摘要:

AbstractThree case studies are presented to prove that different ontogenetic patterns can produce similar morphologies. In Case I, it is shown that differences in leaf insertion and branch ontogeny between frullanioid and lejeuneoid lines are correlated with distinctive sequences of division in the apical derivatives. Case II demonstrates that the progression to distichy involves different mechanisms in mosses and liverworts. ThatTakakiais uniquely different from all other extant bryophytes and possesses a generalized meristem, rather than an apical cell system, is proven in Case III. Developmental similarities betweenTakakiaand certain primitive tracheophytes are noted, and the division Takakiophyta is established for this truly phylogenetically isolated archegoniate. A coupling of palaeobotanical data about Silurian/Devonian terrestrial floras with the morphogenetic divergences that exist between liverworts, hornworts, mosses, takakiophytes and tracheophytes are seen to support a polyphyletic origin of archegoniates.

ISSN:0373-6687    

DOI:10.1179/jbr.1986.14.1.1

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

AbstractWithin the bryophytes scanning electron microscopy has revealed an abundance of surface features useful in elucidating affinities at generic and specific levels. Appraisal of the broader systematic significance of such data requires transmission electron microscope (TEM) studies of the underlying developmental processes. TEM has made an incisive contribution to the understanding of interrelationships between bryophytes, charalian green algae and tracheophytes. New ultrastructural information should be incorporated into modern schemes of bryophytic classification. The presence of proximal triplet extensions to the two flagellar bases in the spermatids of bryophytes is the only attribute at the ultrastructural level which draws mosses, hepatics and Anthocerotae together. Although cellular organization is basically similar to that in tracheophytes, an increasing list of cytological features and developmental processes peculiar to each of these groups is strongly indicative of wide phyletic differences and also rules direct lines of descent between charalian algae and vascular plants.

ISSN:0373-6687    

DOI:10.1179/jbr.1986.14.1.25

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

AbstractCytological interpretation of bryophyte phylogeny is closely concerned with reproductive behaviour. The development of structural sex specific chromosomes differing only in that the Y includes more heterochromatinsensu latothan the X is indicative of monoecism having preceded dioecism in mosses (Bryophyta or Musci) and liverworts (Hepatophyta) at the lowest level of chromosome number now known. Insufficient data preclude similar analysis of the Anthocerotophyta. Evolution within the Musci has involved a significant degree of polyploidy as well as aneuploidy, with dioecy having arisen again at the level ofn= 2x, the effects of which are seen in the less widespread evidence of subsequent polyploidy. Numerical change among the chromosomes of the Hepatophyta is almost completely confined to very limited polyploidy and is attributed to the early establishment of dioecy at the level ofn= 8, 9 and 10, infrequent sexual reproduction and extensive clonal development. C-, Q-, N- and Hoechst 33258-banding, however, suggest that evolution within liverworts is continuing in hitherto unsuspected ways. Thus, there are pronounced cytological differences betweenPlagiochila porelloides(n= 9) andP. asplenioides(n= 9) and considerable molecular differences between the constitutive heterochromatin ofPellia epiphylla(n= 9) andP. neesiana(n= 8+X/N). It is also suggested that neitherPlagiochila britannica(n= 18) norPellia borealis(n= 18) is an autodiploid of recent origin and that at least the former may be an allopolyploid. All these findings are discussed in the context of related groups of green algae and of pteridophytes.

ISSN:0373-6687    

DOI:10.1179/jbr.1986.14.1.43

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

AbstractThe first attempt to relate the chemical constituents of algae, bryophytes and pteridophytes to evolutionary processes has been made. There are no apparent chemical affinities between green algae and bryophytes, nor between the Hepaticae, Musci and Anthocerotae. The Musci are rather close to the pteridophytes from the point of view of the presence of common triterpenoids. The Hepaticae and the Musci could have originated from different ancestors. The Hepaticae seem to be chemically most nearly related to the Phaeophyceae amongst marine algae, as both groups elaborate structurally and chiroptically very similar terpenoids and closely-related aromatic compounds.

ISSN:0373-6687    

DOI:10.1179/jbr.1986.14.1.59

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

AbstractRecent empirical advances in bryophyte systematics have been made in the discovery and detailed study of new characters. However, theoretical considerations have not kept pace. Proper attention has not been paid to how these new characters can be used to discover relationships among groups and produce classifications. Recent cladistic studies of the relationships of the major groups of bryophytes have demonstrated the feasibility and usefulness of an approach to phylogenetic systematics derived from the works of Hennig. A Hennigian approach attempts to find the particular hierarchical level at which a given character is a homology (i.e. a synapomorphy or shared, derived character), relationships are established by searching for congruent patterns of homologies, and the resulting hierarchical scheme is used as the basis for a classification. Such an approach provides a rigorous and explicit logic for investigating phylogeny and recognizing natural, historically discrete taxa. The theoretical advantages of a Hennigian approach are discussed and illustrated by examining the congruence of new characters data with preliminary cladograms of the major bryophyte groups.

ISSN:0373-6687    

DOI:10.1179/jbr.1986.14.1.71

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

AbstractThe origin of bryophytes is discussed and it is concluded that at our present level of knowledge it is impossible to say whether they are monophyletic or polyphyletic. It is recommended that for the sake of taxonomic stability they are treated as a single division. It is also concluded that views on phylogeny within the Hepaticae, Anthocerotae and Bryopsida are entirely speculative and that more refined levels of analysis may lead to improvements in classification but not in our knowledge of bryophyte phylogeny.

ISSN:0373-6687    

DOI:10.1179/jbr.1986.14.1.83

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

AbstractEpipterygium tozeri(Grev.) Lindb., a moss with a mainly Mediterranean distribution has two means of vegetative propagation. These are described and the European and worldwide distribution is discussed.Epipterygium rigidumLindb. is reduced to synonymy withE. tozeri.

ISSN:0373-6687    

DOI:10.1179/jbr.1986.14.1.91

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

AbstractAnomobryum polysetumShaw is described on the basis of a specimen collected in 1973 in Durango, Mexico by F. D. Bowers, C. Delgadillo, and P. Somers. This species is distinguished from its congenerics by a minute stature, polysetous inflorescences, and rudimentary peristome.

ISSN:0373-6687    

DOI:10.1179/jbr.1986.14.1.99

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

AbstractTouwia laticostatais proposed as a new genus and species of the Neckeraceae, subfamily Thamnobryoideae. It is an aquatic moss characterized by very small, lanceolate to oblong-Ianceolate, erect-spreading to spreading leaves with very strong, percurrent costa that occupies almost⅓the width of the lamina and lamina cells rhomboidal above and becoming elongate towards the base.

ISSN:0373-6687    

DOI:10.1179/jbr.1986.14.1.103

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

AbstractSciaromium lacustreHerz.&Rich.inRich. from Peru is misplaced inSciaromiumand a new genus,Richardsiopsis, is erected to accommodate it.Richardsiopsisis considered most closely related toDonrichardsia macroneuron(Grout) Crum&Anderson from Texas on the basis of their similar gametophyte characters including the strong costa, oblong-rhomboidal to linear-flexuose, prorate lamina cells which are partly arranged in pluristratose strands and foliose, suborbicular, broadly rounded at the apex pseudoparaphyllia.

ISSN:0373-6687    

DOI:10.1179/jbr.1986.14.1.109

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor