** Present Address-IIMT Group of Colleges, ‘O ’Pocket, Ganga Nagar, Meerut
*The work was carried out in the Botany Department of D.N. College, Meerut
The nodal structure ranges from trilacunar to 12-lacunar. The number of traces usually corresponds to the number of lacunae. Wherever the number of traces is more than the number of lacunae, the increase in the number of traces is always adjacent to the median. Such traces are given out from the main vascular cylinder without leaving a gap. Variation in nodal organization has been observed even within the same species. The vascular cylinder may have sclerenchymatous sheath on the outer and/or inner side of the ring or each bundle may be completely surrounded by the sheath. It may be altogether absent in a few cases. The climbing species generally have a tri-or pentalacunar node whereas the robust herbs and shrubs show multilacunar condition. The trilacunar 3-trace node has been regarded as the simplest. With the advent of specialization, amplification in the number of lacunae and traces seems to have given rise to multilacunar and multitrace condition.
The nodal organization of various families has been a subject of interest since long and various phylogenetic conclusions are attached to its organization. Sinnott (1914) regarded trilacunar condition in Polygonaceae as primitive and other organizations being derived from it. Mazumdar (1955) studied the node of Polygonum and correlated it with the organization of leaf base. The present authors (Agrwal and Saxena, 1975) also described the organization of node in some taxa of the family. The present communication deals with the study of nodal organization of some 23 taxa of the family.
lacunae, trace
