Morphological Characters, Occurrence and Distribution among Members of the Family Solanaceae in Parts of the Niger Delta Ecological Zone

: This study investigated a comparative micro-morphological features of 14 species in the family Solanaceae, using trichome and stomatal complements in delimitation of species and genera within the taxon, family. The genus Solanum L. is the largest among the genera in Solanaceae. Solanum aethiopicum Linn. Solanum macrocarpon Linn. Solanum torvum Swartz. Solanum anomalum Thonn. Solanum erianthum D. Don, are covered with stellate trichomes. While Solanum nigrum Linn., Solanum lycopersicum Linn., Solanum incanum Linn., Datura spp., Schwenckia spp., Capsicum spp., Physalis spp. have simple uniseriate trichomes. S. aethiopicum Linn. S. torvum Swartz. S. lycopersicum Linn, and Physalis micrantha Linn, revealed higher trichome indices. In most species, these trichomes are not visibly observed with the naked eyes. While in some others such as in S. torvum and S. lycopersicum the trichomes are observable on the plants. Glandular hairs are also present in Solanaceae. Stomata is amphistomatic, types commonly observed are: anisocytic and anomocytic, while paracytic and tetracytic stomata are sometimes revealed in stem epidermis in Solanaceae . The usefulness of trichome and stomatal complements in species and generic taxa are recommended as pertinent characters for classification in Solanaceae and their density may vary from one ecological zone to another. ©JASEM http://dx.doi.org/10.4314/jasem.v20i3.12


INTRODUCTION
Stomata are considered to be one of the major epidermal structures within the leaf organ that have allowed higher plants to adapt to virtually all terrestrial environments on earth, this is made possible by means of adjustment of their size, density and distribution (Zarinkamar, 2006b). An alteration of leaf stomatal density can be used as an indicator of environmental change (Case, 2004). Solanum roustrum, the shrubby nightshade, is a thorny perennial with velvet leaves and stems due to dense stellate trichomes present on all over the plant (USDA, 2015). Solanaceae is predominated mostly by anomocytic stomata. Trichome and stomatal complements are necessary diagnostic characters used in identification at species and generic levels. The type of hair can be of diagnostic value at species level, sometimes also at generic level, but rarely at family level (Cutler, 1977).The word 'uniseriate' is really an anatomical term rather than morphological and does not describe the shape. 'Multiseriate' is not unique to trichomes, it could also mean multi layers as in epidermal and hypodermal axial parenchyma (Metcalfe and Chalk, 1979).
The present study is aimed at producing a more current and comprehensive taxonomic data involving the micro-morphological characters, their occurrence and distribution among members of the family Solanaceae.

MATERIALS AND METHODS
Study Area: The areas covered were different Localities in Rivers State, Imo State and Abia State parts of the Niger Delta, Nigeria.

Sample Collection:
The materials used for this study were collected from both cultivated domestic species and wild species or raised from seeds purchased from the fruit and vegetable markets.
Sample Preparation: Fresh leaves and stems were peeled and bleached using sodium hypochlorite for about 2 minutes following the method of Cutler (1978). For other fresh leaves whose epidermal layers were difficult to peel, chemical frictions or scraping method were used, usually the surface to be examined was placed on a glass slide while the other surface was carefully cleared by flooding with 5% sodium hypochlorite and scraping with cork material 584 WAHUA, C; EDWIN-WOSU, NL or razor. The cleared epidermal layers obtained were then washed in several changes of distilled water and stained with Alcian blue or safranin and temporarily mounted in aqueous glycerol solution (Cutler, 1978). Photomicrographs were taken from good preparations. Stomatal studies were done from the cleared leaves and stems. The length and width of the stomatal complexes (guard cells) were measured using a calibrated eye piece graticule following the method of Arnold (1973). The stomata observed were viewed with the light microscope and were measured or calculated in unit area using the stomatal index  respectively. The studies further revealed the presence of anomocytic, anisocytic, tetracytic, paracytic, stomata. S. nigrum is observed with the highest stomatal index among the species studied. (Table 1). S. aethiopicum, S. torvum, S. lycopersicum and Physalis micrantha showed higher trichome indices than others. (Table 2) Arrows revealed stellate trichomes Plates 1a: S. aethiopicum Linn. Adaxial foliar epidermis with numerous stellate trichomes. 1b: S. torvum Swartz. Adaxial foliar epidermis with high density of stellate trichomes. Morphologically, most members of the genus 'Solanum' with rough lamellae possess stellate trichomes, it is envisaged that the numerous dense nature of the hairs is the reason for the leaf texture, as also supported by (USDA, 2015 White arrow showed curved hair with bulge head termed covering trichome, which signified a kind of oil secretory function which gave the leaves and stems glossary outlook. (Figure 2q). The presence of tapering trichomes was also discovered in Schwenckia, (see figure 3g).     Simple uniseriate trichome complements in Solanaceae. 3a and 3h are covering trichomes unique to Schwenckia americana along with 3g which is a tapering trichome, 3b; 3e, and 3l were observed in Datura metel. 3c, 3f, 3j, 3k, 3r and 3s were revealed in Capsicum spp., 3g, 3m and 3p showed in Solanum lycopersicum, while 3d, 3o, 3q and 3u were found present in Physalis species.    Conclusion: In Solanaceae, stomatal and trichome complements are used to classify some species to a very great extent. There are both simple uniseriate and multiseriate trichomes. Contiguous cells, glandular trichomes, anomocytic and anisocytic stomata are very common in Solanaceae. Tetracytic and paracytic stomata are also observed in Solanaceae. Stomatal and trichome complements are vital diagnostic characters among species found in genera within any given family of plants. It is obvious that comparative studies among different families of plant may prove very difficult. It is not out of place that with the present day descriptions assigned in micro-morphological studies there may arise in the near future, stomatal and trichome classification that may be acceptable to an appreciable extent.