Plant Tissues

Homebox Genes

Controlls Embrogensis

Early Plants

Sperm was flagellated; conifers and flowerers sperm not flagated;

Transcription factors WOX2 & WOX8

Expressed in Zygote & regulates cell fate and specialization

The plant Organs

Stem, Leaf, and roots

Tissue systems in the plant

Dermal, Vascular, and ground

Tissues in Dermal Tissue system

Epidermal tissue; Guard cells/Stomata

Epidermal tissue

Covers the entire plant except at meristems; closely packed cells; secretes cuticle; protects against damage and water loss; grows trichomes

Trichomes

the small hairs on the surface of plants; Reflects U.V; prevents transperation; insulates contains anthocyanins

Guard cells/Stomata

Responible for gas exhange and transperation; On leafs, stem, and some roots, contains chloroplast and is stimulated by light

Transpiration

Water leaving though the stomata; allows for water to travel up the plant; can cool the plant

Vascular tissue system

Responible for transporting nutriends and water

Phloem tissue

On the outside of the vascular bundle; Transports non-water; On the bottem of leafs

Xylem tissue

On the inside of the vascular bundle; Transports Water; on the inside to prevent freezing; On the top of leafs

Xylem Vessel member XVM

Main H20 conductor and only in flowering plants; hollow; dead at maturity; perforation plates at the ends for vertical water transport and pits or lateral; stack to make xylem vessel; High in ligin;

Trachieds

Conduct waters; tapered ends; pits in walls; no perforation plates; high ligin; in flowering and conifers

Fibers

Specialized for support; High in Ligin; Dead at maturity;

Parenchyma

Insulate/Storage/Change into other cells; Do injury repair; ALIVE; thin walled; no lignin; Does photosyntheiss in leafs

Sieve tube members STM

Main sugar conductor; Sieve plates at ends (cellulose plate with pores); Has a companion cell; Alive; No vacuole and no nucleus to make space for sugar;

Companion Cells

Small; Thin; keeps STM alive and connected by plasmodesmata

Collenchya

Just below epidermis; uneven thinkened walls; very flexable so has high matrix and low cellulose

Sclereids

Antipredation and breaks insects probosci

Ground tissue system

Not the Epidermis and Veins

Palisade Mesophyll

Long cells on the top of leafs; responsible for most of photosythesis; very packed together

Bundle Sheath

Surrounds minor veins and conducts sugar from palisade to phloem; large in C4 plants

Spongy Mesophyll

Has lots of holes for gas exchange; Below palisade; Irregular shaped; fed by stomata on bottem of the leaf. Made of Parenchyma Cells

Eudicot stem vs monocot stem