Chromosome Numbers in Cheilanthes, Notholaena, Llavea and Polypodium

Abstract

The chromosome numbers of 10 previously uncounted species in Cheilanthes and 1 species of Notholaena are reported. Several confirmatory counts are also listed. One of the plants, Cheilanthes parryi, should probably be retained in the genus Notholaena. Four plants are sexual diploids, three are diploid apomicts, four are triploid apomicts, and three are tetraploids.

Chromosome studies of cheilanthoid ferns (Pteridaceae: Cheilanthoideae) from the western United States and Mexico

“…Our counts of n ϭ 29 and n ϭ 58 for C. horridula appear to support Reeves' classification of this taxon, given that the C. microphylla group is the only assemblage of New World Cheilanthes species with a consistent base number of x ϭ 29. The current study also confirmed previous reports based on x ϭ 29 for C. alabamensis (Knobloch, 1967;Knobloch et al, 1975) and C. aemula (Knobloch et al, 1975).…”

“…8), not 2n ϭ 116 as hypothesized by previous authors. A similar situation was encountered in C. villosa, for which Knobloch (1967) reported a count of 2n ϭ 87. Collections from two populations of C. villosa from southern Arizona indicate that the chromosome number of this species is n ϭ 90 ( Fig.…”

“…There are conflicting reports for C. feei, the only other member of the C. fraseri group included in this study. Although Knobloch (1967) reported a chromosome number of 2n ϭ 87 for this species, collections from two separate populations in Arizona clearly show n ϭ 2n ϭ 90 (Fig. 4).…”

“…Cheilanthes tomentosa has been counted repeatedly, and the majority of published reports indicate that this species is an apogamous triploid with n ϭ 2n ϭ 90 (Knobloch, 1966(Knobloch, , 1967Whittier, 1970;Knobloch et al, 1975). The conflict in this case involves counts of 2n ϭ 87 and n ϭ c. 89 published by Wagner et al (1970) and Lloyd (1966), respectively.…”

“…There is one conflicting report concerning the chromosome number of C. aemula, which was given as n ϭ 30 by Knobloch (1967). However, there is good reason to doubt the validity of this count because the report of 2n ϭ 58 by Knobloch et al (1975) is derived from the same collection.…”