On the polarity and tetrad arrangements in some mono- and diaperturate angiosperm pollen grains

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Abstract
The mono- and diaperturate pollen grains have been found to be widely different in the orientation of apertures with regard to their polarity. The nature, position and polarity of eleven apertural types from widely unrelated taxa of angiosperms, have been studied in tetrad as well as in monad states, e.g. monosulcate (both ana- and catasulcate), extended-sulcate, sulculate, meridiono-sulculate, monoulcerate, disulcate, diulcerate, disulculate, diporate and dicolpate conditions. Illustrations have been provided to demonstrate the respective positions in tetrad conditions and equatorial and polar views in the monad condition. Avolutionary sequence transpires from these apertural types, from simple to more complex, which have been shown in a phylogenetic tree