The palynology of the malvaceae of Texas

A monographic study of the pollen morphology of 78 species of 19 genera of Malvaceae in Texas was done. Keys to these genera and their species were prepared. The study included the determination of sizes and shapes of the pollen and the characteristics of excrescences, apertures and the exine. Primarily, the pollen were acetolyzed, bleached and mounted on slides in glycerine jelly and in silicone oil. A few slides were also prepared by the methods of Wodehouse and Trought. For measurements one or more slides of acetolyzed pollen were used for each species. The data obtained for the pollen mounted in silicone oil were converted and made comparable with those of the pollen mounted in glycerine jelly. Ten to 25 pollen were used from each slide of a species for the measurement of sizes and the determination of their shapes. Of these, 10 pollen grains were selected for the measurements of the rest of the structures. The pollen grains of Malvaceae studied were suboblate to prevailingly spheroidal in shape, medium to very large, aperturate and ispinulate to mostly spinate. The genera of the tribes Ureneae, Hibisceae, the subtribe Malvinae, genera Malvastrum and Pseudabutilon of the subtribe Abutilinae had spheroidal (occasionally spherical) pollen grains. Of the remaining, Herissantia, Bastardia and Gaya had suboblate, Hodiola had oblate spheroidal while Abutilon, Sphaeralcea, Wissadula, Anoda and Sida had both suboblate and oblate spheroidal pollen grains. The pollen were largest in the tribe Ureneae; somewhat smaller in the tribe Hibisceae (except Kosteletzkya) and smallest in the tribe Malveae. The minimum and maximum average sizes, 37.03 μ and 184.6 μ were recorded in Sphaeralcea incana and Paycnia lasiopetala respectively.