Seed morphology in the genus Pinguicula (Lentibulariaceae) and its relation to taxonomy and phylogeny
Degtjareva, Galina; Casper, Jost; Hellwig, Frank; Sokoloff, Dmitry
published: Sep 7, 2004
Seed morphology, anatomy and spermoderm ultrasculpture are studied using SEM and light microscopy in 19 of about 80 species of the genus Pinguicula (Lentibulariaceae). All subgenera recognised by CASPER are covered by the study. Seeds of Pinguicula are small and have ellipsoidal or spindly form. Seeds of all examined species are characterised by the same groundplan. On the other hand, we found differences in some characters between studied samples. Some characters of seed coat structure are probably significant at the sectional level. Some other characters are probably significant on specific or infraspecific level. The data on seed coat structure generally confirms that section Pinguicula represents a natural taxon. Embryo structure of Pinguicula is of special interest due to variation in the cotyledon number. We found two cotyledons in P. crystallina, P. lusitanica, P. moranensis, P. variegata, and P. villosa, which represent all three subgenera. The rest of the examined species possess a single cotyledon. We suggest that cotyledon number was quite unstable in the evolution of Pinguicula. Some features of seed coat morphology are much more congruent to flower morphology than embryo structure. This is in contrast to many other families of Lamiales, where an embryo with two cotyledons is a very conservative character. However, it is difficult to demonstrate that cotyledons of Pinguicula are homologous to cotyledons of other dicots.