plant cells and tissues

botany, dr. kohnen

continuous growth

indeterminate growth

perpetual embryogenesis

plant undergo this with meristematic cells

meristematic cells

cells divide, one remains meristematic and one differentiates

three basic cell types

parenchyma, collenchyma, and sclerenchyma (categorized based on cell walls)

parenchyma

• thin cell walls

• remain alive at maturity

• metabolically active

• three types: chlorenchyma, glandular cells, and transfer cells

chlorenchyma

photosynthetic

glandular cells

produce resin (ex. pine sap)

transfer cells

contoured cell walls to increase surface area

collenchyma

• thickened wall cells

• elongaded

• vines

sclerenchyma

• thick cell walls (lignified)

• often die at maturity

• found in mature tissues

• mechanical and conducting

mechanical sclerenchyma

• fibers (slight flexibility while being sturdy)

• sclerids

conducting sclerenchyma

• conduct water

• tracheids and vessel elements

tracheids

• gymnosperms

• pit membrane = middle lamella

vessel elements

• angiosperms

• perforation plate

• water can move through smoothly

xylem

conducts water, includes trachear elements and fibers

phloem

• translocate photosynthate (product of photosynthesis - sugar)

• composed of sieve tube elements (STE’s)

STE

• sieve tube elements

• sieve cells = gymnosperms (naked seed)

• sieve tube elements - angiosperms (covered seed)

• live in close association to companion cells that assist them

dermal tissues

• epidermis

• guard cells

• trichromes

epidermis structure

cuticle

guard cells

control size of pore, allowing gas exchange

trichromes

• hair-like structures

• deter herbivores

guard cell pores

needed for transpiration