VEGETATIVE CELL TYPES IN SEED PLANTS

Examine the Differentiation Potential of all cell types.
 
CELL TYPE
SUBCATEGORIES
LOCATION 
ORIGINATES FROM
FUNCTION
EXAMPLES
MERISTEMATIC = SELF PERPETUATING
1.  Apical meristem
     A.  Single cell
     B.  Multiple cells
1.  Shoot
      A.  Terminal
      B.  Lateral
      C.  Adventitous

2.  Root
      A.  Terminal
      B.  Lateral
      C.  Adventitous

1.  Tip (apex) of vegetative stems, developing inflorescences, and flowers

2.   Beneath inner edge of root cap at tip (apex) of roots

A. Initial terminal population are lineal descendents of cells of embryo

B.  Subsequent lateral ones arise from existing shoot meristems or from pericycle of roots

C.  Adventitious 
meristem cells arise from vascular cambium, pericycle, and cortex parenchyma

  • Self perpetuating
  • Formation of primary meristmatic tissue
Coleus shoot apex

Allium root apex

2.  Vascular cambial cell 1.  Fusiform Initials

2.  Ray Initials

Between secondary xylem and secondary phloem A.  Procambium of fascicular regions and from parenchyma of interfascicular regions in stems.

B.  Procambium between xylem and phloem and periclycle outside xylem in roots.

Three year old twigs of
     Tilia
      Pinus
3.  Cork cambial cell (Phellogen)
  • Between cork (phellem) and either phelloderm, cortex, or phloem tissue
  • Beneath surfaces exposed by abscission of leaves and stems and wounds
  • Self perpetuating in tangential direction in some species; not in most
  • Formation of cork (phellem) in exterior radial direction
  • Formation of phelloderm in interior radial direction in some species
Three year old twigs of
      Pinus
     Tilia

Potato tuber

CELL TYPE SUBCATEGORIES LOCATION ORIGINATES FROM FUNCTION EXAMPLES
DERIVED EXCULSIVELY FROM PRIMARY MERISTEMS
4.  Epidermal 1.  Ground

2.  Trichomes

Outermost cell layer of foliar and floral organs; primary stems and roots Protoderm
  • Restriction of gaseous exchange
  • Protection against disease vectors
  • Storage of water and elaborated reserves
  • Absorption of water in roots and certain foliar structures
Leaves of
     Zea
     Bryophyllum
     Pinus
5.  Guard Cells Classified on basis of
Geometric or
Ontogenetic
relationships with
Subsidiary Cells
Outermost cell layer of foliar and floral organs; primary stems Guard Cell Mother Cells of the protoderm which may also form some or all of the associated Subsidiary 
Cells
  • Regulation of gaseous exchange
Leaves of
     Zea
     Bryophyllum
     Pinus
6.  Collenchyma Classified on basis of where the  thicker regions of primary cell wall are located within the cells Subepidermal layers or strands of stems, petioles,  larger veins of some leaves, and cortex of some roots. Ground meristem
  • Mechanical support of primary plant body
  • Photosynthesis
  • Carbohydrate storage
Stems of
     Solanum
     Helianthus

Rheum petiole

CELL TYPE SUBCATEGORIES LOCATION ORIGINATES FROM FUNCTION EXAMPLES
DERIVED FROM BOTH PRIMARY AND SECONDARY MERISTEMS
7.  Parenchyma Classified on basis of function or position in the plant body Most all plant organs Ground meristem, procambium, vascular cambium, and cork cambium
  • Dedifferentiation to form interfascicular cambium and adventitious shoots and roots
  • Hydrostatic support of primary plant body
  • Photosynthesis
  • Storage of water and elaborated reserves
  • Secretion and excretion of various substances
  • Formation of callus in response to wounding
Three year old twigs of
     Tilia
      Pinus

Potato tuber

Leaves of
     Zea
     Bryophyllum
     Pinus

8.  Sclereid Classified on basis of cell geometry Outer layer of seeds and some fruits; diffusely distributed in pith, cortex, phloem, outer bark,  and  leaf mesophyll Protoderm, ground meristem, procambium, vascular cambium, and phellogen. 

Also from sclerosis of parenchyma cells.

  • Protection of embryos and seeds
  • Mechanical support
Pyrus fruit
Phaseolus seed
Camellia petiole
Leaves of 
     Nymphaea
    Osmanthus
    Olea
9.  Cork
(Phellem)
Lenticels Peripheral regions of stems, roots,  certain fruits, some bud scales, and petioles; often produced in response to wounds Cork cambium (Phellogen)
  • Restriction of gaseous exchange
  • Protection against disease vectors and fire
Three year old twigs of
     Tilia
      Pinus

Potato tuber

10.  Fiber 1.  Bast (Phloem)
2.  Libriform (Xylem)
3.  Fiber-tracheid
Cortex, vascular tissues of stems and roots,  as strands or sheaths of leaf veins, epidermis of some leaves Protoderm, ground meristem, procambium, and vascular cambium
  • Mechanical support
Leaves of 
     Zea
     Helianthus

Twigs of
     Tilia
     Fraxinus

11.  Tracheid 1.  Vascular
2.  Vasicentric
Xylem, transfusion tissue of gymnosperm leaves Procambium, vascular cambium
  • Transport of water, elements, and some phytohormones
  • Mechanical support
Twigs of 
     Quercus
     Pinus
12.  Vessel member or element
Xylem Procambium, vascular cambium
  • Transport of water, elements, and some phytohormones
  • Mechanical support
Twigs of 
     Quercus
     Magnolia
13.  Transfer cell Classified on basis of location of wall ingrowths  in vascular tissue Primary xylem and phloem, pericycle of root nodules, stigmata of some flowers, secretory structures Procambium, protoderm
  • Transport of water, elements, and organic molecules over short distances where normal transport connections are not found
Legume root nodule

Anthocerus sporophyte/gametophyte
 

14.  Sieve cell
Gymnosperm Phloem Procambium, vascular cambium
  • Transport of photosynthate
Twigs of
     Pinus
     Thuja
15.  Sieve-tube member or element
Angiosperm Phloem Procambium, vascular cambium
  • Transport of photosynthate
Cucurbita stem
Liriodendron twig
16.  Laticifer Classified on basis of presence or absence of
     A.  Anastomoses
     B.  Articulations
Pith, xylem rays, phloem, cortex, leaf mesophyll Ground meristem, procambium, and vascular cambium
  • Secretion and storage of latex
Leaves of
     Allium
     Lactuca
     Asclepias
     Ficus
Stems of
     Ficus
     Cannabis