摘要:

AbstractTwo new species ofCololejeunea(sub-genusLep tocolea),C. pandeisp. nov. andC. dentifoliasp. nov. are described from fudia. Both species are epiphyllous with ascending leaves. The former is characterized by uniseriate stylus, serrated margin of leaf, discoid gemmae on ventral surface of leaf-lobe with 2-3 mamillose cells and inflated perianthwith lateral winged plicae. The latter is characterized by dentate margin of leaf, leaf-cells with distinct trigones and intermediate nodular, thickenings, bidentate leaf-lobule and discoid gemmae with 4 mamillose cells.

ISSN:0373-6687    

DOI:10.1179/jbr.1982.12.2.227

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

AbstractTwenty-eight moss species have been investigated cytologically. Mitotic karyograms have been presented for most of these species and these show a remarkable similarity in then= 11 karyotype. Nine of the eleven chromosomes have terminal or sub-terminal centromeres. Lightly staining heterochromatic bands frequently occur along the axis of the chromosomes and very often these are the sites of chromosome bending; it has been suggested that these may be areas of neocentric activity. The karyotypes investigated show a reduction series of chromosome number which is paralleled by an increase in the number of long metacentrics; since the number of major chromosome arms is maintained in most of the species it has been suggested that Robertsonian fusion has been an important mechanism in the evolution of the Bracytheciaceae, and probably in all Diplolepidous mosses. Polyploidy has also played an important role in speciation. Finally it has been proposed thatn= 11 is the primary basic number in the Diplolepideae.

ISSN:0373-6687    

DOI:10.1179/jbr.1982.12.2.233

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

AbstractChromosome counts are reported from five species of Antarctic hepatics belonging to five genera and four families. The chromosome numbers in the generaHerzogobryum(H. teres n= 9) andPaehyglossa(P. dissitifolia n= 9) are reported for the first time. The first chromosome count fromLophozia excisa, n= 27, is the highest reported fromLophozia.A diploid number,n= 18, is reported for the first time fromBarbilophozia hateheri; a second count,n= 9, agrees with earlier reports. The commonest Antarctic liverwortCephaloziellacf.exili[lorahasn= 18 and this agrees with earlier reports for the genus.

ISSN:0373-6687    

DOI:10.1179/jbr.1982.12.2.259

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

AbstractThere are three cytotypes ofAtrichum undulatumin the British Isles withn= 7, 14 and 21. The triploid is the most frequent (56.71% of populations sampled), followed by the diploid (32.52%) with the haploid the rarest (10.77%). There is a south to north trend of a decrease in the proportion of haploid populations and an increase in triploids. The cytotypes are indistinguishable morphologically both before and after cultivation under uniform conditions and cannot be accorded taxonomic recognition.

ISSN:0373-6687    

DOI:10.1179/jbr.1982.12.2.265

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

AbstractThe spore wall morphology ofTimmiella barbuloides(Pottiales, Musci) is described. The spores are catalept, with an ornamentation pattern consisting of unevenly spaced, shortly pedunculated pilum-and gemma-like processes. The spore coat consists of three, unevenly thick layers: intine, exine, and perine. The exine is not involved in wall ornamentation, the processes consisting of perine only. The leptoma, a spore coat area involved in germination, consists of an intine markedly thickening in an area of thinning exine and, outside, with a spore coat area where perinous processes become sparse. On the basis of observations and of the data reported in recent literature the classical definition of the leptoma is modified. It is considered to be a structurally specialized, but not necessarily thin, area.

ISSN:0373-6687    

DOI:10.1179/jbr.1982.12.2.273

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

AbstractPhotosynthetic activity of attached sporophytes is very low (a few per cent or less) compared with that of associated gametophyte structures (perianth, bracts and uppermost leaves) inCephalozia bicuspidataandLophocolea heterophylla, or with even small areas of thallus inPellia epiphylla. Photosynthetic uptake of14CO2by developing sporophytes ofP. epiphylla,C. bicuspidataandL. heterophyllais at most a few per cent of the14C translocated subsequently from the gametophyte, and could be negligible. InL. heterophylla, the perianth, bracts and uppermost leaves appear to play only a limited role in nutrition of the sporophyte, the leafy shoots making a major contribution. InC. bicuspidatathe perianth and leaves of the short archegonial shoot may provide a substantial part of the nutrition of the sporophyte. There is some indication in all three species that translocation from the gametophyte is most active when the sporophyte reaches full size but is still green, declining in the final stages of maturation of the capsule.

ISSN:0373-6687    

DOI:10.1179/jbr.1982.12.2.279

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

AbstractThe length of the annual growing season of five Sphagnum species was investigated on the Silver Flowe N.N.R. It ranged from five to six months forS. papillosumandS. magellanicumthrough approximately seven and ten months forS. capillifoliumandS. auriculatumvar.inundatumto twleve months forS. cuspidatumA mechanism of hollow and pool enlargement is proposed.

ISSN:0373-6687    

DOI:10.1179/jbr.1982.12.2.287

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

AbstractAn unusually persistent ventral canal cell has been observed in a few archegonia ofPhyscomitrium cyathicarpumMitt. Ultrastructural investigations revealed a close similarity between the ventral canal cell and the egg. The similarity in fine structure of these cells provides support for the idea that the ventral canal cell is an abortive egg.

ISSN:0373-6687    

DOI:10.1179/jbr.1982.12.2.293

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

AbstractChlorophyll concentrations and a/b ratios of 31 moss species in 16 families collected from various habitats in Kansas were lower than those of most higher vascular plants. Most of the mosses examined had higher chlorophyll concentrations and lower chlorophyll a/b ratios when collected from habitats with low solar irradiance, relative to mosses collected from habitats characterized by high irradiance. This was true for mosses collected from under a forest canopy compared with those collected from exposed sandstone outcrops, and for the same populations of mosses collected before and after forest canopy closure. Such changes in the characteristics of the light-harvesting pigment system appear to represent adaptations enhancing the efficiency of light capture.

ISSN:0373-6687    

DOI:10.1179/jbr.1982.12.2.297

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

ISSN:0373-6687    

DOI:10.1179/jbr.1982.12.2.305

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor