1. PHARMACOBOTANY LECTURE 4. PLANT TISSUES II.

2. DERMAL TISSUES OF THE PLANT
epidermis: primary dermal tissue of the shoot
rhizodermis: primary dermal tissue of the root
function: protection, transpiration, gas exchange,
photosynthesis, secretion, absorption
one layer  tunica (protoderma),
rarely more than 1 cell layer (e.g. Ficus, Nerium oleander)

6. Nerium oleander leaf cross section

7. Ficus sp. leaf cross section
epidermis

8. Abies tűlevél km10x upper epidermis + cuticle lower epidermis
Abies sp. needle
Abies tűlevél km10x
upper epidermis + cuticle
lower
epidermis
xeromorphic stomata

9. Valeriana officinalis root
rhizodermis

10. EPIDERMIS Epidermal cells: tightly linked
little cytoplasm, no chloroplast
large central vacuole – water storage – protects from desiccation
Epidermal cells – additional cell wall materials:
cutin (procutin – teichodes – polimerization)  cuticle
in the form of layers (pectin, cellulose and cutin)
wax, lignin, silicic acid

11. EPIDERMIS Epidermis cell shapes (height/width):
isodiametric: H/W= 1-1.5
anisodiametric: H/W= 1.5-5
prosenchymatic: H/W5
Surface view – anticlinal wall (perpendicular to plant surface):
rectangular, wavy, lobate

12. lobate cell walls

13. Stomata stoma guard cells ER chloroplasts epidermis cell
Kalanchoe sp.
epidermis cell
stoma neighbor cell
Arabidopsis thaliana

15. Stomata Stoma - location:
Leaves, young stems (floral leaves, below-ground stems); but never on roots.
Astomatic leaf
Stomatic leaf:
- hypostomatic
- epistomatic
- amphistomatic

16. Stomata Stoma position – as related to epidermal cells:
mesomorphic – medium level water supply
hygromorphic – abundant water supply
xeromorphic – dry habitats (stomatal crypt)

17. mesomorphic stoma position
Iris sibirica
leaf of Iris sp.

18. nectary of ‘Freedom’ apple
hygromorphic

19. leaf cross section of Nerium oleander
xeromorphic
(stomatal crypt)

20. Stomata
On the basis of guard cell structure, and mechanisms regulating the opening and closure of stomatal pore:
1. moss-fern type
2. pine type
3. Amaryllis type
4. grass type
1. Moss-fern type:
swelling of guard cells occurs perpendicular to plant surface  thin inner edge of guard cells

21. Stomata 2. Pine type: - guard cells are sunken
- closure between upper thickenings

22. Stomata 3. Amaryllis type: - angiosperms: most frequent
- bean-shaped guard cells, in cross section: or
high turgor pressure (high light intensity, high humidity)  guard cells open the pore in a plane parallel to plant surface
closed stoma
water molecules
stomatal pore
cellulose fibers
open stoma
Amaryllis

23. Agropyron pectiniforme
Stomata
4. Grass type:
guard cells: dumb-bell shaped,
subsidiary cells: triangular or trapezoid
Agropyron pectiniforme

24. Phragmites ep.40x guard cells triangular subsidiary cells
epidermis cells
leaf epidermis of weed

25. Zea mays ep.40x triangular subsidiary cells guard cells
epidermis cells
leaf epidermis of maize

26. Stomata II. Number and arrangement of subsidiary cells:
No subsidiary cell: anomocytic
1 subsidiary cell: desmocytic
2 subsidiary cells: diacytic (perpendicular to guard cells)
paracytic (parallel to guard cells)
3 (5) subsidiary cells: anisocytic
6 subsidiary cells: hexacytic
More than 6 s.cells: actinocytic, heliocytic, cyclocytic

27. desmocytic
anomocytic
diacytic
tetracytic
actinocytic
hexacytic
anisocytic

28. Hedera sp. - anomocytic

29. Senna sp.: paracytic stoma
subsidiary cells
Capsella bursa-pastoris:
anisocytic stoma

30. PLANT HAIRS / TRICHOMES

31. Trichomes Origin: epidermal meristemoids (trichoblasts)
Structure: base + stalk + head
Aspects of classification:
Unicellular - Multicellular
Branched - Unbranched
Soft - Rigid (calcium carbonate, silicium dioxide)
Pointed – Blunt
Living (secreting) – Dead

32. Trichomes LM I. Non-glandular (dead) trichomes:
petal (Helianthus)
papilla
I. Non-glandular (dead) trichomes:
Papilla (Plural: papillae)
– epidermal protrusions
stigma
SEM
stigma surface in pear flower
Cover hairs
unicellular (e.g. Boraginaceae – bristles / setae)
bifid hairs (e.g. Humulus lupulus)
seed hairs (e.g. Gossypium)
multicellular (e.g. Verbascum – multi-level, branched)
stellate hairs, scales (e.g. Elaeagnus)

33. Non-glandular trichomes
multi-level, branched cover hair
bristle/seta
papillae
unicellular
multicellular
stellate hair scale
Non-glandular
trichomes
bifid hair

34. Mentha p.levél derített4x
trichomes
epidermis cells
Mentha x piperita
cleared leaf

35. Zea mays ep.szőrök.40x
trichomes
epidermis cells
maize leaf

36. Althaeae folium_10x upper epidermis lower epidermis Ca(COO)2 crystals
trichomes
Althaea officinalis leaf

37. Non-glandular hairs / Cover hairs
Elaeagnus sp.:
scales
Borago sp. – bristle

38. Non-glandular hairs / Cover hairs
Verbascum sp.
multi-level branched hair
Humulus lupulus
bifid hair

39. Rosae pseudofructus - trichomes

40. Trichomes II. Glandular trichomes (living, cytoplasm-containing):
Salt-secreting (e.g. Tamarix, Limonium)
Nectar-secreting (e.g. Lonicera, Vicia faba)
Mucilage-secreting (Rumex, Rheum)
Essential oil secreting (Lamiaceae, Asteraceae)
Glandular scale (e.g. Humulus lupulus)
Colleter (e.g. bud scales of Aesculus)
Stinging hair (Urtica)
(Tentacles of carnivorous plants (e.g. Drosera, Pinguicula))

41. II. Glandular trichomes
stinging hair
colleter
capitate glandular hair
multicellular, peltate glandular hair
(seed hairs: non-glandular)

42. Glandular hairs Pelargonium sp. capitate glandular hair
Artemisia vulgaris
8-celled glandular hair

43. Glandular hairs Juglans regia multi-cellular capitate glandular hairs
Salvia sclarea
capitate glandular hairs

44. Glandular hairs Salvia nemorosa – leaf cross section
Lamiaceae type glandular hair
(glandular scale)
Thymus vulgaris – surface view
Lamiaceae type glandular hair

45. glandular
trichomes
Flower of mallow

46. Glandular hairs
Urtica dioica: stinging hairs (large hairs) and cover hairs (small hairs)

47. Urtica csalánszőr20x
stinging hair
head
epidermis

48. stinging hairs

49. tentacles of insect-trapping sundew (Drosera)
Trichomes
Emergences:
superficial outgrowths – more complex than trichomes
epidermis + ground tissues (vascular tissues)
Drosera spatula
tentacles of insect-trapping sundew (Drosera)
prickle of rose
Indument(um): all the hairs of a plant

50. Secondary dermal tissue / Periderm
Stems and roots with secondary thickening:
– in the place of primary dermal tissues (epidermis, rhizodermis)
- perennial gymnosperms and dicots (angiosperms)
Primary dermal tissue torn off → traumatins, kinetins
Primary cortex: reembrionalisation → secondary meristem
phellogen / cork cambium:
 phellem / cork
 phelloderm / cork ground tissue
periderm

51. Secondary dermal tissue / Periderm
Bark/Cortex/ Rhytidoma:
periderm torn off
 new cork cambium
 new periderm
Frangulae cortex
Quercus cortex
periderm elements are mixed with phloem elements:
bark / cortex:
glycosides, tannins, crystals, alkaloids, resin
Lenticels:
below stomata – lenticel cambium  loose cell aggregation – ensures gas exchange
end of vegetation period: covering cork layer

52. primary cortex
phellem/cork
phellogen/ cork cambium
phelloderm
parenchyma

53. rhytidoma
cork cambium
bark of
Frangula alnus

54. Quercus suber
cork oak