Foliar epidermal study of some species of Aglaonema Schott (Araceae) in Nigeria
The adaxial and abaxial epidermal surfaces of six species of Aglaonema Schott were studied in order to document characters of taxonomic importance among them. The species are Aglaonema brevispathum Schott (Engl.) Engl., Aglaonema commutatum Schott, Aglaonema costatum Schott, Aglaonema crispum Schott, Aglaonema pictum Schott and Aglaonema rotundum Schott. Epidermal peels of both the adaxial and abaxial surfaces of the species were made following standard procedures. Qualitative and quantitative characters were observed and measured respectively. Photomicrographs of the surfaces were also taken. Generic characters revealed include brachyparacytic stomata complex, elliptic stomata shape, polygonal to irregular epidermal cell shape as well as straight to wavy anticlinal cell wall pattern on the abaxial surface. Additional anisocytic and anomocytic stomata complexes were present in some of the species. The hypostomatic nature of A. rotundum was documented. This clearly separated it from the other species in this study which are amphistomatic in nature. Anticlinal wall pattern varies from wavy to undulating to sinuous on the adaxial surface and straight to wavy on the abaxial surface of the species. Irregular epidermal cell shape on the adaxial surface separated A. costatum and A. pictum from the other species which have polygonal to irregular epidermal cell shape. Highest epidermal cell size and stomata size was encountered on both surfaces of A. pictum. Druses and raphides of calcium oxalate were present in A. commutatum, A. costatum and A. crispum which delimited them from the other species. The study reveals key diagnostic features among the species studied. Further research work from other fields of evidence is recommended in order to shed more light on the taxonomy of the species.
Key words: Araceae, Aglaonema, Taxonomy, Epidermis, Brachyparacytic