesophyll tissue veins (vascular bundles)

Leaves Function of leaves simple vs. compound photosynthesis energy transformation organic matter production gas exchange transpiration simple vs. compound

colored leaves (poinsetta) Modified leaves tendrils (peas) spines (cacti) succulent leaves colored leaves (poinsetta)

Interdependent Systems Both systems depend on the other roots depend on sugars produced by photosynthetic leaves shoots depend on water & minerals absorbed from the soil by roots sugars water & minerals

Plant TISSUES Dermal Ground Vascular epidermis (“skin” of plant) single layer of tightly packed cells that covers & protects plant Ground bulk of plant tissue photosynthetic mesophyll, storage Vascular transport system in shoots & roots xylem & phloem

Structure–Function again! Vascular tissue vessel elements Xylem move water & minerals up from roots dead cells at functional maturity only cell walls remain need empty pipes to efficiently move H2O transpirational pull vessel element dead cells Aaaah… Structure–Function again! tracheids

Phloem: food-conducting cells carry sugars & nutrients throughout plant sieve tube companion cell sieve plate plasmodesmata living cells

Structure–Function again! Aaaah… Structure–Function again! Phloem Living cells at functional maturity cell membrane, cytoplasm control of diffusion lose their nucleus, ribosomes & vacuole more room for specialized transport of liquid food (sucrose) Cells sieve tubes sieve plates — end walls — have pores to facilitate flow of fluid between cells companion cells nucleated cells connected to the sieve-tube help sieve tubes

Phloem: food-conducting cells sieve tube elements & companion cells

Plant Growth

Growth in Plants Specific regions of growth: Meristems Stem cells: perpetually embryonic tissue Regenerate new cells Apical shoot meristem growth in length primary growth Apical root meristem Lateral meristem growth in girth secondary growth

Apical meristems shoot root

Growth in Woody Plants Woody plants grow in height from tip Primary xylem Growth in Woody Plants Woody plants grow in height from tip primary growth apical meristem Woody plants grow in diameter from sides secondary growth lateral meristems vascular cambium makes 2° phloem & 2° xylem cork cambium makes bark Primary phloem Epidermis Lateral meristems Secondary xylem Primary phloem Primary xylem Secondary phloem Annual growth layers Bark

Secondary Growth Secondary Growth growth in diameter thickens & strengthens older part of tree cork cambium makes bark growing ring around tree vascular cambium makes xylem & phloem

Where will the carving be in 50 years?