Plant Biology Lab Week 7: Anatomy II- Primary Growth

Tap root system

1 main root with branches

What kind of plants have a tap root system

Dicots and gymnosperms

Fibrous root system

Roots from stems and other roots

What kind of plants have a fibrous root system

Monocots

What are the functions of roots

Water uptake, mineral absorption, anchoring, and storage

Primary root

Root morphology parts

Lateral roots, root hairs, mucilage sheath, and root cap

Lateral roots

Used for soil exploration and anchoring

Root hairs

Used for water and mineral absorption; has a large surface area

Mucilage sheath

Decreases friction/damage from soil particles; has a role in rhizosphere microbial community (fungi and bacteria)

Root cap

Protection of root tip and meristem

What are root caps covered in

Sloughed cells and mucigel

Where do new cells in plants come from

The apical meristem

Columella

Central column of cells; starch filled plastids for gravity detection

Regions of the root

Region of cell division, region of elongation, and region of maturation

Region of cell division

Addition of new cells

Region of elongation

Cell elongate; causes most increase in root length

Region of maturation

Cells differentiate and mature; root hairs produced

Root apical meristem

Region of cell division, undifferentiated tissue, continually dividing (source of new cells), quiescent center

Quiescent center

Area with low division rate; activated by damage

Primary meristems in roots

Next to apical meristem

Parts of primary meristems in roots

Procambium, protoderm, and ground tissue

Procambium

Becomes vascular tissue

Protoderm

Becomes epidermis

Ground tissue in primary meristem

Becomes ground tissue

Exodermis

Layer just inside epidermis with high suberin content; inhibits microorganisms and prevents water loss

Endodermis

Has Casparian strips; thickened primary walls and middle lamella, high suberin and lignin content; materials must enter endodermal cells, can’t go between

Casparian strips

Limit what gets into vascular cylinder

Pericycle

Just inside endodermis; outermost layer of vascular tissue. Where lateral roots originate

Shoot systems

Made up of stem and leaves

Stem functions

Support and conduction

Leaves function

Photosynthesis