Cytotaxonomic Studies on Mosses from Washington and Idaho

Abstract

Meiotic chromosome counts were made of 22 Washington and Idaho mosses in 14 genera and eight families. The chromosome numbers for 20 taxa are reported for the first time and two other taxa have been found to have a chromosome number different from that previously reported. This report is a continuation of a cytotaxonomic study undertaken in the course of assisting Dr. Elva Lawton in the preparation of a moss flora of the Pacific Northwest. The meiotic chromosomes of the spore mother cells were studied with the cytological techniques described in an earlier report (Ireland 1963). Acetic-orcein was used exclusively in the present study since it was found to be the most effective in producing the greatest contrast between the chromosomes and the cytoplasm. The collections cited in this paper are represented by voucher specimens in the University of Washington herbarium. The counties cited are in Washington unless stated otherwise. DITRICHUM MONTANUM Leib., n=13 (Fig. 1). Skamania Co., July 12, 1964. RRI-8833. The number n=13 for this autoicous species agrees with some of the other reports for the autoicous members of Ditrichum subgenus Ditrichum. The meiotic chromosomes are similar in staining qualities and behavior to those described for D. pallidum (Hedw.) Hampe (Al-Aish & Anderson 1961). Morphologically, however, the chromosome complement differs from it and from the other autoicous species studied thus far by having one bivalent noticeably larger than the other 12 (Fig. 1). A large and conspicuous bivalent is also found in the complement of other members of the family Ditrichaceae, specifically D. cylindricum (Hedw.) Grout (as Trichodon cylindricus (Hedw.) Schimp., Steere 1954) and Ceratodon purpureus (Hedw.) Brid. (Steere, Anderson, & Bryan 1954). Ditrichum montanum was considered to be a rare moss in the western United States for many years. Anderson and Bryan (1958a), in a cytotaxonomic revision of the autoicous species of Ditrichum subgenus Ditrichum, were unable to obtain cytological material of this species. Furthermore, they were able to locate only four herbarium specimens, collected in Washington and Idaho, which they 1 This study was supported by grant G-19332 from the National Science Foundation to the University of Washington. I am especially grateful to Dr. Elva Lawton and Dr. A. R. Kruckeberg of the University of Washington for their help. I wish to thank Dr. and Mrs. N. Higinbotham of Washington State University for collecting some of the cytological material. 2 Department of Botany, University of Washington, Seattle, Washington 98105. This content downloaded from 207.46.13.111 on Tue, 09 Aug 2016 04:50:03 UTC All use subject to http://about.jstor.org/terms 1965] IRELAND: CYTOTAXONOMY OF MOSSES 73