摘要:

SummaryThe discovery of numerous fossil plants in recent years, together with the application of new techniques directed at understanding the total biology of the organism, has resulted in the modification of some ideas pertaining to the origin of land plants. Several of these lines of evidence strongly suggest the presence of a diverse terrestrial flora significantly earlier than the Upper Silurian bench mark currently used for the first appearance of plants with vascular tissue.

ISSN:0040-0262    

DOI:10.2307/1219982

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryFollowing a review of previous classifications, a revised scheme is presented for the 155 genera of Pooideae, derived via numerical analyses of original and compiled morphological and anatomical data and consideration of additional evidence. The subfamily is divided into two newly described supertribes, Poanae and Triticanae. These are further subdivided into the following tribes, all fully described: Poeae, Seslerieae, Meliceae, Aveneae and Agrostideae (in Poanae) and Triticeae, Bromeae and Brachypodieae (in Triticanae). The Aveneae are more narrowly circumscribed than is usual. The data employed in the numerical analyses are available, on microfiche, as full English descriptions.

ISSN:0040-0262    

DOI:10.2307/1219983

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryPreparatory to the use of volatile oils in systematic studies of Australian rainforest trees, a number of different techniques for handling volatile oil data are reviewed. Compared are two different schemes of character weighting (unweighted and F‐weighted), three different schemes of standardisation (unstandardised, standardisation by range, standardisation by standard deviation), and three different distance measures (Squared Euclidean Distance, Euclidean Distance, Manhattan Metric distance). It is determined empirically that, for volatile oil data, where weighting is both possible and valid, a combination of standardisation and weighting proves most effective; on the other hand, if weighting is not possible, standardisation should not be undertaken. Euclidean Distance and Manhattan Metric distance prove to be the best distance measures.

ISSN:0040-0262    

DOI:10.2307/1219984

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryAn outline and index to supplement Takhtajan's 1980 classification of flowering plants is presented.

ISSN:0040-0262    

DOI:10.2307/1219985

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

AbstractEpiblast length and shape were examined in 39 species of the Stipeae, 29 of which are native to North America. In most species ofStipaexamined the epiblast equalled or exceeded the coleoptile and was acute with or without a small V‐shaped notch at the apex. In contrast, in most species ofOryzopsisthe epiblast extended no more than three‐quarters of the way up the coleoptile and was more or less truncate. Two other characters that tended to differ betweenStipaandOryzopsiswere the overall shape of the embryo as seen in ventral view and the position of the tip of the coleorhiza. InOryzopsisthe embryo tended to be broader (length/width 1.0‐1.6) than inStipa(length/width 1.5‐3.7) and the tip of the coleorhiza higher with respect to the base of the embryo.Some taxonomically significant variation was seen within each genus. The species ofStipasect.Hesperostipaare distinguished by a deep, parallel‐sided apical notch. The placement ofS. webberiandS. hendersoniiinStiparather thanOryzopsiswas supported by the characters considered here. The two species ofNassellaexamined were stipoid in their epiblast characters, but their over‐all shape and the position of the coleorhiza were oryzopsoid. The only species ofPiptochaetiumexamined,P. pringlei,was typically stipoid in the characters examined.

ISSN:0040-0262    

DOI:10.2307/1219986

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryA palynological study ofAchatocarpusTriana andPhaulothamnusA. Gray utilizing structural data from transmission electron microscopy (TEM), reinforces their close relationship as suggested by scanning electron microscopy (SEM) and supports family status as Achatocarpaceae. Both genera are known to have the betalain pigments and protein‐type sieve tube plastid which characterize the order Centrospermae. Affinities within the Centrospermae remain uncertain.

ISSN:0040-0262    

DOI:10.2307/1219987

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryThe characters used in a recent phylogenetic analysis of land plants to derive the “Gneticae” and flowering plants from a common ancestor are critically evaluated. In our opinion, these characters are not homologous in the two groups and cannot be used in such a fashion. A cladistic analysis of seed plants (or land plants) is a worthwhile endeavor, but requires careful consideration of the homologous nature of the characters that are utilized in such an analysis.

ISSN:0040-0262    

DOI:10.2307/1219988

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryUltrastructural features of the flagellar apparatus in green algae and land plants seem to be of considerable phylogenetic significance. Based on functional considerations details of the flagellar apparatus can be used to construct tentative lines of evolution within the green algae. An “ancestral” asymmetric zooflagellate possibly gave rise to a green unicell after a primary endosymbiotic event involving a green prokaryote. During the transition from phagotrophic to phototrophic nutrition in most green algae (the Chlorophyceae and Ulvaphyceae sensu Stewart&Mattox and most Prasinophyceae sensu Christensen) the original asymmetric flagellar apparatus was transformed into a 180° rotational symmetric flagellar apparatus with 4 flagella and a flagellar root system of the X‐2‐X‐2‐type. Most significant in this transition was presumably the evolution of the phototactic apparatus and of an apical flagellar groove. In the Charophyceae sensu Stewart&Mattox (including those green algae related to the ancestry of the archegoniate land plants) the early transition towards a terrestrial life, lack of an eyespot apparatus and development of a special type of oogamy possibly led to the evolution of the unilateral flagellar root in these organisms. It is suggested that the evolution of the unilateral MLS‐root in the Charophyceae sensu Stewart&Mattox can be traced back to an “ancestral green flagellate” before the evolution of the typical X‐2‐X‐2 flagellar root system. A tentative evolutionary scheme of the green algae mainly based on motile cell structure and mitotic and cytokinetic mechanisms is presented.

ISSN:0040-0262    

DOI:10.2307/1219989

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryA procedure has been described for evaluating linkage between objects which are represented by points in a multi‐dimensional space in terms of overlap between replicates. An illustration of the procedure demonstrated its usefulness for the recognition and analysis of innate group structure.

ISSN:0040-0262    

DOI:10.2307/1219990

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryA modified polyclave keying method is described which employs one card per character rather than character state. This can allow a great reduction in the total number of cards required for keying, along with a lessened need to keep the cards carefully sorted. This allows practical field use of the key. The keying deck is an attribute type with up to 78 taxa and 10 character states or 156 taxa and 5 character states per card. Identifications are made by overlapping the character cards on an identification board. Additional cards or decks are required when the number of character states is greater than 10 (or five in the 156 taxa version) or the number of taxa exceeds 78 (156 in the larger version).

ISSN:0040-0262    

DOI:10.2307/1219991

出版商:Wiley    

年代:2019

数据来源: WILEY