ISSN:0017-3134    

DOI:10.1080/00173139309428972

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

It is generally agreed that the Periplocaceae arose from apocynaceous ancestors. Whether these ancestors were from the Plumerioideae, Cerberoideae or Apocynoideae has long been in dispute. This investigation is a comparative study of the pollen morphology and floral structure of selected genera of Apocynaceae and Periplocaceae.

ISSN:0017-3134    

DOI:10.1080/00173139309428973

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Structures that receive sporopollenin are similar in the pollen grains of a wide variety of angiosperms and in the coniferPinus. These structures are rod-shaped, with a central core that accepts stains strongly and an outer binder zone that only weakly accepts stains. These sporopollenin-accumulating rods are substructures of the exine units we call “tufts”. In many taxa tuft substructures are covered by receptor-independent (extra-tuft) accumulated sporopollenin and surfaces are smooth. We show an example (Quercus coccifera) of the acetolysis resistance of extra-tuft accumulated sporopollenin followed by its removal through oxidation which reveals the tufts.

ISSN:0017-3134    

DOI:10.1080/00173139309428974

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

El-Ghazaly, G. & Chaudhary, R. 1993. Morphology and taxonomic application of orbicules (Ubisch bodies) in the genusEuphorbia. – Grana Suppl. 2: 26–32.

ISSN:0017-3134    

DOI:10.1080/00173139309428975

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Results of the examination of pollen grains of 65 species of eight genera (Cistus, Crocanthemum, Fumana, Halimium, Helianthemum, Hudsonia, Lechea, andTuberaria) of the family Cistaceae Juss, are presented. A set of morphological characters including the type of aperture structure, the shape and size of the pollen grains and the exine structure and sculpturing, allowed the recognition of six pollen types (Cistustype,Crocanthemumtype,Fumanatype,Helianthemumtype,Hudsoniatype andLecheatype). These six types of pollen grain form three groups, which correspond well with the three main evolutionary trends of the tribes within the family. The palynological data presented here agrees well with the systems suggested by Janchen (1925) and Takhtajan (1987) in which the family Cistaceae is divided into three tribes, namely Cisteae, Hudsonieae and Lechidieae.

ISSN:0017-3134    

DOI:10.1080/00173139309428976

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Three special types of pollen geometric aspects, the polyhedric lophate-lacunar grains of the Asteraceae, the 2-colporate rotated symmetric grains of the Acanthaceae, and the pyramidal to prismatic spinules of the Icacinaceae are discussed in this report. The lacunar patterns in four types (Adenoon indicumType,Vernonia anthelminticaType-1 & Type-2, andVernonia monosisType) of 3-colpororate pollen are described by simple mathematical formulae. This evidence shows that the lacunar patterns of lophate grains are controlled by the geometry of spherical surface configurations. The occurrence of two types of lacunar patterns of lophate pollen within a taxon,V. anthelmintica, is supportive of our hypothesis that a few reversible lacunar changes involving addition or suppression of our hypothesis that a few reversible lacunar changes involving addition or suppression of crosswalls may bring about different lacunar patterns. With regard to the 2-colporate rotated symmetric pollen of the tribe Trichanthereae, we underscore here that its physical equilibrium is maintained despite rotation, by the equal number of foveoreticulate bands and a colporus in each rotated hemisphere. The angular spinules are unique as they differ from the common coniform type of pollen spines and spinules. These geometric exine patterns are morphologically distinctive, with differences that can be described mathematically. As such, they provide potentially useful data for phylogenetic analysis.

ISSN:0017-3134    

DOI:10.1080/00173139309428977

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

BowdichiaandPanureaare the only genera in the tribe Sophoreae with psilate pollen. The pollen of the four species recognised in the two genera can be divided into three distinct types: (1) Spheroidal in shape, tricolporate with long colpi (Bowdichia); (2) Oblate in shape with three very short colpi or pori (Panurea bowdichioides); (3) Cuboid in shape, tetracolpate (Panurea longifolia). The exine stratification ofBowdichiais very distinctive with a thick tectum, short columellae and thick foot layer. The two species ofPanureahave a similar exine stratification with long columellae and much thinner tectum and foot layer. Exine stratification provides additional evidence to support the generic relationships ofP. bowdichioides, a new species, which has some floral characters similar toBowdichiaand simple leaves ofPanurea. Pollen morphology provides additional evidence to support the view thatBowdichiaandPanureahave no very close relatives in the Sophoreae.

ISSN:0017-3134    

DOI:10.1080/00173139309428978

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

We report features of sporoderm development ofCinnamomum verumPresl. from the vacuolated stage of microspores through pollen grain maturity. Before microspore mitosis the sporoderm consists of spinules and gemmae separated from the cytoplasm by a channeled onciform zone. When the intine forms, after microspore mitosis, it is highly fimbriated in profile. The surface of the exine, (spinules and gemmae) is covered by a thick (200–300 nm) surface coating. Elements of the surface coating are glycoprotein and connect with filamentous material within the anther loculus. The gemmae may be assumed to increase in number between the microspore period and pollen grain maturity since their frequency per unit area and the surface area of the grains increase. The implication is that sporopollenin is added late as well as early in development. Spinules, gemmae, and straps between gemmae resist acetolysis, but special handling (no rehydration and minimal mechanical flexure) is required in order to retain the spheroidal configuration of exines; otherwise exines are compacted into knot-like masses that are then unidentifiable.

ISSN:0017-3134    

DOI:10.1080/00173139309428979

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

An attempt is made to approach the problem of exine structure determination. Two general hypotheses are suggested using the data of a number of investigators together with the author's own findings. A considerable independence of processes (self-assembly processes) resulting from the physical and chemical properties of a molecular solution in a thin layer.

ISSN:0017-3134    

DOI:10.1080/00173139309428980

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A description is given of fossil pollen of the genusArmeriaWilld. (lines A and B), found for the first time in stratigraphical sections in Byelorus dated to the Alexandrian (Likhvin, Mindel-Riss). The fossil pollen was studied with a scanning electron microscope (SEM), and the same procedure was used to examine four species of recent pollen ofArmeria(two lines) which today grow on the East European Plain (onlyArmeria vulgarisWilld. grows in Byelorus). Descriptions of the recent pollen ofArmeria labradoricaWallr.,A. maritima(Mill.) Willd.,A. scabraPall, et Schult. and A.vulgarisWilld. are given separately for each line. On the basis of the data obtained from the recent pollen, fossil pollen was identified to species. The data allow us to conclude that no less than two species ofArmeriagrew in Byelorus during the Alexandrian Interglacial. They are identified asArmeria vulgaris(lines A and B) and A. aff.scabra(lines A and B). Thus, it has been possible to relate fragmentary pollen spectra from different boreholes and compare them with spectra from the Matveev Rov outcrop which is the stratotype of the Alexandrian Interglacial in Byelorus. It is demonstrated thatArmeriaappeared in the final phases of vegetational evolution during the interglacial, prior to the advance of the Dnieper (Riss) Glaciation. It was also possible to identify even fragments of fossil pollen ofArmeriaby SEM with the help of the keys produced in the parallel SEM study of recent pollen, since the main specific differences are seen in the elements of exine structure.

ISSN:0017-3134    

DOI:10.1080/00173139309428981

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor