ABSTRACT
Tetrasporangial anthers are characteristic of most flowering plants. In some species, however, the number of microsporangia per anther may be lower, namely one (Diapensiaceae), two (Moringaceae, Marantaceae and some members of Monimiaceae), and three (Daphniphyllaceae, along with four), or higher, i.e., eight (Zannichelliaceae, Cymodoceaceae, along with four) and even as many as fifty (Mimosaceae). Variation in microsporangium number may be due to various factors: reduction in part of the anther or its transformation into a sterile appendage (Cannaceae, Marantaceae), fusion of a pair of microsporangia at an early stage of anther development-a sporadic occurrence (Daphniphyllaceae, Nitrariaceae), stamen splitting (Adoxaceae), or anther primordium fusion at early stages, it may also be due to formation of additional septa within a microsporangium. In some families (Myristicaceae, Aristolochiaceae), the anthers unite to form synandria carrying numerous microsporangia.
