Merced-Alejandro, Amelia

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Heterochronic sequence for the development of paraphyses in Neckeropsis Schimp. (Bryophyta: Neckeraceae)
(2004) Merced-Alejandro, Amelia; Sastre-De Jesús, Inés; College of Arts and Sciences - Sciences; Kolterman, Duane A.; Pérez Muñoz, Carlos A.; Department of Biology; Almodóvar, José
Neckeropsis is a genus of tropical distribution with two species in Puerto Rico, N. disticha and N. undulata, that present leaf-like structures, the ramenta, that grow on the perichaetia after the fertilization of the archegonia. These structures have been identified as ligulate perichaetial leaves or multiseriate paraphyses, but their origins and homology are not clear. A morphological and ontogenetic description was made for N. disticha using stereoscope, light microscope, and paraffin and plastic resin infiltration procedures. Transitions between uniseriate and multiseriate paraphyses were documented at different times in the development of the fertilized branch. Nine other species were examined to evaluate the presence and modifications of the ramenta; five species possess the multiseriate paraphyses in different developmental stages. During the development of the fertilized archegonia, the branch presents the transitional stages of the development of paraphyses as a heterochronic sequence similar to the heteroblastic sequence in branch leaves.