Chapter 6
Investigations on epidermal
morphology of leaf
6. INVESTIGATIONS ON EPIDERMAL MORPHOLOGY OF
LEAF
Investigation on epidermal features of leaf comprises the study o f nature of
stomata and guard cells, epidermal cells and hairs or trichomes in all the
experimental plant species. Stomatal frequency and index were also calculated.
Details o f the procedure for studying these epidermal features have been described
under “Materials and Methods”. Some qualitative and some quantitative criteria
have been investigated in each plant.
Epidermal features have been described following the classification and
terminology as suggested by Rajagopala and Ramayya (1981).
The leaves o f Calotropis gigantea Br., Calotropis procera Br. and
Calotropis acia Hamilt. appear to be similar with each other except few characters.
Young parts and undersurface o f leaves covered with white floccuse tomentum,
contrarily such white floccuse tomentum was not found in Asclepias curassavica
Linn., Hoya parasitica Wall, and Hoya arnottiam Wight. The leaf surface of the
Hoya species was highly waxy and the cuticle was very thick without any hairs and
trichomes.
Hairs and trichomes were not observed in the investigated plant species. But
some surface outgrowth as covering or vestitures in the lamina were found to be
present on the lower surface of the leaf in case o f Calotropis gigantea Br,,
Calotropis procera Br., Calotropis acia Hamilt. and also in Asclepias curassavica
Linn, epidermal surface o f Hoya parasitica Wall, and Hoya arnottiana Wight were
rough and waxy due to the thick and hard cuticle. Surface outgrowth was totally
absent in these two Hoya species.
Epidermis Mean no..
of
epidermal
ceils ±SE
W
8c
D
'•w'
to
o
*
y'00-'s
t
i
1
1
CN
5.0(±0.12) 1.65
2.34
2.5(10.92) 2.8
7.5(11.16)
4.67
1.95
2.5
CN
l
I
»o
ri
1
to
o
y-N
O
t
0s
00
vd
sfN
Os
i
s
SO
to
O
©
fN
? !
a
VO
6%
3.0(±0.18) 2.67
8.0(±0.09)
5.60
3.57
7222020
y“N
CO
fN
avo
0.05%
Range of
length of
epidermal
cells pm
4.37
y^N
fN CN
CN
a
37(10.76) 5.67%
>•“■*>»
OO
§
swo
00
Lower
«o
1
?! Os'
s«o
Os'
aCN
<d
Wight
i
OO
VO
12000
fN
<N
$
d
4.0
oo
(±022)
§
1
5.48%
5
(±0.27)
v-/
Os
oo
fN
0.02%
vq
a
H.
arnottiana
1
t
t
Lower
Upper
1
f
to
y—\
Wall.
1 vd
OOOO
fot
Upper
1
s-/
1
Linn.
/—S
00
*1
H.
parasitica
%
i
5.0(±0.67)
I
rn
12.8%
p
00
i rto oo
CN
407(±0.11) 52(10.06) 11.33%
20000
4(±0.S4) 0.02%
i
Upper
Sto
3.95
s
?
pcn
A.
curassavica Lower
I
4.94%
VO
$
S«q'
<N
i
500(±0.70)
1
to
Lower
l
C. acia
4.31
3.75
L/B
of
guard
cells
^
r- cs <1
VO —•
i r-* i vo
oo cq
«o
cn CN
622-10.5 S2.9-10.2
2.4-10.00
5.0013.66
3.3-12.66
6.001224
2.9010.10
2.7512.10
5.2722.78
52925.94
3.9-12.0
Range of
breadth
of the
epidermal
cells pm
4.232.2012.44
14.09
4.003.403.0(±0.03) 4.17
10.11
12.09
i 5.0-1624 3.3-1220
3.50-12.7
4.35
Breadthof
guard
cells
pm±SE
Os
O
VO *-* O1
Hamilt
t
6%
L/B of Length of
stomata! guard cells
pore
pm±SE
to
Upper
1
533(±0.62) 32(±0.21) 5.66%
1
7.12(±0.27) 1.9(±0.09)
l
5.9%
Breadth of
stomatal
pore
pm±SE
1
492(±0.22) 29(±0.09) 5.57%
Stomatal Stomatal Length of
frequency stomatal
index
pore
pm±SE
1
Lower
Mean
No. of
stomata
±SE
1
C. procera
Br.
Upper
C. gigantea
Lower
Br.
Name of
the taxa
Table No. VIH: Summary and comparison of the foliar epidermal features of the six taxa, (Calotropis gigantea Br., Calotropis procera Br.
Calotropis acia Hamilt., Asclapias curassavica Linn., Hoya parasitica Wall, and Hoya arnottiana Wight)
1 C" *—<
a
fO
'w'
»q
fN
s?
a
S'
«o
«i
to
a
VO
to
©
1
VO
6
|c4
Extipulate,
dorsiventrai,
hypostomatic,
subsessile, ovate,
thick, leaf base
cordate with oricled
lobes.
rn
parasitic or
rubiaceous
type
Size is variable, Sinuous
polygonal, both
upper and
lower cell wall
were very thick.
4-10cm
d
7-17cm.
5-12cm
5-13cm
12-22cm
N O
E
o
d•
(N
Wight.
Anomocytic
or
rananculous
type
Cell wall
Variable in
size, no definite curved
shape due to
highly curved
cell wall
7-13cm
15-23cm
Oval or
round
Elliptical
Parasitic or
rubiaceous
type
Sinuous
Variable in
size, polygonal,
upper
epidermal wall
thin, lower
epidermal wall
thick, compact
and single
layered
Entire
6-11cm
Stomatal type Stomatal
pore
Cell wall
Epidermal cell
shape size
Measurements of lamina Cuticle
Length
Breadth
r *-
H. arnottiana
Exstipulate,
dorsiventrai,
hypostomatic,
Linn.
subsessile,
lanceolate, soft, leaf
base entire.
H. parasitical Exstipulate,
isobilateral,
Wall.
amphistomatic,
subsessile, elliptic,
acute, thick, leaf
base is acute and
entire
A.
curassavica
Br.
C. acia
Hamilt.
C. procera
C. gigantea
Br.
Name of the 1 Lamina type
plant
2-4
2-4
| 4-5
2-4
2-4
No. of
subsidiary
cells
2-4
Smooth,
soft, covered
with very
fine tuft of
wooly hairy
structure.
Rough and
waxy
Smooth
shinning,
glaucus,
leaf surface
covered with
white
floccose
tomentum
Leaf surface
Table No. IX: Analysis of the leaf epidermis of the six experimental plants, (Calotropis gigantea Br., Calotropis procera Br., Calotropis acia
Hamilt., Asclapias curassavica Linn., Hoya parasitica Wall, and Hoya arnottiana Wight.)
2
E
oCN0
o1
E
000
d1
©
£
r-ot
d
76
Investigations on epidermal morphology o f leaf
In Calotropis gigantea Br.; Calotropis procera Br. and Calotropis acia
Harnilt the leaf surface were smooth, shinning, glaucus and covered with white
floccose, tomentum. In Asclepias curassavica Linn., the leaf surface is smooth, soft
and covered with fine tuft o f wooly hairy structure.
6.1
Epidermal morphology of Calotropis gigantea Br.
Leaves were hypostomatic, dorsiventral, exstipulate, subsessile and leaf
margins were entire. The size of the leaves varied and was 10 to 20cm. long and 6 to
11cm. broad. The shape o f leaf was ovate, oblong and acute. The leaf base is
cordate with auricled lobes. The under surface o f young leaves were covered with
waxy coating causing a shinny, sometime whitish or bluish tinge at young stage.
Often the leaves were covered with white floccose tomentum which look like hair
(Fig. No. 13d).
Cuticle:
The cuticle was thick and entire due to heavy cuticular deposition o f cellular
extract (Fig. No. 13c). Different aspects o f epidermis o f Calotropis gigantea Br.
have been shown in the Table No. VIII and DC
Upper epidermis:
The cells in the upper epidermis were thin walled, uninucleate, richly
cytoplasmic and variable in size and shape. The length of upper epidermal cells were
varied between 4.23 - 14.09 pm and the breadth were found as 2.20 - 12.44 pm
respectively. (Table No. VIII). These cells were found highly chrorophyllus
Fig. No. 13 (a-d): Microphotographs of leaf epidermis in experimental plant
(15x40x)
0
(a ) Calotropis gigantea Br. low er
epidermal cells w ith stomata
(c)
Calotropis gigantea Br. upper
epiderm is with cuticle
(b )
Calotropis gigantea Br. upper
epiderm al cells
(d )
Calotropis gigantea Br. low er
epiderm al out growth
77
_____
Investigations on epidermal morphology o f leaf
_
generally polygonal in shape. The cell walls were slightly sinuous. Stomata were
completely absent in the upper epidermis (Fig. No. 13b).
Lower epidermis:
The lower epidermal cells were elongated and polygonal in shape, compact
and single layered. Stomata were found to be distributed in the lower surface. The
size of lower epidermal cells were found to be varied between 4.00 to 12.09pm in
length and 3.40 to 10.11pm in breadth (Table N o.VHI). The lower epidermal cell
wall was also found to be slightly sinuous in shape. The stomata were found to be
paracytic or parallel celled type (rubiaceous) (Fig. No. 13a). One significant
observation was that each stoma was accompanied on either side by one or more
(often two) subsidiary cells, the longitudinal axis of which are parallel to that o f the
guard cells and pore. The stomatal pore was elliptical. The measure o f stomata! pore
were found 7.12 (±0.27) pm long and 1.9 (±0.09)pm breadth. The ratio o f length
and breadth of stomatal pore were found as 3.75. The guard cells were kidney
shaped or bean shaped with thick inner walls surrounding the pores and with thin
outer wall. The mean number of lower epidermal cells and stomata for some
selective area of lower epidermis were observed and found as 4.92±0.22 and
29±0.09 respectively. The stomata were generally scattered all over the surface of
lower epidermis but occasionally occurring in groups. The stomatal frequency and
stomatal index were calculated as 5.9% and 5.57% respectively. The guard cells
were also measured and the length and breadth of guard cells were found as 12.50
(±0.68)pm and 3.0(±0.03) pm respectively. The length and breadth ratio o f guard
cells were observed as 4.17.
Fig. No. 14 (a-d): Microphotographs of leaf epidermis in experimental plant
(15x40x)
(a) Calotropis procera Br. lower
epidermal cells with stomata
(d)
Calotropis procera Br. lower
epidermal outgrowth
(b>Calotropis procera Br. upper
epidermal cells
(c)
Calotropis procera Br. upper
epidermis with cuticle
78
Investigations on epidermal morphology o f leaf
6.2
Epidermal morphology of Calotropis procera Br.
Calotropis procera Br. is a shrub resembling Calotropis gigantea Br. The
leaves were dorsiventral, hypostomatic, exstipulate, subsessile, oblong and opposite.
The size of the leaves were slightly larger than those of Calotropis gigantea Br. The
leaves were measured and ranged between 15 - 23 cm. by 7 -1 3cm. in length and
breadth respectively. The shape of the leaves were similar to those of Calotropis
gigantea Br. In Calotropis procera Br. the leaf surfaces were also waxy and shinny
*
/
and the lower epidermis possesses tufts of wooly hairs. (Fig. No. 14d).
The cuticle was found entire and thick due to deposition o f cellular materials
(Fig. No. 14c). The different aspects of both upper and lower epidermis were
presented in the Table No. VIII and DC
Upper epidermis:
The cells in the upper epidermis were similar to those of Calotropis gigantea
Br. except for their size. The length o f the upper epidermal cells were varied
between 5.0 to 16.24 pm and the breadth between 3.3pm to 12.20pm. The cells
were polygonal, uninucleate and highly chlorophyllus. The ceil wall was slightly
sinuous like Calotropis gigantea Br. As in Calotropis gigantea Br. stomata were
completely absent in the upper epidermis (Fig. No. 14b).
Lower epidermis:
Morphologically the lower epidermal cells were similar to those of
Calotropis gigantea Br. Somata were present only in the lower epidermis. The
stomata were o f paracylic or parallel celled type (Fig. No. 14a). The stomatal pore
Fig. No. 15 (a-d): Microphotographs of leaf epidermis in experimental plant
(15x40x)
(a) Calotropis acia Ham i It. lower
epidermal cells w ith stomata
(d )
Calotropis acia Ham ilt. low er
epidermal out growth
(b )
Calotropis acia Ham ilt. upper
epiderm al cells
(c )
Calotropis acia Ham ilt. upper
epiderm is with cuticle
79
______________________________ Investigations on epidermal morphology o f leaf
was found elliptical and 6.90(±0.06) pm in length and 1.6(±0.18)pm in breadth. The
ratio between length and breadth was found to be 4.31. The guard cells were also
measured as 13.05 (± l.ll)p m long and 3.0(±0.91)pm broad. The ratio between
length and breadth was found to be 4.35 (Table No. VIII and IX). The inner walls of
the guard cells were found thick and outer ones were thin. The stomata were
scattered. The mean number of epidermal cells and stomata were observed as
533(±0.62) and 32(±0.21), respectively. The stomatal index and stomatal frequency
were 5.66% and 6% respectively.
The average length and breadth of lower epidermal cells ranged between
5.25 to 14.17pm and 3.50 to 12.70 pm respectively.
63
Epiderm al morphology of Calotropis acia Hamilt.
Calotropis acia Hamilt. is an undershrubs. The young parts o f the plants and
leaves were floccose and tomentose. The mature leaves have thick and glabrous
surface without any hairs on the upper surfaces. While the lower surface was
covered with fine white woolly tufts of hairs, Fig. No.(15d). The leaf sizes were
slightly different as they were smaller than those of other two species o f the genus
i.e. Calotropis gigantea Br. and Calotropis procera Br. The length o f leaves ranged
from 12 - 22cm. and the breadth ranged from 5 - 13cm. The shape of the leaves
were almost similar to those of Calotropis gigantea Br. and Calotropis procera Br.
and were obovate to oblong. The leaf surface were also similar to that of other two
species. The cuticle is entire and thick due to cellular deposition (Fig. No. 15c).
80
Investigations on epidermal morphology o f leaf
U pper epidermis:
The upper epidermal cells were more or less similar to those of the two other
species studied except for their sizes. The length of upper epidermal cells were
varied between 5.0 to 14.09 pm and breadth were found as 2.90 to 10.10pm. The
cells were polygonal uninucleate and highly chlorophyllus. Here also the cell walls
were slightly sinuous (Fig. No. 15b).
Lower epidermis:
The shape and pattern of lower epidermal cells were almost similar to those
o f the other two species of the genus Calotropis studied. As the leaves were
dorsiventral and hypostomatic, stomata were present only on lower epidermis. Here
also the stomatal type were found as paracytic or parallel celled type (Fig. No. 15a).
They were known as Rubiaceous type. The stomatal pore was found as elliptical and
measured as 7.50(±0.18)pm long and 1.9(±0.22)pm wide. The ratio between the
length and breadth of the stomatal pore was calculated as 3.95. The guard cells were
also measured and the value of the length of the guard cell were found as
13.10(±1.11) pm and 3.0(±0.88)pm as breadth. The ratio of the length and breadth
of the guard cells were found as 4.37. The inner wall of guard cells was found thick
and outer wall was thin. The guard cells were kidney or bean shaped. The stomata
were found scattered all over the lower epidermis. The number o f epidermal cells
and stomata o f the microscopic field were observed and the number of epidermal
cells were found as 500(±0.70) and number o f stomata were found as 26(±0.18). The
stomatal index and stomatal frequency were found 4.94% and 5.2% respectively.
Fig. No. 16 (a-d): Microphotographs of leaf epidermis in experimental plant
(15x40x)
(a) Asclepias curassavica Linn, lower
epidermal cell with stomata
(c) Asclepias curassavica Linn, upper
epidermis with cuticle
(b>Asclepias curassavica Linn, upper
epidermal cell
(d) Asclepias curassavica Linn, lower
epidermal out growth
81
_____________________________ Investigations on epidermal morphology o f leaf
Among the three species of Calotropis the stomatal frequency and stomatal
index were found highest in Calotropis procera Br. which was almost equal to
Calotropis gigantea Br. and the value were slightly lower in Calotropis acia Hamilt.
The length and breadth ratio of the stomatal pore was also high in Calotropis
procera Br. The length and breadth ratio of guard cells of Calotropis procera Br.
and Calotropis acia Hamilt. were almost equal. The different features of the
epidermal cells and the guard cells were shown in the Table No.VDI and EX.
6.4
Epidermal morphology of Asctepias curassavica Linn.
Asclepias curassavica Linn, is a perennial erect herb where the leaves were
exstipulate, opposite, dorsiventral, hypostomatic and subsessile. The shape of the
lamina were found lanceolate, acuminate and membranous. Leaf base was acute and
petiole were observed as 1.3 to 2.5cm. long. The size and shape of leaf was different
than the species of Calotropis. The length and breadth of leaf were varied between 4
to 10cm. and 0.75 to 3.8cm. respectively.
Leaf surface was found soft and covered with very fine tuft of wooly hairy
structure (Fig. No.l6d). The lamina is thinner than that of the species of Calotropis
studied.
Cuticle is present and leaf margin is entire (Fig. No. 16c).
Upper epidermis:
The upper epidermal cells have no definite shape. They were polygonal, thin
walled, uninucleate, richly cytoplasmic and variable in size and shape. Cell walls
weresinuous. The upper epidermal cells were measured and length were varied
between 7.22pm to 20.20pm and breadth were varied between 5.27pm to 22.78pm.
82
______________________________ Investigations on epidermal morphology o f leaf
As the leaf was hypostomatic the stomata were totally absent on the upper epidermis
(Fig. No. 16b).
Lower epidermis:
The shape and pattern of lower epidermal cells were quite different than in
the species of Calotropis. These cells have no definite shape. Cell walls were curved
and the cells were much more bigger than in other studied plants. The size o f lower
epidermal cells were observed and found to be varied from 7.28pm to 22.37pm in
length and 5.29pm to 25.94pm in breadth. The type of stomata were found as
Anomocytic or irregular celled type (Fig. No. 16a). Here the actual subsidiary cells
were absent; each stoma was irregularly surrounded by a certain number of cells
which do not differ in size and shape from other epidermal cells. This type of
stomata is called as Ranunculus type.
The stomatal pores were found elliptical and the length were measured as
5.0(±0.67)pm and breadth as 1.25(±0.68)pm. The ratio between the length and
breadth of the stomatal pore were found 4.0. The guard cells also measured and the
length were found as 10.0(±0.21)pm and breadth as 2.8(±0.21)pm. The ratio
between length and breadth of the guard cells were observed as 3.57. The inner wall
of guard cells was found as thick and outer wall as thin. The guard cells were
smaller than those o f other species of Calotropis and also kidney or bean shaped.
Stomata were also scattered all over the lower epidermis. The mean number of
epidermal cells for per microscopic field were found as 407 (±0.11) and the number
of stomata were observed as 52(±0.06). The stomatal index were calculated as
Fig. No. 17 (a-c): Microphotographs of
leaf epidermis in experimental plant
<)5x40x>
(a) Iloya parasitica Wall, upper and
lower epidermis with thick cuticle
(b) Hoyaparasitica Wall, upper
epidermis with few stomata
(c) Hoya parasitica Wall, lower
epidermis with stomata
Fig. No. 18 (a-c): Microphotographs of
leaf epidermis in experimental plant
(J5*40x)
(a) Hoya arnottiana Wight, upper and
lower epidermis with cuticle
(b) Hoya arnottiana Wight, upper
epidermis w ith few stomata
(c) Hoya arnottiana Wight, lower
epidermis with stomata
83
______________________________ Investigations on epidermal morphology o f leaf
11.33% and stomatal frequency were observed as 12.8%. The different features of
the epidermis of Asclepias curassavica Linn, were shown in the Table No.Vm& IX.
6.5
Epidermal morphology of Hoya parasitica Wall.
Hoya parasitica Wall, is an epiphytic creeping plant where the leaves were
found oblong, elliptic, acute exstipulate and stalked. The leaf base was found
rounded or obtuse. Petiole were thick. The lamina were fleshy glabrous and the leaf
surfaces were found rough due to the presence o f short rigid point. Hairs were
absent The leaves were broad indistinctly nerved at the base. The average size of
the leaves were measured and the length and breadth were found as 5 to 12cm. and 2
to 6cm. respectively. The cuticle is entire and very thick due to excessive deposition
o f cell wall substances. The different features o f epidermal cells, cuticle, guard cell
and stomata were shown in the Figure No. 17(a-c) and Table No. (VIII 8c DC).
Upper epidermis:
The upper epidermal cells were polygonal, more or less equal in size, thick
walled and richly cytoplasmic. The cell wall was sinuous. The size of upper
epidermal cells were variable. The average length varied between 6.24pm to
12.56pm and the breadth were found in between 3.9pm to 12.0pm. As the leaves
were amphistomatic, stomata were present on both side o f the leaf. The frequency of
number o f stomata on upper epidermis is very low. On the upper epidermis out of
20,000(±0.27) epidermal cells only 4 (±0.54) stomata were observed (Table
No.Vm). So the stomatal frequency on the upper epidermis were found very low as
0.02% and stomatal index as 0.0199% (Fig. No. 17c).
84
Investigations on epidermal morphology o f leaf
The length of stomatal pore was observed as 7.0(±1.01) pm and breadth was
as 1.25(±0.22) pm. The length by breadth ratio was found as 5.60 on the upper
epidermis.
The guard cells of the upper epidermis were also measured and average
length and breadth were found as 8.0(±0.09)pm and 3.0(±0.18)pm respectively.
Their ratio were found as 2.67.
Lower epidermis:
The shape and pattern of the lower epidermal cells were almost similar to
those of upper epidermis. But the number of stomata were very high than in the
upper epidermis. In Hoya parasitica Wall, the stomatal type or pattern was found as
paracytic or parallel celled type, which were also known as Rubiaceous type of
stomata. The type o f stomata of Hoya parasitica Wall, resembled the stomata of the
species of Calotropis studied (Fig. No. 17b).
On the lower epidermis the mean number of epidermal cells in a microscopic
field were found as 724(±0.19) and the average number o f stomata were found as
42(±0.21). The stomatal index and stomatal frequency for the lower epidermis were
calculated as 5.8% and 5.48% respectively.
The length and breadth of the stomatal pore were found as 7.0(±1.01)pm and
1.5(±0.12)pm respectively. Their length by breadth ratio were found as 4.67. The
guard cells were measured 8.25(±0.22)pm as length and 5.0(±0,12)pm as breadth.
The ratio between these two were found as 1.65. The guard cells were kidney or
bean shaped and the stomatal pore is oval or round in shape (Fig. 17b). Different
features of Hoya parasitica Wall, were shown in the Table No. (VIII and IX).
85
Investigations on epidermal morphology o f leaf
6.6
Epidermal morphology of Hoya arnottiana W ight
Hoya arnottiana W ight is a tall climbing epiphytic plant The leaves were
isobilateral and amphistomatic. Like Hoya parasitica Wall, here also stomata
present on the upper epidermis but very few in number. The leaves were somewhat
bigger than those of Hoya parasitica Wall. The leaves were found broad, oblong to
ovate, elliptic and acute, exstipulate, stalked, petiole long, leaf base or pulvinus was
distinct. The leaves were coriaceous, glabrous and nerves were conspicuous. The
lamina was fleshy and the surface was rough and waxy. The average size of the leaf
were measured and found varied in 7-17cm. long and were 4—7cm. broad.
The cuticle is entire and very thick (Fig. No. 18a).
Upper epidermis:
The upper epidermal cells were polygonal, thick walled more or less like
Hoya parasitica Wall. The average length of upper epidermal cells were varied
between 5pm to 13.66pm and breadth were 2.4pm - 10.0pm. Like Hoya parasitica
Wall, here also very few stomata were found on the upper epidermis (Fig. No. 18b).
Where out of 12,000(±0.22) epidermal cells only 6(±0.22) stomata were found.
Therefore the stomata! frequency and stomatal index on the upper epidermis were
found as 0.05% and 0.0499% respectively.
The measurement of stomatal pore was also taken and the length was found
as 6.25(±0.26) pm and breadth was found as 3.2(±0.22)pm. The ratio between
length and breadth of the stomatal pore was found to be 1.95 on the upper epidermis.
(Table No.VHl)
86
^
_________________________________________
Investigations on epidermal morphology ofleaf
The guard cells of the upper epidermis were also observed and the length and
breadth were found as 7.5(±0.29)jim and 3.2(±0.29)pm respectively. The ratio
between the length and breadth of guard cells were calculated as 2.34.
Lower epidermis:
The cells o f the lower epidermis were almost similar in shape and pattern
with those o f upper epidermis. But number o f stomata on the lower epidermis was
very high as compared to those present in the upper epidermis. The stomatal type
and pattern were found as paracytic or parallel celled type, similar to those present in
Hoya parasitica Wall, and the three species of Calotropis.
The mean number of epidermal cells on the lower epidermis on a
microscopic field were found as 616(±0.16) and the mean number o f stomata were
found as 37(±0.76). The stomatal index and stomatal frequency for the lower
epidermis were calculated as 5.67% and 6% respectively.
The length and breadth of the stomatal pore in the lower epidermis were
found as 6.25(±0.25)pm and 2.5(±0.23)jim respectively and the ratio was found as
2.5. The measure of guard cells were also observed on the lower epidermis o f Hoya
arnottiana Wight, and found the length as 7,0(±1.16)pm and breadth as
2.5(±0.92)|im. The ratio between the length and breadth of the guard cells were
found as 2.8.
The shape of guard cells and stomatal pore were found to be similar with
those o f Hoya parasitica Wall. i.e. kidney or bean shaped guard cells and oval or
rounded stomatal pore.