A REVIEW IN NODAL ANATOMY FOR PLANTS
Nodal anatomy reveals the number, behavior and fait of bundles in each node and internode. Firstly, three main types of nodes represented by the one trace- one gap, the three trace- three-gaps, and the multi-traces- multi gaps in plants were proposed. Then the fourth types of nodes, represented by two- multi traces - one gap , was added to nodal types, while the fifth type (split –lateral) has been proposed, where a single trace associated with numerous leaves by splitting as found in different families from Angiosperms.Branches traces are distinct from leaf ones, and it represented of one or several bundles formed in axillary of leaves, commonly branch trace and middle leaf trace formed with the same gab,One of the important facts of studying nodal anatomy is the relationship between nodal structure and leaf base referring to stipules and sheathing base as well as the phyllotaxy. In monocot plants leaves characterized by sheathing bases, So the leaves nodes appeared with numerous leaf traces separated from different stem bundles, in Dicots plant different nodal types recognized.the studies of nodal anatomy are considered as an important features in taxonomical studies and phylogenetic studies on Dicots plant, most the studies revealed the di-traces and tri-traces nodes considered as primitive type while the uni-trace or multi-traces node are the advanced and it was proposed either by reduction or amplification.
Keywords: Nodal Anatomy, Gap, Trace, Angiosperm, Gymnosperm