Showing papers on "Dryopteris published in 1981"
Journal Article•
TL;DR: The cytology and distribution of Gymrtocarpium robertianum (Hoffm.) Newman and G. parvulum Sarvela in North America are presented, together with the distinguishing features of these two species.
Abstract: The cytology and distribution of Gymrtocarpium robertianum (Hoffm.) Newman and G. jessoense (Koidz.) Koidz. subsp. parvulum Sarvela in North America are presented, together with the distinguishing features of these two species. Gymnocarpium robertianum is confirmed as a tetraploid species with 77=80 and the newly recognized G. jessoense subsp. parvulum also has n=80. In a previous paper (Sarvela, 1978) the senior author pointed out that of the six species of the genus Gymnocarpium in the world, two have a wide circumboreal range, G. dryopteris (L.) Newman and G. jessoense (Koidz.) Koidz., while the third species G. robertianum (Hoffm.) Newman, has a smaller distribution area. The genus Gymnocarpium in North America was last treated by Wagner (1966). He considered there were two basic species over most of the circumboreal range to which he applied the names G. dryopteris and G. robertianum. In addition, he introduced "the apparent cross of G. dryopteris and G. robertianum" as a new species of hybrid origin with the name G. heterosporum W.H. Wagner. G. dryopteris subsp. dryopteris has been known as a tetraploid since the work of Manton (1950) and eastern Canadian material was examined by Britton in 1953 (n = ca. 80). The larger, tripinnate taxon of the Pacific Northwest, G. dryopteris subsp. disjunctum (Rupr.) Sarvela, is a diploid (n — 40) (Wagner 1966). This has been sufficient reason for some workers to recognize the diploid entity as a separate species—G. disjunctum (Rupr.) Ching— although the relationship between the diploid and the tetraploid is obscure. New investigations (Sarvela, 1980) have indicated that the Gymnocarpium robertianum complex may include as many as four taxa, i.e. two species, G. robertianum and G. jessoense, and two hybrids, G. heterosporum W.H. Wagner (G. dryopteris X roberti anum) and G. X intermedium Sarvela (G. dryopteris X jessoense). Our studies indicate that G. X intermedium is a common hybrid of wide occurrence. So much so that, when this taxon is identified by its aborted spores and reduced glandularity, many sheets and localities of G. jessoense subsp. parvulum Sarvela are eliminated from consideration. The other hybrid, G. heterosporum, is con sidered to be rare indeed.
21 citations
TL;DR: The archegonial mucilage ofAthyrium filix-femina and A. distentifolium paralyses spermatozoids ofDryopteris Filix-mas before they penetrate the archegonia venter of A. inaequalis.
Abstract: The archegonial mucilage ofAthyrium filix-femina andA. distentifolium paralyses spermatozoids ofDryopteris filix-mas (and in one caseD. inaequalis) before they penetrate the archegonial venter. The archegonial mucilage ofDryopteris filix-mas has a weak positive chemotactic influence on the spermatozoids of the twoAthyrium species. The spermatozoids ofDryopteris were never observed in the archegonia ofAthyrium. Incompatibility was not observed within and between the twoAthyrium species, withinDryopteris filix-mas or betweenAthyrium filix-femina and twoAsplenium species.
17 citations
TL;DR: It has been inferred from the present investigation that cytological changes like hybridity, polyploidsy and aneuploidy have played an important role in the evolution of the Aspidiaceous ferns in South India.
Abstract: Cytological investigation on 46 taxa belonging to 43 species under 14 genera of South Indian Aspidiaceae has been carried out. Chromosomal variations such as hybridity, aneuploidy, polyploidy and supernumerary division following meiosis have been encountered, The occurrence of species complexes has been detected in Arachnoides aristata and Cyclosorus interruptus. Bolbitis quoyana, Diplazium silvaticum, Tectaria paleocnemoides and T. decurrens var. minor have been found to be natural hybrids and the possible origin of the former three species has been suggested. Fifty per cent of the total 46 taxa investigated was found to be polyploids. Aneuploid changes in chromosome number have been detected in Thelypteris and Dryopteris. The origin of the different basic numbers in the genus Thelypteris has been discussed. It has been inferred from the present investigation that cytological changes like hybridity, polyploidy and aneuploidy have played an important role in the evolution of the Aspidiaceous ferns in South India.
10 citations