Vol. 9(12), pp. 457-465, December 2015
DOI: 10.5897/AJPS2015.1306
Article Number: A477DFA56040
ISSN 1996-0824
Copyright © 2015
Author(s) retain the copyright of this article
http://www.academicjournals.org/AJPS
African Journal of Plant Science
Full Length Research Paper
Morpho-anatomical characters of Zehneria capillacea
(Schumach) C. Jeffrey and Zehneria scabra (L.F.) Sond
Cucurbitaceae
Josephine Agogbua, Chimezie Ekeke* and Bosa Ebenezer Okoli
Department of Plant Science and Biotechnology, Faculty of Biological Sciences, University of Port Harcourt,
P.M.B. 5323, Choba, Rivers State, Nigeria.
Received 3 April, 2015; Accepted 12 October, 2015
Comparative studies on macro-morphology, foliar epidermis, stem and petiole anatomy of two
indigenous wild cucurbits (Zehneria capillacea and Zehneria scabra) in Nigeria were carried out in order
to improve the delimitation of the species based on these parameters. The morphological features of
significance observed include variations in leaf and stem pubescence density, leaf shape, fruit shape
and color, flower color, seed shape and coat texture. Similarities were observed in their growth habit,
shape of foliar epidermal cells, stomatal features and stem anatomy. The two species evaluated have a
creeping growth habit, uniseriate eglandular trichomes, anomocytic and tetracytic stomata, pentagonal
shaped stem with 8 bicollateral vascular bundles. Glandular 4-celled head trichome and isotricytic
stoma were only found in Z. capillacea. The leaves of both species are amphistomatic having adaxial
and abaxial stomatal densities of 2.47±0.058 and 13.68±0.021 for Z. capillacea and 3.24±0.125 and
19.72±0.199 for Z. scabra. However, the observed petiolar vascular bundle was 5 in Z. capillacea and 7
in Z. scabra. This distinct number in the petiole provides additional distinguishing information for
maintaining them as different species.
Key words: Anatomy, bicollateral vascular bundles, stomata, trichome.
INTRODUCTION
The genus Zehneria Endl. belongs to sub-tribe
Cucumerinae of the Benincaseae together with eleven
other genera (Jeffrey, 2005) and is presently restricted to
those minor cucurbits with small, white or yellow, mostly
monoecious flowers. There are about 35 species in the
Old World tropics, extending from South Africa and
Madagascar through tropical Africa and Asia to Japan,
Malaysia, Australia and Polynesia (Jeffrey, 1990; De
Wilde and Duyfjes, 2004). Ethno-botanical surveys
showed species such as Zehneria capillacea, Zehneria
cordifolia, Zehneria minutiflora and Zehneria mucronata
in the Niger Delta region of Nigeria (Edwin-Wosu and
Ndukwu, 2008).
In African countries, villagers generally consume leaves,
*Corresponding author. E-mail: ekeke.uc@gmail.com.
Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution
License 4.0 International License
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Afr. J. Plant Sci.
fruits and flowers of cultivated cucurbits and also harvest
leaves and fruits of some wild cucurbits for consumption
and medicinal use (Jansen van Rensburg et al., 2004).
Zehneria species have enormous ethno-botanical value
and are used by different tribes for food as wild edible
plants and treatment of various ailments. In India, the
leaves of wild cucurbits such as Z. maysorensis are
powdered and taken with honey to kill stomach worms
(Ayyanar and Ignacimuthu, 2005). The root extract of Z.
scabra is used with milk to treat fever and diarrhea while
the leaf extract is used to treat skin rashes (Anand and
Jeyachandran, 2003) and has anti-bacterial and antiinflammatory properties. Leaves of Z. scabra and bark
and leaf of Rumex nervosus are pounded and rolled in
cloth, and tied on swelling to reduce the effect (Amenu,
2007).
In Nigeria, roots of Z. cordifolia are used by herbalists
to induce abortion (Chike et al., 2006), while the
powdered leaves of Z. hallii is used for the treatment of
tapeworm and as sedatives (Burkill, 1985). The leaves of
Z. capillacea and Z. cordifolia are used as vegetable in
soup (Edwin-Wosu and Ndukwu, 2008; Omara-Achong et
al., 2012). Despite the immense economic potentials of
cucurbits, information on their morphology and anatomy
is either scanty or completely lacking (Okoli, 2013).
According to Stace (1980), the anatomical
characterization of plants is not affected by environmental
changes and the knowledge has been utilized to delimit
species, genera and families in plant, this study is widely
used in systematic identification, placing anomalous
groups in a satisfactory position in classification and
explaining patterns of relationship that may have not
been clearly expressed in morphological features. Among
Nigerian species of cucurbits, the uses of morphological
and anatomical characters in their delimitation have been
reported (Okoli 1984; Aguoru and Okoli, 2012; Agbagwa
and Ndukwu, 2004; Ndukwu, 1988; Ndukwu and Okoli,
1992; Ajuru and Okoli, 2013). Also, taxonomic,
cytogenetic and ethno-botanical investigations have been
conducted on some of these indigenous cucurbits by
researchers in the Universities and national research
institutes (Okoli, 1984, 1987; Ndukwu, 2000; Ndukwu et
al., 2005; Agbagwa, et al., 2007; Agbagwa and Ndukwu
2004) but reports on the anatomical features of Zehneria
species is lacking.
This study was carried out with the aim of comparing
the morphological and anatomical features of Z.
capillacea and Z. scabra which are two wild cucurbits
with little scientific report and to use these characters to
improve the delimitation of the species.
MATERIALS AND METHODS
taxonomy laboratory of the Department of Plant Science
Biotechnology, University of Port-Harcourt, Choba, Rivers State,
Nigeria (04° 54’ 29.00’’; 006° 55’ 02.90’’).
Plant material
Fresh plant materials of Z. capillacea and Z. scabra were collected
during field trips to various parts of Rivers State, Bayelsa State and
the University of Port-Harcourt environment.
Morphological studies
Standard morphological descriptors for Cucumis germplasm
prepared by The International Plant Genetic Resources Institute
(IPGRI) Italy, was used to score vegetative and inflorescence
characters (IPGRI, 2003). Overall morphology of the leaf, flowers
and fruits were recorded by photography.
Epidermal studies
Foliar materials for epidermal studies were collected fresh from
plants in the field. 5 mm – 1 cm square leaf cuttings were obtained
from identical regions of each fresh leaf, generally from mid-way
between the leaf base and apex of lamina including the mid-rib. The
adaxial and abaxial epidermal peels were obtained using sharp
pointed forceps. Peels were stained with 1% safranin or alcian blue
rinsed with distilled water to remove excess stain and then mounted
in a drop of pure glycerol on clean glass slides. A cover glass was
placed over the drop and sealed with nail vanish to prevent
dehydration (Okoli and Ndukwu, 1992). The epidermal features that
were observed include: organization of the epidermis, arrangement
of the epidermal cells, nature of trichomes, shape of epidermal cells
and nature of the anticlinal cell wall of the leaf epidermis, stomatal
types, density and index. The stomatal index (SI) was estimated
based on Metcalfe and Chalk (1979) while the terminology for the
stomatal type is taken after (Malvey, 2004). The mean and standard
deviation were calculated using Microsoft excel 2010.
Stem and petiole anatomical studies
Specimens for anatomical analysis were obtained fresh from
matured plants and fixed in FAA for 12 h. They were dehydrated,
transferred to 70% ethanol and kept at room temperature until
required. The stem and petiole were hand sectioned using sharp
razor blades (Okoli and Ndukwu, 1992). The sections were stained
in 1% safranin red for two minutes, viewed and micro-photographed
using a photomicroscope.
RESULTS
The summary of the results of this study is presented in
Tables 1 – 3 and Figures 1 – 4.
Habit, habitat and morphology of Zehneria species
Experimental site
The experiment was carried out in the biosystematics and
The species grow in swampy, seasonal flood plain or
moist soils. Z. scabra predominantly grows in sandy
Agogbua et al.
459
Table 1. Morphological characteristics of Z. capillacea and Z. scabra evaluated in the wild.
Species
Descriptors
Growth habit
Stem pubescence
Leaf shape
Leaf color
Fruit shape
Flower color
Primary fruit color
Secondary fruit color
Ripe fruit color
Seed coat
Seed coat texture
Inter-node length (cm)
Petiole length (cm)
Z. capillaceae
Indeterminate
Moderate
Triangular with hastate base
Dark green
Elliptical
White
Green
Dark green
Green
Light brown
Smooth
4-6
2-4
Z. scabra
Indeterminate
Dense
Triangular with cordate base
Green
Oval (Globose)
Yellow
Light green
Dark green
Red
Dark brown
Rough
6-7
3–5
Table 2. Epidermal characteristics of Zehneria capillaceae and Zehneria scabra.
Epidermal character
Z. capillacea
Adaxial
Z. scabra
Abaxial
Shape of epidermal cell
Regular
Irregular
Anticlinal cell wall pattern
Slightly straight or curved
Undulating but partly curved
Stomata type
Anomocytic, tetracytic, isotricytic
Anomocytic, tetracytic
Stomata index (S.I)
2.47±0.058
13.68±0.022
+
+
Trichomes
+
+
Glandular
Eglandular
2 Type
2 Type
Adaxial
Abaxial
Regular
Irregular
Slightly straight or curved
Undulating
Anomocytic, tetracytic Anomocytic, tetracytic
3.24±0.125
19.72±0.199
+
+
1 Types
1 Types
+ = Present; - = Absent.
Table 3. Anatomical characteristics of Zehneria capillaceae and Zehneria scabra.
Anatomical character
Shape
No. of vascular bundles
Nature of adaxial surface
Z. capillacea
Stem
Petiole
5-angled
U-shaped
8
5
NA
U-shaped or curved
Z. scabra
Stem
5-angled
8
NA
Petiole
U-shaped
7
V-shaped
NA = not applicable.
beaches or soils while Z. capillacea grows on moist soil.
The qualitative descriptors scored for morphological traits
in the two species are shown in Table 1. The plant habit
(creeping) was similar for both species (Figure 1).
However, there was phenotypic variation in the
vegetative and reproductive morphology of plants
evaluated. The leaf size of Z. scabra was visually
observed to be bigger in size and more hairy than Z.
capillacea (Figure 1a-d). The flower color is yellow in Z.
scabra and white in Z. capillacea. Other observed
variation include stem and leaf pubescence, leaf shape,
fruit shape, fruit primary and secondary color and seed
coat texture (Table 1 and Figure 1e-f).
Epidermal characters
The result of the leaf epidermal study for the two species
revealed uniseriate epidermis. The two species are
amphistomatic. Three stomata types were observed on
the epidermal surfaces of these species. The stomata
types include tetracytic (stoma completely surrounded by
460
Afr. J. Plant Sci.
Figure 1. Habit and habitat of Z. scabra (a) and Z. capillacea (b). Arrows show the
Zehneria species. Plate 2. Reproductive characters of Zehneria species: (c) Z. scabra
showing yellow flowers, arrow shows ripe red fruit; (d) Z. capillacea showing white
flowers; (e) Fruits of Z. scabra and (f) Fruits of Z. capillacea.
only 4 subsidiary cells, variable in size and shape, of
which two are polar and two are lateral in position),
anomocytic (stoma completely surrounded by only 4 or
more subsidiary cells, variable in size and shape other
than tetracytic and stuarocytic types) and isotricytic
(stoma completely surrounded by only 3 subsidiary cells,
variable in position and shape but 3 of the subsidiary
cells are more or less of equal size) (Table 2). The data
recorded revealed that epidermal characters such as
stomatal density and stomatal index are more on the
abaxial surface than the adaxial surface (Table 2). The
stomatal index on the adaxial surface was 13.7±0.021
and 19.7±0.199 for Z. capillacea and Z. scabra respectively while on the abaxial surface, it was 2.47 ± 0.058
Agogbua et al.
461
Figure 2. Epidermal features of Zehneria species: ((a). Adaxial surface of Z. scabra (x100); (b). Abaxial surface
of Z. scabra (x100); (d). Adaxial surface of Z. capillacea (x40) and (e). Abaxial surface of Z. capillacea (x40).
Note: polygonal shape of the upper epidermis and the irregular crenated shape of the lower epidermis in both
species.
and 3.24 ±0.125 for Z. capillacea and Z. scabra,
respectively. Variations were also observed in the shape
of the epidermal cells. The abaxial cells are irregular,
wavy or crenulated while the adaxial cells are more
regular in shape (Figure 2).
Only uniseriate eglandular trichomes were observed in
Z. scabra (Figure 3a) while uniseriate eglandular and
multicellular glandular trichomes are present on leaf
surfaces of Z. capillacea (Figure 3b-d). The two types of
eglandular trichomes observed on the adaxial surface of
Z. capillacea are a short thick walled eglandular trichome
with an acute tip and a broad multicellular base (Figure
3c) and a short unbranched multicellular trichome (Figure
3d). The latter which is absent on the abaxial surface has
4-celled head, serrated short stalk and a spherical broad
base.
Anatomical characters
The stem anatomy of the two species revealed a
pentagonal-shaped or 5-angled stem with 8 bicollateral
vascular bundles arranged in two major rings (Table 3
and Figure 4a-b). The five peripheral smaller bundles
occur on each angle and alternate with the three bigger
inner bundles which border on the pith cavity. The stem
epidermal cells have uniseriate eglandular unbranched
trichomes. Angular collenchyma cells are present below
the epidermis and a broad band of perivascular fibres in
the cortex.
Transverse section of the petiole showed single layered
epidermis which consists of thin walled cells with conical
uniseriate eglandular unbranched trichomes. It also
revealed a free bundle vasculation pattern arranged in a
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Afr. J. Plant Sci.
a
b
c
d
Figure 3. Trichomes in foliar epidermis of Zehneria species. (a) Unisariate eglandular trichome of Z. scabra
with multicellular base; (b) Unisariate eglandular trichome of Z. capillacea; (c) Eglandular trichome of Z.
capillacea with multicellular base only on adaxial surface and (d) Glandular trichome of Z. capillacea showing
4-celled head.
semi cylinder. There are 5 bicollateral vascular bundles
present in Z. capillacea (Table 3 and Figure 4c) Z. scabra
had 7 vascular bundles (Figure 4d). The abaxial surface
of Z. scabra is V-shaped while that of Z. capillacea is
curved or U-shaped (Figure 4c-d).
DISCUSSION
Most curcubits are dioecious (male and female flowers on
different plants) and rarely monoecious (male and female
flowers on the same plant). For example, Citrullus lanatus
Thunb (watermelon) and Cucurbita pepo L. (pumpkin) are
dioecious (Agbagwa and Ndukwu, 2004), Cucumis
sativus L. (cucumber) are monoecious (Ndukwu, 1988).
Then, there are some special plants like limon-cetriolo,
lemon-cucumber which has staminate (male) flowers but
also hermaphroditic (Ndukwu and Okoli, 1992). Some
cultivars of watermelon have male, female and
hermaphrodite flowers on the same plant (Okoli, 1984).
Flowers are small, white or yellow, monoecious or
dioecious, rarely hermaphroditic. Male flowers are solitary
or few to many in sessile or pedunculate racemiform or
umbelliform clusters. The fruit is solitary or clustered,
globose, ellipsoid or fusiform, red, whitish or green,
smooth, sometimes finely pitted when dry (Hutchinson
and Dalziel, 1954). The seeds are small, elliptic to
broadly ovate in outline, compressed or flat (Hutchinson
Agogbua et al.
463
Figure 4. Anatomical features of transverse section (TS) of Z. capillacea and Z. scabra: (a) Stem of Z.
scabra; (b) Stem of Z. capillacea; (c) Petiole of Z. scabra (V-shape of abaxial surface) and (d) Petiole of Z.
capillacea (curved or U-shape of abaxial surface) Note: 5-angled (pentagonal) stem with similar vascular
bundles (a and b) and the variation in the petiole anatomy and number of vascular bundles (c and d).
and Dalziel, 1954; Okoli 1984; Ndukwu, 1988; Ndukwu
and Okoli, 1992; Jeffrey, 1990).
The variations that exist between the two species of
Zehneria is of taxonomic value as observed in this study.
The plant trailing growth habit, ecology, habitat and the
vegetative morphological traits described are consistent
with the description reported by Jeffrey (1990) but in
contrast with the color of Z. capillacea fruits which was
reported as red instead of green as observed in the
current study. Z. scabra occurred predominantly in sandy
soils while Z. capillacea can grow in any soil type.
The leaves of the species are amphistomatic with
anomocytic, tetracytic and isotricytic types of stomata.
Anomocytic type of stomata was the dominant stomata
type observed in the species. It has been described in
many plant species of the Cucurbitaceae (Okoli, 1989)
and it is the most common in angiosperms. However,
isotricytic stoma was found only on the adaxial epidermal
surface of Z. capillacea. This feature is distinctive and
can be used to distinguish among the species studied.
Furthermore, there are more stomata on the abaxial than
the adaxial surface. This is expected since is in line with
reports of Adebooye et al. (2012) on Trichosanthes
cucumerina. A type of uniseriate eglandular trichome and
one type of glandular trichome with 4-celled head were
identified in Z. capillacea while only uniseriate eglandular
trichome was observed in Z. scabra. The occurrence and
types of these trichomes could be used to distinguish the
species. For instance, the 4-celled head glandular
trichome was only observed on the abaxial surface of Z.
capillacea. Also, uniseriate eglandular trichome was
found in both species but the ones in Z. capillacea are
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Afr. J. Plant Sci.
short and thick, while the ones in Z. scabra are long and
thin. This is consistent with the different types of
glandular and eglandular trichomes that have been
studied and described in cucurbits (Okoli, 1989; Kolb and
Muller, 2004; Aguru and Okoli, 2012; Agbagwa and
Ndukwu, 2001).
Morphology of plants is an important factor used in
making useful taxonomic conclusion about plants but it
cannot be solely used. Anatomical feature is also of great
importance in taxonomy since they are less affected by
environmental factors. In this study, the fruit shape and
size, the vascular system of the petiole, the presence of
isotricytic stoma and trichome types are all diagnostic.
The diagnostic features of the two species of Zehneria
therefore as belonging to the family Cucurbitaceae
include the presence of bicollateral vascular bundles and
arrangement of the vacsular bundles in two rows. The
observed anatomical similarities among the Zehneria
species studied indicate phylogenetic relatedness of the
taxa. The anatomical differences observed in each specie
must have been as a result of evolution, conferring
heritable variation that could be exploited for taxanomic
purposes.
Conclusion
Two species share the same ancestral gene pool as they
have most characteristics in common. Based on
anatomical features, the two species of Zehneria studied
can be distinguished from one another based on
morphological traits and variation in the number vascular
bundles present in the petiole. This information is useful
in identification and authentication of the species.
Conflict of Interests
The authors have not declared any conflict of interest.
ACKNOWLEDGEMENT
The author wish to appreciate the assistance and
contributions of the laboratory staff of the Department of
Plant Sciecne and Biotechnology, University of Port
Harcourt for providing enabling environment for the
success of this research work.
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