Variability of stem morphology in lycopodium clavatum (Lycopodiaceae) is not related to ploidy level

Abstract

Background and aims – Based on pedicel length, three morphological forms of Lycopodium clavatum L. are recognized. It has been previously reported that these are correlated with the ploidy level. The present investigation compares for the first time in Poland the diversity in pedicel length with the corresponding nuclear DNA amount and the ploidy level of L. clavatum. We aimed to find correlation between the morphotypes and the ploidy level in the Polish population of L. clavatum. Methods – Samples of shoots were taken from two clumps of L. clavatum. The ploidy level and 2C DNA content analysis was combined with pedicel length measurements. The ploidy level and genome size estimation were performed using flow cytometry. Key results – We found the occurrence of two morphological types of generative stems. The morphotype A produced distinct long pedicels (10.8–43.3 mm). The morphotype B had visible, but very short pedicels (4.5–9.3 mm). We tested the already existing hypothesis, according to which the A and B morphotypes represent respectively diploid and triploid ploidy level. Surprisingly, we did not find such a correlation. Regardless of the morphotype, all the studied plants were diploid, with 5.04–5.13 pg/2C nuclear DNA content. Conclusions – The occurrence of stems of different morphology in L. clavatum was not linked to the ploidy level. It is not excluded that the morphotypes may be genetically determined, but in the studied material, the ploidy level is certainly not at the origin of their differentiation.