|Home Instructors Journals ContactUs|
The use of vegetative and floral morphology in the systematic grouping, characteristics and classification of different taxa is no more a new event. For example, Pandey (2000) used morphological features in recognition of two Solanaceae subfamilies of solanoideae and cestroideae.Edeoga et al (2000) used vegetative and floral characteristics to classify some species of Dioscorea.
Similarly, Mbagwu and Edeoga (2006) did similar work in 8 Vigna species. Further more, Nwachukwu and Okeke (2001) used morphological characters in the characterization of Maesobotrya, barteri var bateri. Equally important is the pollen morphology. Study of pollen grains has been very helpful in assigning the status of plant since pollen grain wall has specific characters.
Journal of Research in National Development 6(2) December, 2008
An excellent review of the systematic application of palynology is given by Erdtman (1952) and good examples of the use of pollen in systematic studies are given by Agwu and Beug (1982), Cowan (1969) in genus Swartzia, Edeoga et al (1996).
Economically members are used in the production of drugs e.g. pharmaceutical steroids. The leaf juice is used in treating inflammation of the kidney and bladder and in gonorrhoea, dropsy, heart diseases. Bile and enlargement of the spleen, Pandey (2000).Pollen grains on the other hand have been used by forensic experts in criminal cases.
Despite the numerous economic and agronomic importance of the Solanum species, there is absence of clear taxonomic criteria especially in the morphology and palynology to delineate these taxa. Hence, the objective of this study is to provide detailed morphological and palynological information on the two Solanum species for accurate description and proper identification of the species.
Materials and Methods
collections was made from different locations in both Imo and Anambra states such as Egbeada, Okigwe, Akokwa, Umuchu and Achina.The length and width of the leaves were measured using a 30cm meter rule. This was done by spreading the middle leaflet on a flat surface of a laboratory bench. For the width, the same median leaflet was chosen to avoid being biased.
For the pollen study, pollen grains from each species were collected by tearing out fresh and mature flowers of these floral on a slide. Samples were made on fresh flower from September to October 2007 at the science laboratory of University of Nigeria, Nsukka.Samples for the light microscope were acetolysed following slight modifications (Erdtman, 1996).Unstained, acetolysed pollen grains were mounted on slides and covered with a zero size cover slip, sealed with nail polish. The photomicrographs of pollen grains were taken from the slides using a LEITZ WETZIAR ORTHOLUX microscope fitted with a vivitar-V335 camera.
Table 1 a: Vegetative Morphology of S. melongena and S.nigrum.
Table 1 b: Floral Morphology of the two Solanum species studied
CHARACTERS S.melongena S.nigrum
(a) (b) Fig. 1: Morphology of (a) S. melongena (b) S. nigrum
The results of the vegetative features of the two species studied showed that the species share certain morphological characteristics in common. These include habit (herb), leaf type, shape (ovate), margin, venation, leaf base (obtuse) e.t.c .Table 1 a, 1 b, fig. 1 and 2. In contrast, the stem bark of S. melongena is grey while that of S.nigrum is green in colour. The texture of S.melongena is hairy while that of S.nigrum is smooth. The leaf apex of S.melongena is long acuminate with broad leaves while that of S. nigrum is short acuminate with small leaves.
Table 2: Palynomorphological features of two Solanum species studied.
The pollen grains of the two Solanum species studied showed similarities in their pollen attributes of wall sculpture, aperture, and symmetry e.t.c. Table .2 However, the greatest variation observed in pollen morphology of the Solanum species lies in the size of their pollen wall. The greatest thickness of the exine (2.15µm) was observed in S.melongena while 1.65µm was recorded in S.nigrum.This observation reported for the first time could be of taxonomical importance.
species studied constitutes an important distinguishing factor that could be used for establishing intraspecific relationship. Solanum melongena grows up to the height of 90-150cm while that of Solanum nigrum range between 70-120cm.S.melongena is much branched and hairy when compared to that of S.nigrum which is less branched and smooth. The leaf apex of S.melongena is long acuminate with bigger fruits unlike that of S.nigrum that is short acuminate with small fruits. This confirms the works of earlier research findings of Benson, 1957; Schipper, 1996; Mbagwu and Edeoga, 2006; Nwachukwu and Mbagwu, 2006; who used morphological variations in taxonomic characterization of plants.
Despite their numerous differences, the two species show similarities in some respects such as habit, leaf type, arrangement, floral symmetry, sepal and petal numbers e.t.c .as shown in Table 1 a, this is in line with the work of Nwachukwu and Edeoga who used floral similarities in the genus Indigofera in establishing intraspecific relationship among species. Similarly, the pollen morphology of the two species of Solanum studied showed slight variations. It was observed that the pollen grain of S.nigrum is small in size (1.65µm) when compared with that of S.melongena (2.15µm).This variation in size may be due to indiscriminate mating leading to hybridization which may be operating in this complex. This is not surprising since previous workers have made similar observations in other groups of angiosperm (Bonnefille and Riollet, 1980; Moore and Webb, 1978; Agwu and Osibe, 1992; Anozie, 1985; Agwu and Beug, 1982).
The pollen shape expressed as the ratio of the length of polar axis to that of equatorial dimension (Erdtman, 1952), is found to be more or less quinquangular in polar view and elliptic in equatorial view in both species. Further more, similarities are found in aperture type (tricolporate), pollen shape (sub spherical) and wall struchcture (scabrate) of the pollen grain of the two Solanum species studied.
The results of the morphology and palynology of the two species of Solanum studied have proved to be of immense assistance in interpreting problems related to plant classification. The results could therefore be utilized with information from other discipline in clarifying taxonomic relationships of these taxa with other genera, species or subspecies.
Agwu, C.O.C. and Osibe, E.E. (1992): Air borne Palynomorphs of Nsukka during the months of February- April (1990). Nigerian Journal of Botany, 5:117-185
Anozie, G.A. (1985): Pollen analysis of water and sediments from Lake Nguru, Nsukka.B.Sc Thesis. University of Nigeria, Nsukka.pp .29
Bonnefille, R. And Riollet, G. (1980): Pollen des savannes de Afrique Orientale.Edition du CNRS.Paris
Benson. L. (1957): Plant classification. Lexington: D.C Heath and Company.pp.221-226
Cowan, R.S. (1969): Harleyodendron, a new genus of Leguminosae (swartzieae).Brittonia.31:72-78
Edeoga, H.O; Ogbelor, N.O.and Anayo, (1996): Pollen morphology of Nigerian species
of Anenlema R.Br and Ludwigia L. New Botanist.23:223-231
Erdtman, G. (1952): Pollen morphology and Plant taxonomy of Angiosperm.Walthan Mass Herfner Press.p.515
Mbagwu, E.N and Edeoga, H.O. (2006): Morphology of vigna species (Leguminosae) Medwell.Agricultural Journal.1.vol.2:200-205
Moore, P.D and Webb, J.A. (1978): An illustrated Guide to Pollen Analysis . Bungay. Chaucers Press.
Nwachukwu, C.U and Mbagwu, E.N. (2006): Anatomical studies on the petiole of some
species of Indigofera.Medwell.Agricultural Journal.1.vol.2:255-258
Nwachukwu, C.U and Okeke, S.E. (2001): Characterization of Maesobotrya barteri var bateri.Nigerian Journal of Botany.vol.13.70-80
Pandey, B.P. (2000): Economic Botany. New Delhi.S.Chand and company edition.6pp.263
Schipper, R.R. (1996): African indigenous vegetables Chaltham.UK.Natural Resource Institute. Technical Report.pp.176-189
Willis, J.C. (1985): A dictionary of the Flowering Plants and Ferns. Cambridge. University Press.pp.1245