Stem anatomy and its relevance for the taxonomic survey of Selaginella subg. Gymnogynum (Selaginellaceae)

Autor: Layse Kristine Corrêa Lopes, Ana Carla Feio, Luiz A. A. Góes-Neto
Rok vydání: 2020
Předmět:
Zdroj: Plant Systematics and Evolution. 306
ISSN: 2199-6881
0378-2697
DOI: 10.1007/s00606-020-01655-x
Popis: The current circumscription of Selaginella subg. Gymnogynum fails to accurately define and describe the stem articulations and stem vascular system of its representatives. A structural revision may improve species delimitation within subgenus Gymnogynum and is thus pivotal for taxonomic and evolutionary studies in Selaginella. We analyzed 34 specimens from 12 species of S. subg. Gymnogynum, two species of S. subg. Exaltatae and one species of S. subg. Stachygynandrum, which we obtained from herbaria. Samples were subjected to the herborization reversal procedure and processed following usual methods in light microscopy. All sampled Gymnogynum species as well as S. exaltata are articulated. Only S. anaclasta (subg. Exaltatae) and S. coarctata (subg. Stachygynandrum) lack articulations. The articulation region can be characterized and classified based on the occurrence of swellings or nodules (hyperplasia), the predominant presence of pectin in the cell wall and formation of grooves that reach the cortical region (constrictions). These three traits combined form five articulation types. We found the following types of stem vascular system: haplostele, actinostele, plectostele and actino-plectostele. In Gymnogynum, we found the bistelic haplostele, plectostele and two variations of actinostele. Our analysis allowed for a standardized and revised characterization of species in subg. Gymnogynum, with additional information on subgenera Exaltatae and Stachygynandrum, thereby expanding the database of anatomical traits that may contribute not only to achieving a more accurate taxon delimitation but also to subsidizing further studies on the evolutionary history of Selaginella.
Databáze: OpenAIRE
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