54162 Otoide, J. E. et al./ Elixir Bio Tech 140 (2020) 54162-54166 Available online at www.elixirpublishers.com (Elixir International Journal)

Bio Technology

Elixir Bio Tech 140 (2020) 54162-54166 Studies on the Leaf Epidermis and Midrib of Some Species of Schreb. in Nigeria Otoide, J.E.*1, Ihinmikaiye, S.O.2 and Otoide, T.F3 1 Department of Science and Biotechnology, Faculty of Science, Ekiti State University, Ado-Ekiti. 2 Department of Biological Sciences, Faculty of Science, Federal University, Otuoke, Bayelsa State. 3 Science Education Laboratory, Department of Science Education, Faculty of Education, Ekiti State University, Ado-Ekiti.

ARTICLE INFO ABSTRACT The leaf epidermis and midrib of Vernonia amygdalina, V. cinerea, V. perrottetii and V. Article history: adoensis were studied following standard procedures and features were observed with the Received: 13 January 2020; aid of compound microscope. To the authors’ knowledge, the leaf and midrib anatomical Received in revised form: features of V. adoensis and V. perrottetii are being comprehensively and adequately 27 February 2020; documented for the first time. The results obtained revealed that the four species were Accepted: 7 March 2020; hypoamphistomatic with anomocytic type of stomata. Stomata Index (%) was higher at the lower epidermis than the upper epidermis with V. amygdalina having 35.00 as the Keywords highest and V. perrottetii having 31.00 as the lowest. Similarly, the highest width (µm) of Epidermal cells, stomata was found in the upper epidermis of V. adoensis having an average of 73.22 ± Bundles, 21.77 while the lowest was 22.46 ± 2.47 as found in the lower epidermis of V. adoensis. Vernonia, Highest stomata length (µm) of 81.46 ± 22.38 was also recorded in upper leaf epidermis Leaves, of V. adoensis while lowest length of 30.43 ± 4.26 was recorded in its lower epidermis. µm, In the four species, epidermal cells were predominantly irregular in shapes with Anomocytic. predominantly sinuous anticlinal and periclinal walls. In another vein, the midribs were oblong in outline consisting of collateral and open bundles arranged in ring-like pattern except in V. perrottetii in which the bundles were concentric, amphicribral, collateral and close. Based on the overwhelming similarities that existed among the four taxa, it was established that there exist interspecies relationship among them. In conclusion, it was opined that the minor and discontinuous differences in the anatomical features of the four species are insufficient to adjudge their rearrangement and repositioning to separate and that their present taxonomic status are unbiased and warranted. © 2020 Elixir All rights reserved.

Introduction infusion is taken for stomach-pains and for tuberculosis and According to Kemka-Evans et. al. (2014), Vernonia fresh roots sliced and cooked with milk and flour for Schreb. belongs to the tribe Vernonieae of the family gonorrhoea. The Sukuma cut up and soak the fresh roots for a (Compositae). The family Asteraceae is the short time in water which is used to wash white blotches, largest family of the flowering , comprising 950 genera, which feel a little ‘soapy’, on the skin of children (Burkill, and 23,000 species. Olorode (1984) noted that the family 1985). Vernonia perrottetii. Sch. Bip. is an erect much Asteraceae possesses simple leaves with alternate or opposite branched annual herb measuring about 24-48cm or more in leaf arrangement. Among the species found in Nigeria, V. height . The leaves are linear to lanceolate in shape and cinerea (L) Less, V. amygdalina Delile and V. conferta measures up to 5mm broad. The flowers are companulate and Benth. form an interesting group to study because V. cinerea measures between 1-1.5cm long (Hutchinson and Dalziel, is a herbaceous weed while V. amygdalina is usually treated 1963). as a shrub and also occur as bitter leaf and non-bitter leaf According to Otoide and Ifedele (2019) the variety and V. conferta is a small tree. The existence of V. morphological characters of angiosperms have been amygdalina in bitter leaf and non-bitter leaf form, sometimes extensively used both for producing classification and for poses a problem in classification of the species as V. diagnostic purposes. These characters are indispensable as amygdalina (non-bitter leaf) is usually regarded as a different they play important roles in plant . The species. V. adoensis is a shrub which grows up to 2 m high. morphological characters do not undermine the importance of It is commonly found in the savanna regions of Senegal and other characters like anatomical and palynological which North and Southern parts of Nigeria, and extending across have been helpful in their own ways; the greatest advantage to Ethiopia. The leaves are used in Kenya by the Masai of the morphological characters is that they can be easily crushed in cold water and applied to cattle sores caused by observed in the field (Singh and Jain, 1991). There are a large ticks. The root is prepared in Northern Nigeria into a bitter number of anatomical characters of taxonomic importance medicine and is used as a digestive and appetizer. In Southern pointed out by Metcalfe and Chalk (1950) and Van Cotthem Nigeria the root is a chew-stick. In Tanganyika a root- (1970). Some of these important anatomical characters are:

Tele: E-mail address: [email protected] © 2020 Elixir All rights reserved 54163 Otoide, J. E. et al./ Elixir Bio Tech 140 (2020) 54162-54166 trichomes, stomata and epidermis. Trichomes have been concluded that the features were sufficient enough to delimit employed very frequently for taxonomic comparisons them from one another. because of their diversity, their universal presence in the Kemka-Evans et. al., (2014) studied the leaf epidermis of angiosperms and their simple means of preparation. For the three species of Vernonia and reported the occurrence of epidermis, shape of the cells, thickness and characteristics of contiguous stomata and sinuous anticlinal walls on the their walls, nature of the sculpturing on their walls as seen in abaxial leaf surface of non-bitter variety of V. amygdalina surface view and inclusions of epidermal cells provide useful and on both leaf surfaces of V. cinerea. Also reported were taxonomic criteria (Nwankwo and Ayodele, 2017). According irregular T- Shaped trichomes on the leaf surfaces of V. to Das and Mukherjee (1997) mature morphological features amygdalina and the cuticular striations on the adaxial surface are the conventional criteria used to establish taxonomic of the same taxa. They concluded that the features were of status. Similarly, Edeoga and Eboka (2000) observed that the taxonomic importance in determining the relationship among use of leaf epidermal morphology in systematics is becoming the species. Furthermore, Gupta et. al., (2017) reported the popular just as the use of other markers like DNA sequence, presence of anomocytic and diacytic stomatal types of chemical compositions, histochemical attributes and uniseriate and biseriate layers of epidermis on the upper and presence/absence of several groups of secondary metabolites. lower leaf surfaces of Alternanthera sessilis respectively. To this end, curious researchers over the years have made Whereas, uniseriate layer of epidermis occurred in both several scientific reports about the features in the epidermis epidermis of A. pungens with only anomocytic stomatal type. of leaves of both dicots and monocots with respect to their They concluded that the leaf anatomical features observed on usefulness and reliability as diagnostic characters in plant the species would be useful in confirming the authenticity of identification and delimitation of taxa. Consequently, the raw drugs resulting from leaves of the two species. Similarly, reports of Edeoga and Eboka (2000), Jayeola and Thorpe Nwankwo and Ayodele (2017) studied the taxonomy of the (2000), Edeoga and Otoide (2001), Nwachukwu and Mbagwu genus Indigofera Lin in Nigeria and reported anisocytic and (2007), Aworinde, et. al. (2013), Kemka-Evans (2014), paracytic stomatal types common in all the species. Also Gupta, et. al., (2012), Nwankwo and Ayodele (2017) and reported were irregular epidermal cell shapes on both surfaces Otoide and Ifedele (2019) are pertinent references. of all the species except in I. capitata, I. nummulariifolia and Edeoga and Eboka (2000) studied the morphology of the I. oblongifolia in which they are polygonal. And that leaf epidermis of some Dissotis species and reported the anticlinal wall patterns were curved, sinuate and undulate in presence of paracytic stomatal type on the abaxial and adaxial all the species. They concluded that the stomatal type and surfaces of all the taxa except in Dissotis rotundifolia where epidermal cell shapes are significant in the taxonomy of the the stomata were anomocytic and variations in epidermal genus Indigofera. cells architecture ranging from pentagonal to polygonal in all Akinnuubi et al. (2013) discovered 2-3, bicollateral the species except in Dissotis rotundifolia where they were vascular bundles in petiole anatomy of Vernonia amygdalina sinuous and irregular. They recommended the usefulness of and 3 oval shaped amphicribal vascular bundles in their observations in the systematics of the genus. Similarly, cinereum (Kemka-Evans, 2017). Anatomical Jayeola and Thorpe (2000) studied the Calyptrochilum with features are widely used in systematics for identification, the aid of microscope. They reported that Calyptrochilum placing anomalous groups in a satisfactory position in chrystyanum was characterized by a network of horizontal classification and for indicating patterns of relationship that grooves, dome shaped micropapillae and a mass of soft wax, may have been obscured by superficial convergence in while C. emarginatum was distinguished by the presence of morphological feature. In the recent past, plant species have densely overlapping conical and globular types of been removed from their family or genera and classified micropapillae. They concluded that sculpturing features in the under another taxon based on anatomical evidence. genus were characteristic and therefore of utility in Characters that are not influenced by environmental factor identifying even sterile specimens and fragments. In the same have proved to be of systematic value (Okoli, 1987). vein, Edeoga and Otoide (2001) reported the characteristics Anatomical characters have been widely used by many of leaf epidermal morphology of Amaranthus dubius, A. workers in taxonomy such as (Stace 1980) vividly showed hybridus, A. lividus, A. spinosus, A. tricolor and A. viridis that the bundle sheath in Telfairia occidentalis Hooker Fil is that irregularly shaped epidermal cells were observed in A. thin–walled and sclerenchymatous while that of T. pedata dubius while rectangular or polygonal epidermal cell shapes, (Sims) Hooker is thin walled and parenchymatous, thus paracytic stomata and calcium oxalate crystals were observed helping to clarify the taxonomic relationship of these two in A. tricolor and A. lividus. These authors were the first to species. Isawumi (Isawumi, 1984) described the shape of leaf report and document the leaf epidermal characteristics of A. trichomes of sixty species of Vernonia indicating the presence dubius, A. lividus and A. tricolor. Furthermore, Nwachukwu of T – shaped type of trichomes in V. amygdalina and and Mbagwu (2007) reported variation in shape of epidermal V.conferta and uniseriate trichomes in V. cinerea. Maryam et cells- mostly rectangular and sinuous in Indigofera pulchra, I. al. (2013) used the stem epidermis diameter, cortex diameter, senegalensis and I. stenophylla while it varies from palisade diameter, parenchyma diameter, the vessel-to pentagonal in I. paniculata, I. prieureana and I. terminalis epidermis diameter, stem-to-epidermis diameter, rupture of though hexagonal in I. hirsuta and I. tinctoria. Similarly, pith, width of vessels, inner phloem diameter, stem diameter, Aworinde (2013) compared the leaf architecture of some and stem-to-vessel diameter to evaluate the species Vernonia species in south western Nigeria. He reported the relationship in the genus Anchusa. occurrence of wavy anticlinal wall with polygonal cell shape Methods in V. ambigua and straight anticlinal wall with irregular cell Collection of plant samples shape in V. amygdalina and V. cinerea. Paracytic stomatal Matured fresh leaves of Vernonia amygdalina, V. cinerea types were also reported about the leaves of the genus. He were collected from Ekiti State University environs while V. perrottetii and V. adoensis were collected from along 54164 Otoide, J. E. et al./ Elixir Bio Tech 140 (2020) 54162-54166 Iworoko-Ifaki road all in Ekiti State, Nigeria. Ekiti State Results and Discussion University is on geographic coordinates of 7.71410N, The anatomical features in the leaf epidermis and midrib 5.26010E. Iworoko is on 7044’0’’North, 5016’0’’East. Ifaki on of the species have been summarized in Tables 1 and 2. the other hand, is on 7.78000N, 5.24230E. The specimens The shapes of the epidermal cells were irregular in the were then taken to the Herbarium of Ekiti State University, lower and upper leaf epidermis in all the species except in Ado- Ekiti for authentication. Vernonia amygdalina and V. perrottetii which showed Sectioning of the leaves hexagonal and polygonal shapes in the upper leaf epidermis The transverse sections of the leaves of the four different (Table 1). The anticlinal and periclinal epidermal cell walls in taxa were made following the methods of Kemka- Evans et. both upper and lower leaf epidermis were sinuous in all the al; (2017). Sections were cut with the aid of a rotary species except in the upper leaf epidermis of V. amygdalina microtome between 15-18 microns and placed on the clean where the walls were slightly straight. slides smeared with a thin film of Hauptis albumin. The slides Trichomes were present in both upper and lower leaf were placed on hot plates at 40°C for a few minutes to allow surfaces of all the species except in the upper leaf surface of the ribbons to expand and kept in an oven at 30°C for 2 V. amygdalina. The trichomes were short, uniseriate and hours. The slides were immersed in pure xylene for 2-5 scanty. Long trichomes were however observed in the upper minutes and in a solution of xylene and absolute alcohol with and lower leaf epidermis of V. adoensis. a 1:1 ratio (v/v) for few minutes. The slides were stained with The width of stomata at the upper leaf surfaces were methylene blue for 30 minutes. The specimens were 35.24 ± 7.10, 29.35 ± 0.10, 29.33 ± 4.81 and 73.22 ± 21.77 dehydrated in acid alcohol. (1m1 of concentrated HCl to 99 for V. amygdalina, V. cinerea, V. perrottetii and V. adoensis ml of 70% alcohol). The section were washed in 70% alcohol respectively, whereas, at the lower leaf surfaces the width and left in running water for about 10 minutes. Counter- were 34.61 ± 6.17, 23.99 ± 2.11, 29.98 ± 3.39 and 22.46 ± staining was done with 50% safranin-O for two minutes, then 2.47 respectively. The lengths of stomata on the other hand, dehydrated in alcohol, xylene-absolute alcohol solution and were 53.20 ± 7.60, 36.35 ± 1.63, 42.62 ± 6.31 and 81.46 ± pure xylene at intervals of few seconds and mounted in 22.38 for the upper leaf epidermis of V. amygdalina, V. canada balsam. cinerea, V. perotetti and V. adoensis respectively, whereas, at Peeling of epidermis the lower leaf epidermis they were 52.18 ± 7.88, 31.31 ± Epidermal peels of both upper and lower surfaces of the 5.97, 44.18 ± 5.70 and 30.43 ± 4.26 respectively (Table 1). leaves of the four different taxa were made following Kemka- Scanty stomata were observed at the upper leaf epidermis Evans et. al. (2014). The materials fixed in F.A.A. (Formalin of all the species as expressed in their Stomatal Index (SI). acetic acid alcohol mixture) for 48hours materials were rinsed The Stomatal Index (%) at the upper epidermis were 15.00, with distilled water and soaked in commercial bleach 11.00, 13.00 and 14.00 for V. amygdalina, V. cinerea, V. (Sodium Oxochlorate (II) (NaCIO)) for 24hours to clear the perrottetii and V. adoensis respectively. Conversely, stomata epidermis and loosen the tissues, The two surfaces were tissues were abundant at the lower leaf surfaces of the four carefully separated using a razor blade and finally stained spsecies as Stomatal Indexes of 35.00, 32.00, 31.00 and 30.00 with safranin-O. The epidermal strips were then mounted were derived for V. amygdalina, V. cinerea, V. perrottetii and temporarily on clean slides in 50% glycerin and covered with V. adoensis respectively. cover slips. The length and breadth of 30 stomata and Idioblasts were observed at the lower epidermis of V. epidermal cells were measured on both surfaces. Ten cinerea and V. adoensis but absent in both leaf surfaces of V. microscopic fields chosen at random were used for perrottetii. They were also absent at the lower leaf surface of enumeration of number of stomata and epidermal cells V. amygdalina and upper leaf surface of V. adoensis and V. appearing per field view. The stomatal index and frequencies cinerea. were calculated according to the formula of Salisbury in In another vein, the number of vascular bundles in the Olorode (1990) using the formula Stomatal Index = S/E+S x midribs of V. cinerea, V. adoensis and V. amygdalina were 100/1 where S = number of stomata per unit area, E = number 3-4, 5-6 and 3-4 units respectively, and they were arranged of epidermal cells in the same area. in a ring-like pattern in the vascular cylinder except in V.

Table1. Leaf Epidermal Features of the Vernonia Species. Species S/n Parameters A B C D 1 Shape of Epidermal Cells U: Polygonal – U: Irregular U: Polygonal U: Irregular Hexagonal. L: Irregular L: Irregular L: Irregular L: Irregular 2 Nature of Epidermal Cell Wall U: Slightly straight U: Sinuous U: Straight U: Sinuous L: Sinuous L: Sinuous L: Sinuous L: Sinuous 3 Type of Trichomes U: Absent U: Short and uniseriate U: Short, uniseriate U: Scanty, long and uniseriate L: Short, septate, L: Short, and uniseriate and scanty L: Long, numerous and uniseriate Aseptate and L: Short, uniseriate scanty and scanty 4 Type of Stomata U: Anomocytic U: Anomocytic U: Anomocytic U: Anomocytic L: Anomocytic L: Anomocytic L: Anomocytic L: Anomocytic 5 Stomata Index (%) U: 15.00 U: 11.00 U: 13.00 U: 14.00 L: 35.00 L: 32.00 L: 31.00 L: 30.00 6 Stomatal Length (µm) U: 53.20 ± 7.60 U: 36.35 ± 1.63 U: 42.62 ± 6.31 U: 81.46± 22.38 L: 52.18 ± 7.88 L: 31.31 ± 5.97 L: 44.18 ± 5.70 L: 30.43 ± 4.26 7 Stomatal Width (µm) U: 35.24 ± 7.10 U: 29.35 ± 0.10 U: 29.33 ± 4.81 U: 73.22 ± 21.77 L: 34.61 ± 6.17 L: 23.99 ± 2.11 L: 29.98 ± 3.39 L: 22.46 ± 2.47 8 Idioblast U: Numerous U: Absent U: Absent U: Absent L: Absent L: Numerous L: Absent L: Numerous KEY: A= Vernonia amygdalina Del; B= V. cinerea (L.) Less; C= V. perrottetii. Sch. Bip; D= V. adoensis Sch. Bip 54165 Otoide, J. E. et al./ Elixir Bio Tech 140 (2020) 54162-54166 Table 2. Anatomical Features Of The Midrib Of The Vernonia Species. Species S/n Parameters A B C D 1 Number of vascular Ring-like Ring-like Single unit Ring-like bundles (3-4 units) (5-6 units) Concentric amphicribral (3-4 units) 2 Shape of midrib Oblong Oblong Oblong Oblong 3 Nature/type of vascular Collateral and open Collateral Collateral and Collateral and bundles and open Close open 4 Epidermal hair Uniseriate and numerous Long, unicellular and Short and uniseriate Short, uniseriate and scanty numerous 5 Orientation of Straight Straight Straight Straight epidermis 6 Ergastic substances - Starch grains - Druses 7 Mesophyll Palisade and Palisade and Palisade and Palisade and spongy Spongy spongy Spongy KEY: A= Vernonia cinerea (L.) Less; B= V. adoensis Sch. Bip; C= V. perrottetii Sch. Bip; D= V. amygdalina Del

perrottetii where it was a single unit, concentric and References amphicribral in nature. Collateral and open vascular bundles Akinnubi, F.M, Akinloye, A.J and Oladipo, O.T. (2013). were observed in the midrib of the four species except in V. Petiole anatomy of some species of Asteraceae in Southwest perrottetii where the bundles were the collateral and closed Nigeria. Academic Journal. 7(12): 608-612. type. Furthermore, Uniseriate and short epidermal hairs were Aworinde, D.O., Ogundairo, B.O. and Erinoso, S. M. (2013). observed in all the four species (Table 2). The outline of the Comparative leaf architectural studies of some Vernonia midribs were oblong for all the species. Ergastic susbtances Schreb (Asteraceae) in Nigeria. Current Botany. 4 (3): 43-47. such as starch grains and druses were observe in the Burkill, H.M. (1985). The Useful Plants of West Tropical parenchyma cells of the midribs. Africa, Vol. 1, AD Royal Botanic Gardens Kew. The Results obtained from the present study revealed that the Whitefriars Press Ltd., London. leaves were hypoamphistomatic with respect to distribution Das, S. and Mukherjee, K. K. (1997). Morphological and of stomata. Anomocytic type of stomata were observed at Biochemical Investigations on Ipomea Seedlings and their both leaf surfaces. These observations are in line with the Species Interrelationships. Annals of Botany. 79, 565-571 previous reports of Kemka-Evans et al. (2014) on three Edeoga, H.O. and Eboka, A.U. (2000). Morphology of the species of Vernonia such as V. cinerea, V. amygdalina and V. leaf epidermis and systemics in some Dissotis Benth. Species conferta. (Melastomataceae). Global J. Pur. Appl. Sci. 6, 371-374 To the authors’ knowledge there is little or no Edeoga, H.O. and Otoide, J.E. (2001). Characteristics of Leaf comprehensive information on the anatomical features of the Epidermal Morphology of some Amaranthus Species leaves of V. adoensis and V. perrottetii in circulation. Hence, (Amaranthaceae) in Nigeria. New Botanist. XXVIII: 183-194 it suffices to assert that the present reports are being Gupta, H.C., Raj, J., Rathi, A., Sundaram, E.N., Kumar, S. comprehensively and adequately documented for the first and Manchanda, R.K. (2012). Morpho-anatomy of leaf, stem time. and root of Alternanthera sessilis (L.) R. Br. Ex DC and Consequent upon the above, it suffices to state Alternanthera pungens Kunth (Amaranthaceae) and its categorically that there were very minor and discontinuous significance in drug identification. Indian Journal of Research differences in the anatomical features in the leaves and in Homoeopathy. 6(4), 1-7. midribs of the four Vernonia species. Worthy of note is the Hutchinson, J. and Dalziel, M.D. (1963). Floral of West occurrences of single concentric and amphicribral as well as Tropical Africa (II). Crown Agents, London. Pp.271-283 collateral and closed bundle type only in V. perrottetii. Isawumi, M.A. (1993). New Combination in Baccuaroides Although these features are diagnostic, they are insufficient to Moench (Vernonieae; Compositae) in West African. Feddes adjudge its regrouping to another genus. The similarities Reportorium 104: 304-326. among the species with respect to the features observed are Jayeola, A. A. and Thorpe, J.R. (2000). A scanning electron overwhelming. Hence, there is interspecific relationship microscope study of the genus Calyptrochilum KRAENZL. among the four taxa. () in West Africa. Feddes Repertorium. III (5-6), In the light of the foregoing, it is pertinent to state that 315-320. the present taxonomic hierarchy and status of these species in Kemka-Evans, C.I., Okoli, B. and Nwachukwu, C. (2014). the genus Vernonia is unbiased and warranted. Although at Epidermal studies of three species of Vernonia Schreb. in present the taxonomic position of the species is not under Southern Nigeria. BIODIVERSITAS. 15(2), 137-141 criticisms, there may be the need to explore other sources of Kemka- Evans, C.I, Okoli, B., Nwachukwu, C.U. and taxonomic inferences such as Cytology, Taximetrics, Ikeanumba, M (2017): Anatomical Studies on the Stem and Ecology, Biogeography and Molecular biology for more Leaf of Vernonia Amygdalina Del, Cyanthillium cinereum information and evidences to further consolidate and (L.) H. Rob and Brenandendron donianum (DC.) H.Rob. in substantiate the present taxonomic status of the species or Southern Nigeria. Journal of Applied Life Sciences suggest their possible regrouping (especially V. perrottetii) International. 15(4): 1-8 when necessary. Metcalfe, C.R. and Chalk, L. (1950). Anatomy of Dicotyledons. Clarendon Press, Oxford. 1500pp.

54166 Otoide, J. E. et al./ Elixir Bio Tech 140 (2020) 54162-54166 Maryam, K; Fatemeh, N and Masoud, S. (2013). Stem and Olorode, O. (1984). Taxonomy of West Africa Flowering fruit anatomical study of the Anchusa species (Boraginaceae) Plants. Longman, Iondon. in Iran. Phytologia Balcanica. 2013;19 (2): 193–199. Otoide J.E. and M.O. Ifedele (2019): Leaf Epidermal Nwachukwu, C.U. and Mbagwu, F. N. (2007). Leaf Anatomy Charateristics of Some Alternanthera Species in Nigeria. of Eight Species of Indigofera L. Agricultural Journal. European Modern Studies Journal. 3(3):44-54 2: 149-154 Singh, V. and Jain, D.K. (1991). Taxonomy of Angiosperms. Nwankwo, O.E and Ayodele, A.E. (2017). Taxonomic A Text book for University Press. New Delhi , 74- Studies of the Genus Indigofera Linn. in Nigeria. IDOSR 120pp. Journal of Scientific Research. 2 (3): 10-26 Stace, C.A. (1980). Plant taxonomy and biosystematics. Okoli, B.E. (1987) Anatomical studies in the leaf and London Edward Arnold.74–134. probract of Telfairia (Cucurbitaceae) Feddes Reportorium. Van Cotthem, W.R.J. (1970). A classification of stomatal 102:183-187. types. Bot. J. Linn. Soc. 63, 235-246.