The Systematic Relationships Of Sparganiaceae And Typhaceae

Micromorphology and floral development of Sparganiaceae, Typhaceae and related families were examined by scanning electron microscopy (SEM). Results are as follows:1. There are some differences in leaf epidermis among Sparganiaceae, Typhaceae and related families, including the type of stomata apparatus, attachments of stomata apparatus and the pattern of anticlinal walls. Their pollen grains also are different, such as the pollen morphology, the size of the long axis, the type of aperture, and the sculpture of the pollen exine, and so on. These characteristics are significance in taxnomy, which play important roles both in taxonomic research and in discussion of systematic relationships.2. Sparganium fallax is characterized by the presence of unisexual flowers on the same inflorescence axis. The 3-5 pieces of perianth primordia of male flower arise almost simultaneously. The lately-initiated 2-5 stamen primordia also arise nearly simultaneously. The 4-5 pieces of perianth primordia arise in a whorl from the female floral primordia. The floral development of Typha is the same as Sparganium. The distinction between them is that perianth of Typha are in slight and filiform appearance. There are six tepals in Acorus tatarininowii Schott, an abaxially median tepal that is initiated first, and much larger than the other tepals. The development of two adaxial tepals are initiated one after another. The way of the second tepal whorl is similar to the first one, and unidirectional flower development with an inversion of organ initiation. There are six stamens, initiating two whorls, and then were arranged in one whorl at subsequent stages of development. The three carpels are united for most of their length but are free in a very short apical zone. By studing the floral development of three species, we not only recognized the early stages of floral development, but also knew the complexities and varities of floral structures. These studies provided important evidences for discussing the systematic position of Sparganium.3. The floral development of Typha is the same as Sparganium. Therefore, we believe that Sparganium and Typha are closely related, and suggest that Sparganium should be placed in Typhaceae s. 1.. The hairs covering the ovary in the female flowers of Typha and the perianth in flower of Sparganium fallax were homologous characters, but Typha is more evolved than Sparganium.4. Comparison of the floral development of Acorus with Typhaceae s. 1. indicated that their relationships are remote. There are some primitive characteristics in Acorus, so wethought that the systematic position of Acorus is moreprimitive.