BIOLOGY

Meristems Unlike animals, plants have permanent regions of cell division Meristems

Meristems Apical Meristems Cell division at tips of roots and stems Produce primary tissue

Meristems Lateral Meristems Cell division that increases girth of roots and stems Secondary growth

Lateral Meristems Vascular cambium Conduction “Plumbing”

Complex Tissue Xylem Conducts water and minerals from the roots Transports upward

Complex Tissue Xylem Openings along cell walls connect side by side cells Lateral flow in trees Rays

Complex Tissue Phloem Conduct water and food in both directions Primarily down

Lateral Meristems Cork cambium Layer of cells outside phloem layer of vascular cambium Inside the outer bark

Dicots Dicotyledonous Two leaves emerge from seed Dicot Cotyledons Not true leaves

Dicots Herbaceous dicots Soft tissue Primary xylem/phloem only Annual dicots Germinate and die in one season Perennial dicots Regrow new tissue from roots

Dicots Woody dicots Hard tissue Secondary xylem and phloem Perennial woody dicots only Live multiple seasons

Secondary xylem Secondary xylem cells produced inside cambium Toward center of stem Transports water and nutrients up the plant

Secondary xylem Secondary xylem eventually becomes wood As cells become inactive, they become structural

SPRING WOOD Active growth produces large xylem cells Lighter colored band

Summer wood Smaller and fewer XYLEM cells Darker band

GROWTH RINGS The alternation of spring and summer growth bands Fire, drought, and other events Increment borer to read rings

Heartwood versus sapwood Inactive xylem cells Accumulation of resins, gums, and tannins Darker color of wood Sapwood active xylem (near cambium) Lighter color wood

Heartwood versus sapwood Heartwood can rot but tree can still function Portion of heartwood and sapwood can be removed

Girdling phloem Phloem nearest cambium transport the most sugars Cambium stripped from grapevines to trap sugars

Cork Cambium Outer bark of woody plants Developed from epidermis Cork cells Also called phellogen Impregnated with suberin Waxy substance

Monocots Vascular bundles throughout stem Xylem facing center Phloem facing out

Monocots No tree rings Palm trees Do not seal wounds

Xylem, Phloem, and Transpiration https://www.youtube.com/watch?v=xGCnuXxbZGk