Roots

1
Roots

• Chapter 25

2
Root function

• Anchor plant in soil
• Absorb water and mineral nutrients
• Storage of food and water

3
Root origins

• Develops from radicle in embryo
• Radicle produces either
• Taproot
• Fibrous roots (adventitious roots)

4
Oat (Monocot) Root development at 31,45, and 80
days -Fibrous root system
5
Taproot-left Fibrous root-right
6
Dicot root
7
Root structure

• Root cap
• Region of cell division
• Region of cell elongation
• Region of maturation

8
Root cap

• Mass of parenchyma cells covering root tip
• Secretes slimy substance to ease movement
• Orients root down

9
Region of cell division

• Location of apical meristem
• Produces protoderm (root epidermis), ground
  meristem (cortex), and procambium (root vascular
  tissue)

10
Region of elongation

• Above region of division
• Cells enlarge in width and length, vacuoles
  enlarge

11
Region of maturation

• Cells mature into primary tissues and
  differentiate
• Root hairs located here, cuticle (wax) is lacking
  here

12
Closed system of Apical root organization
13
Open type of root apical organization
14
Development of Root Tip
15
Root Hairs-lateral Extensions of root Absorb
water and nutrients from soil
16
Maize roots
17
Casparian Strips in Buttercup root
Endodermis-single layer of cells with cell
walls having suberin pericycle-produces
lateral branch roots
18
Casparian Strip-Regulates water movement
19
Root development in woody dicot
20
Willow root anatomy
21
Lateral roots in Willow (Salix)
Lateral roots develop in pericycle, push through
endodermis, cortex, and epidermis (differs from
branches on stems)
22
Specialized roots

• Food-storage roots-potatoes,beets
• Water-storage roots-Pumpkins
• Propagative roots-adventitious roots
• Pneumatophores-mangroves,aerate roots
• Aerial roots-special plants
• Buttress roots-stability in trees
• Parasitic roots-attach to host plants for feeding

23
Aerial roots in an orchid
24
Fleshy roots-Sweet Potato and Sugarbeet
25
Human relevance and use of roots

• Source of food-sugar beets, beets, turnips,
  rutabegas, parsnips, horseradish, carrots, sweet
  potatoes, yams, cassava (yuca)
• Spices-sassafrass, sarsaparilla, licorice,
  angelica
• Dyes-madder
• Drugs-ipecac
• Insecticides-Rotenone