Development of Ovules in the Ovary of Japanese Chestnut (Castanea crenata Sieb. et Zucc.)

Abstract

Changes with growth in the external and internal anatomy of ovary and fruit were investigated during the period from the appearance of stigmas of female flower to the harvest of fruit in Japanese chestnut.
1. When stigmas began to appear out of the central ovary of female flower covered with scales, no ovules had been formed and only locules and placentas were found in the ovary.
2. When prickles began to appear among scales and the upright styles began to spread out, meristematic tissues were observed on individual placentas, and a week later they developed into almost complete ovules composed of outer and inner integuments, nucellus and funiculus.
3. The number of locules per central ovary was 8 to 9 in‘Tanzawa’, ‘Yamato-Wase’and‘Tsukuba’, while about 10 in‘Ibuki’. The lateral ovary had one more locules than the central one regard less of cultivars. Further, each locule always had 2 ovules.
4. Late in July, when prickles developed markedly and the stigmas began to turn brown, browning occurred also in nucelli.
5. Early in August, browning occurred in nucelli of almost all ovules and in mid-August only one ovule was recognized to be growing in each ovary. Late in August, it grew rapidly downwards filling the vacant space of the locule. The other ovules died and were pressed against the ovary wall.