Dev. Bio

The sun

Position

Shoot Apical Meristem

Auxillary bud

Seed leaves--protective material comes out of soil first

Stem above cotyledons

Stem portion between cotyledon and root

Junction between main stem and leaf

Meristems

the growing tip of shoot and root

• Tunica-outer layer-L1 and L2
• Corpus-inner layer-L3
• Central zone-slow cell division-renews meristem
• Peripheral zone-rapid cell division-cells form organs

Cell destination

• L1-Epidermis
• L2-Bulk of leaf and flower-albino layer, does not make chlorophyll'
• L3-Inner layer of leaf

position of leaf on stem

• Spiral phyllotaxy
• Whorl phyllotaxy

137 degrees

180 degrees

Plants can change from whorl to spiral from chemical changes or external manipulation (cut the meristems)

Auxin

Secreted from the apical meristem and allows for cell elongation and growth response to light/gravity.  Plants grow to a point because there is more auxin at the bottom of the plant.

Found in leaf axils and produce axillary buds

apical dominance--suppress axillary meristems get Christmas tree appearance

get bushy appearance

Adventitious-forms from surface cells on stems and leaves; bushy appearance even w/o SAM

Cylinder type-Cambrium layer (which allows for lateral growth) causes increase in width of plants/bark production

grows into soil

• Root cap-for protection
• Zone of cell division-meristematic region just below the root cap
• Zone of cell elongation-where cells elogate
• Zone of cell differentiation-where cells differentiate into Xylem and Phloem as well as where lateral roots and root hairs form
• Quiescent center of root meristem-contains slowly dividing cells