摘要:

SUMMARYFifteen populations ofAzollawere sampled in the western and north‐eastern parts of The Netherlands. After cultivation under identical conditions in a greenhouse they could be divided into two species which had previously been recorded from The Netherlands under the names ofAzolla filiculoidesLam. andAzolla carolinianaWilld. Populations which appeared to be morphologically intermediate between these two species were eventually found to be trueA. filiculoides. Although identification of certain forms in the field remains difficult, the two species can always be distinguished under a microscope by the number of cells forming the trichomes on the surface of the upper lobe of the leaflets, the septation of the glochidia and the surface structure of the megaspores. Other characteristics which have been reported in the literature are not always consistent. However, well‐developed specimens ofA. filiculoidescan easily be recognised from their general appearance. In the autumn, when the plants become reddish as a result of anthocyanin production,A. filiculoidesturns to a purer red than the plants of the other species which become more browny red. In both species the anthocyanins contain the relatively rare anthocyanidins luteolinidin and apigenidin. Anthocyanin production was found to be influenced by temperature and water composition but not by day‐length. Well‐developed forms ofA. filiculoidesgenerally occur in more eutrophic water than plants of the other species. According to the revised classification of the New World species ofAzollaby Svenson(1944), the Dutch specimens previously referred to asA. carolinianado not belong to this species, but to eitherA. mexicanaPresl orA. microphyllaK

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1977.tb01137.x

年代:1977

数据来源: WILEY

摘要:

SUMMARYThe morphology of two species ofAcrochaetium, provisionally identified asA. polyblastum(Rosenv.) Børg. andA. hallandicum(Kylin) Hamel, is described in some detail. They are shown to be tetrasporophyte and gametophyte respectively in the same life history. Both phases are characterized by the possession of a stellate chromatophore with a central pyrenoid; the tetrasporophyte has a spore which germinates septately and subsequently develops a multicellular filamentous base, the gametophyte has a unicellular base.The sexual cycle is mainly temperature‐controlled, the gametangia being formed under higher temperature than the tetrasporangia. Both generations reproduce asexually by means of monospores, in a wide temperature range.The morphological variability, as affected by different environmental conditions, appears to be very large; moreover there is an ample variation between different clones grown under uniform conditions. General structure of the plant, the type of spore germination in each phase, and cell diameter are the most reliable characters in delimiting the species from other acrochaetioid taxa.The life histories ofAcrochaetiumspecies possessing stellate chromatophores, as exemplified by a number of different species now, show a remarkably uniform pattern, as far as alternation of morphological phases is concerned. It is suggested that characters of the total life history provide a reasonable basis for the systematics of the acrochaetioid alg

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1977.tb01138.x

年代:1977

数据来源: WILEY

摘要:

New taxa and combinations are published here in anticipation of the revision of the Rutaceae‐Pilocarpinae to be published in the near future (thesis, and in Flora Neotropica). Two new combinations of species excluded from subtribe Pilocarpinae are adde

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1977.tb01139.x

年代:1977

数据来源: WILEY

摘要:

SUMMARYLagynion spiniferumn. sp., characterised by delicate spines on its lorica, is described. It was found growing in the mucilage investment ofDraparnaldia plumosacollected from a peat pond in the Western part of The Netherlands.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1977.tb01140.x

年代:1977

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1977.tb01141.x

年代:1977

数据来源: WILEY