摘要:

Ceratopteris pteridoidesis an inbreeding species. Intralocus homozygosity is deduced from the almost total absence of genetic load (recessive deleterious and lethal genes) in sporophytes from natural populations, and from gametangial sequences which indicate intragametophytic selfing. This mating system and the profound capacity of the species for vegetative reproduction, coupled with the small size and geographical isolation of many populations, strongly support the hypothesis of individual homozygosity. However, polymorphism is exhibited both within and between populations in specific, genetically mediated, gametophytic characteristics. The population genetic structure ofC. pteridoidesis similar to other inbreeding species.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1981.tb00125.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SEM has made possible a detailed re‐examination of the thecal plates of marine dinoflagellates belonging to theDiplopsalisgroup which have been collected in an extensive survey of the seas around the British Isles. Six genera are recognized:Diplopsalis, Diplopsalopsis, Dissodium, Oblea, Zygabikodiniumand die new genus and speciesBoreadinium pisiformisDodge 8c Hermes. The confused taxonomic history of the group is discussed, the valid species are listed and a key for the identification of the genera is give

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1981.tb00126.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

The ovule primordium ofCostusis trizonate and both its integuments are dermally initiated. With other evidence, this strongly suggests that most, if not all, monocotyledons have dermally initiated integuments, indicating a derived status. The mature seed coat ofCostusis completely formed by the outer integument and its principal mechanical layer is the endotesta.The seed ofCostushas an aril, an operculum and a micropylar collar. These structures, characteristic of zingiberalean seeds, are each initiated in a different, specific cell layer of the exostome. The aril is completely dermally initiated. The parenchymatic part of the operculum and the micropylar collar are of dual origin, namely dermal at me integumentary region and subdermal at the raphe.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1981.tb00127.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

The outer tepal and stamen primordia arise as secondary primordia on the outer tepal‐stamenprimordia, which are formed on the floral apex. The inner tepal primordia are formed directly on the floral apex. All the floral appendages are initiated in the second tunica layer and are homologous with regard to their origin and early development. A short perianth tube is formed as a result of intercalary growth in the common bases of the tepal primordia. The intercalary growth in the fused bases of the floral appendages elevates the peripheral zone. The floral apex thus appears as a shallow cup. Further intercalary growth results in the formation of an inferior ovary. The ovules are initiated as outgrowths on placental ridges from the lateral ovary wall, the trilocular appearance being the result of secondary cohesion of the parietal placenta

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1981.tb00128.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Petal structure and the distribution of pigments in petals were studied in relation to the functional anatomy of petals and the ways in which petals absorb and reflect light. We examined 201 species from 60 angiosperm families. Anthocyanins, betalains and ultraviolet‐absorbing flavonoids were normally confined to the epidermal cells, occurring in solution in the vacuole; carotenoids were found in the epidermis and in smaller quantities in the mesophyll, normally in chromoplasts. In a few species, mainly blue‐flowered members of the Boraginaceae and Liliaceae‐Scilleae, anthocyanins were confined to the mesophyll.Six basic kinds of petal epidermis anatomy were found, sometimes in combination; papillate (112 species) and multiple‐papillate (13 species), in which the conical‐papillate form of the cells traps incident light and scatters emergent light, with surface striations aiding these functions in many cases; reversed‐papillate (4 species), multiple reversed‐papillate (29 species), lenticular (32 species) and flat (11 species), all with surface striations in some cases. Light is usually reflected from petals mainly by an aerenchymatous unpigmented reflective mesophyll; in certain species this is replaced by a reflective layer of starch grains in the up

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1981.tb00129.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1981.tb00130.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1981.tb00125a.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY