Abstract
The vascular system in the main stem and peduncles of the female flower of cucumber was investigated.
The vascular system of the main stem showed both right- and left-handedness. At each internode, nine vascular bundles were observed, arranged in double concentric circles with 5 outside (cortical bundles) and 4 inside (medullary bundles). The bundles were not connected in the internodes, but were connected at each node by an annular vascular bundle‘0’.
Most of the vascular bundles of the petiole connected with those of the internode just below the node of the petiole. Many were also connected with the next internode down, but few were connected with those of the internode just above.
Vascular bundles of tendril, lateral shoot and first and 2nd female flower on a given node fused together at their base and were connected with the vascular bundle‘0’in the node.
From these observations, it is suggested that photosynthates from the leaf might be translocated first in a basipetal rather than acropetal direction, especially to the first and second internodes below the node of the attached leaf, before being distributed to various parts of the plant.
In the peduncle of the female flower, 5 vascular bundles were observed at the proximal end and 10 at the distal end. Five types and 48 subtypes of division could be distinguished. The pattern of division also showed asymmetry as well as right- and left-handedness. Among the 5 types of division, 83.2% were type II, i.e. peduncles with 1 undivided vascular bundle +3 bundles each divided into 2+1 bundle divided into 3. Out of the total number of peduncles examined, 15.8% were type II peduncles with 1 undivided bundle at the stem side and 1 bundle opposite the stem side divided into 3, according to the illustration in the previous paper(5).
From these results, it is suggested that the direction of curvature of ovaries is associated with the asymmetry in the division of vascular bundles of the peduncle and also with the vascular arrangement in the main stem.
