Seedling Morphology of Four Acacia Mill. (Fabaceae) Species and Its Significance in Plant Taxonomy

Acacia species commonly identify by their reproductive characters such as indefinite number of stamens (more than 10) that are free or united only at the base and a calyx that is in valvate aestivation, pods, etc. In India Acacia species are found in all climatic regions but they are found to play a major role in arid and semi-arid areas and effect the environment and communities. The seedling is the very juvenile stage of a plant after germination. Seedling investigation give a good data for identify a particular species at juvenile stage or germination phase. In seedling taxonomy we do focus on wide range of characters such as root, hypocotyl, cotyledon, epicotyl, stem, phyllotaxy, eophyll, heteroblastic development of leaves etc. In Acacia seedlings, the number of leaflets, spines, and the shoot height are also important characters. Seedling taxonomy as a tool gives a very significant knowledge about the process of establishment of stable adult traits in mature plants from transition to juvenile stage. Acacia species seeds covered by thick seed coat that inhibit the germination of seeds so to reduce the dormancy period various pre-germination treatment methods are used such as soaking in boiling water, mechanical and chemical scarification of the seed coat. After germination we observe seedling characters and make a dichotomous identification key to distinguish them. As mature Acacia are usually identify and distinguished from other plants by inflorescence and pod's characteristics. So there is a need for their distinction at earlier stages where these reproductive characteristics are absent.