側枝及び不定根と母軸との維管束連絡トウモロコシの維管束解剖第6報

抄録

The procambial strands, initiated at the base of the axillary bud, elongate basipetally and are connected with those of the mother axis. A few branch traces follow the horizontal courses at the node, or become blended with the nodal plexus, and thus their further accurate behaviours are difficult to trace. The nodal plexus is of the secondary origin in the histogenesis, and if those branch traces are left out of consideration, most of the trace strands from the axillary bud are connected, as a rule, with the vertical bundles of the mother axis at the node; i.e. the outermost peripheral (outer) and compound (inner) bundles of the axillary bud are connected respectively with outer and inner axial bundles situated at the side facing the axillary bud. A few branch traces pass through the node downwards without being connected with any bundle of the mother axis. In the case of the developed axillary shoot, some branch traces seem to pass across the centre of the mother axis and join directly with the axial peripheral bundles, situated at the side opposite to the axillary shoot. As such a behaviour of branch traces is not confirmed in the early stage of the bud, it is interpreted as a secondary modification caused by the predominant development of one of the nodal horizontal strands which are initiated between some branch traces and vertical axial bundles. The pattern of the vascular connection of the axillary shoot with its mother axis will be discussed in the following paper of this series.
Before the intercalary elongation of the shoot takes place, an arc of meristematic tissue becomes initiated closely attaching to the outermost peripheral procambial strands of the stem, and later it develops into a dome-shape. From the summit of the dome the adventitious root apex is initiated, and then some horizontal procambial strands are differentiated between several points of the dome base and its adjacent compound procambial strands of the stem; thus the vascular connection of the stem with adventitious root is established. The horizontal strands above mentioned usually elongate more deeply towards the centre of the stem, but they are not connected there with any of vertical axial bundles.