Timing of Reproductive Organs Maturity in Proterandrous Malva sylvestris L.

Abstract

Flower development of protandrous species Malva sylvestris L. was divided into 12 stages, as revealed by applying histological and scanning electron microscope techniques. Flower development started with the conversion of apical meristem into floral meristem. Initiation of male organ primordia started before that of female organ. Five rounded structures called corolla/androecium units differentiated from floral meristem, on which stamen primordia emerged. When pollen mother cells exist in the pollen sacs, initiation of carpels starts from floral meristem. Concurrent with the termination of meiosis in pollen mother cells, ten loculed ovary comed in view. Simultaneously with the occurrence of vacuoleted pollen grains, megaspore mother cell becomes visible in the nucellar tissue. Concominant with the existence of two celled-pollen grains, the style was formed and ovule becomes anatropous. When pollen grains are shed in male phase, ten branched stigma appeared on the upper part of the style, but receptive surface was not fully formed to accept pollen grains. Female phase is characterized by the opening of stigmatic branches with papillate receptive surface. Timing of reproductive organs maturity overlapped for a while, thus, the reproductive stragey of M. sylvestris was incomplete proterandry.