Normal and teratological pistillate spikes of Typha angustifolia (Typhaceae): gross aspects of morphology, anatomy, symmetry, and inflorescence dehiscence

Abstract

Normal and teratological pistillate spikes of Typha angustifolia were found at the same locality in Ohio, U.S.A., and the individual spikes exhibited radial, dorsiventral, and mirror-image symmetry, as well as polarity. Dorsiventral symmetry provided a frame of reference for comparing normal and teratological individuals. Both kinds of pistillate spikes were interpreted to have dorsal and ventral surfaces, sagittal and frontal planes, right and left sides, length, width, and height. Present in teratological spikes, but absent from normal ones, were either split(s) within the central stem axis or exceptionally long type-1 furrow(s). Split(s) or type-1 furrow(s) divided a teratological spike longitudinally into two to five subunits. Where two subunits were present, division was solely along the sagittal plane, whereas spikes with three to five subunits were divided along the sagittal plane and along, or parallel to, the frontal plane. In the case of teratological spikes with two to four subunits it was possible to number and compare subunits in a consistent manner. On some teratological spikes after splitting, subunits had become bowed, rotated, and curled or folded. Apparently, in teratological spikes, indentations and type-1 and type-2 furrows along the sagittal plane function, collectively, as a line of dehiscence. Key words: Typha, morphology, anatomy, symmetry, inflorescence, dehiscence.