メロン, キュウリ, トカドヘチマの果実における維管束と心皮の配列

Abstract

The main vascular connection observed in the fruits of melon, cucumber and Luffa acutangula Roxb. were as follows; peduncle-receptacle-pericarp (exocarp-mesocarp-endocarp)-septum-fruit axis-placenta-seed (ovule). Some vascular bundles were also observed to reach the fruit axis directly from the peduncle, although they were smaller in number and diameter than those running through the receptacle.The basic number of vascular bundles in each part was 10 each in the peduncle, receptacle and exocarp, 1 per carpel in the fruit axis and 1 per ovule in the placenta. Many vascular bundles were observed in the mesocarp and endocarp, but their basic number could not be determined.The direction of vascular bundles in each part was as follows; acropetal in the peduncle, fruit axis, receptacle, exocarp and endocarp, tangential in the mesocarp, centripetal in the septum, and centrifugal in the placenta.There were usually 5 carpels in ‘Wasada-uri’ melon although the number sometimes decreased to 4 or 3 at high night temperatures. In ovaries consisting of 5 carpels, each carpet corresponded to 2 of vascular bundles of receptacles, but in ovaries consisting of 3, 4 or 6 carpels there was no such clear correspondence.In ‘Wasada-uri’ ovaries consisting of 3, 4 and 5 carpels, 4, 8 and 5 types of carpel arrangement, respectively, were observed in relation to petals and calyxes. Among these, the typical ones were III1, IV1 and IV3 and V2 and V4 (refer to Table 2-4).Assuming that the number of carpels increased from 1 to 5 in ontogenetic differentiation as leaves or floral leaves, its sequence and arrangement seemed to be I, II1, III1, IV1 and IV3, V2 and V4 (refer to Fig. 12).From these results, it was suggested that the carpels differ congenitally in time and hence in relative position in their ontogenetic development, which consequently results in differential growth of respective carpels and respective sides of ovary and fruit.