Karyological Studies on Pteridaceae I

Karyotypes of Three Species in Pteris

Abstract

Karyological studies were made on three species of Pteris: P. wallichiana, P. inaequalis var. aequata and P. semipinnata. The somatic chromosome numbers of the first two species were found to be 2n=58, and the third was 2n=116.
The somatic chromosome complements of these three species can be morphologically divided into six types (A-F), of which the four types (C-F) can be furthermore divided into two groups. Namely, the chromosomes of these three species can be divided into ten groups and each group consists of six chromosomes except for A type consisting of four chromosomes. From these observations, the primary basic chromosome number can be considered to be b=10, which was found for the first time in the Pteridophyta.
The two species which possess chromosomes 2n=58 may originate from hexaploid. That is, these can be considered to be derived from the ancestral hexaploid species (2n=60) eliminating one pair of A type chromosomes. P. semipinnata (2n=116) originates from duplicating the 58 chromosomes, so this species is a dodecaploid.