| Summary: | 碩士 === 中興大學 === 生命科學系所 === 95 === Mitrastemon (Rafflesiaceae) are nonphotosynthetic parasites that live on host roots. Two species of Mitrastemon, M. kanehirai Y. Yamamoto and M. kawasasakii Hayata are distributed mainly in broad-leafed forests at mid-altitudes of Taiwan. The flower is bisexual, hypogynous, and with protandrous, tubular androecium whose anther are fused in a broad ring. The growth period of Mitrastemon can be divided into four stages: bud, anthesis (androecium and gynoecium), fruit, and seed. From anthesis to fruit stage, we observed a large mount of nectar stored in upper scare leaves. We choice different growth stage of Mitrastemon to observe necatry under SEM. Some nectary pores were located at the base overy, perianth, and upper scale leaves, respectively. The size of the nectary pores did not change significantly in four growth stage. There were many nectary pores on the ovary, and the pores extended into round at the gynoecium stage. Sizes of the necatry pores were rather difference (30-160μm in diameter), round to ellipse, and were randomly distributed. Nectary pores were open at all stages. Compared with other plants, Mitrastemon offers more volume of nectar, but the concentration of the nectar was lower. The volume and concentration of Mitrastemon nectar was lower at the beginning of androecium stage, and higher at gynoecium stage, and slowly down in fruit stage. M. kawasasakii Hayata had more volume of nectar and long blooming time than M. kanehirai Y. Yamamoto, but with slightly lower concentration of nectar. The sugar composition of Mitrastemon nectar were mainly fructose and glucose, and sucrose was only of small amount.
|
|---|
