Systematics seeks to sort out differences in species which though of common ancestry, have over time developed characteristics that marks them out into differing taxons. a cardinal point of note in systematics is to ascertain that perceived differences in species are genetically oriented and so enduring, as against plastic characters that are mere responses to to various biotic and abiotic environmental factors.Thus, systematics is a living science and it's progress may not merely be in the discovery of new species, but in ensuring that every species in a taxon is rightly deserving of that position. To ascertain the position of true speciation, attempts must continually be made to study species under various environmental conditions to discover the true identities of exhibited characters-whether they are plastic or genetically oriented. Plastic responses will only lead to "paper species". In this study, stomatal size, density, epidermal size, density and the characters of anticlinal wall sinuosity of Amaranthus spinosus Linn., growing under various environmental conditions were observed and analyzed.