摘要:

LeymusHochst., a segregate genus of Triticeae, can be recognized morphologically and genomically. Its members exhibit all or all but one of the following morphological characterstics: rhizomatous habit; unawned, short, often stiffly subulate, glumes that tend to lie opposite the sides rather than the midveins of the lemmas; unawned, or only shortly awned, lemmas; and long anthers. They are all polyploids based on the same pair of genomes, one fromPsathyrostachysand the other fromThinopyrum.Fourteen species occur in North America, including two interspecific hybrids. One new subspecies is described,L. salinussubsp.mojavensis.A key, descriptions, and distribution maps are given. In addition, one new hybrid genus, ×Leytesion,and several new combinations are published to accommodate the naturally occurring intergeneric hybrids involvingLeymus.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1984.tb14168.x

出版商:Wiley    

年代:1984

数据来源: WILEY

摘要:

Cuticular or “paper” coal‐shale is a local deposit of an organic‐rich, highly clastic rock, with abundant leaf and stem cuticles, associated with the Upper Block Coal Member in Parke County, Indiana. Fresh blocks of cuticular coal can be split along bedding surfaces to reveal a fossil flora of low diversity, dominated by pteridosperms and lycopods, with minor amounts of ferns and sphenopsids.Karinopterisis a subdominant component of this flora and the great abundance of well‐preserved cuticles of this plant allows for a reconstruction of its frond and growth habit.Karinopterisappears to have been a vine, indicative of structural diversity in the plant assemblage. The plant assemblage of the cuticular coal is dissimilar to most midwestern coal‐ball floras of slightly younger age. This is probably a result of the depositional setting in an upper deltaic‐fluvial dominated environment.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1984.tb14169.x

出版商:Wiley    

年代:1984

数据来源: WILEY

摘要:

In aseptically cultured rhizome segments of the aquatic fernMarsilea quadrifolia,the addition of abscisic acid (ABA) to the liquid medium induced development of morphological characteristics distinctive to the land form of the plant. The land‐form characteristics induced by ABA included a change in leaf morphology, an increase in the surface area of leaflets, differentiation of stomata and trichomes, elongation of petioles and roots, development of lateral roots, shortening of rhizome, and reduction in the number of leaves and roots formed on each plant.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1984.tb14170.x

出版商:Wiley    

年代:1984

数据来源: WILEY

摘要:

A comparative methodological study was made of the fine structure of apical cortical cells in excised radicles from cotton (Gossypium hirsutumL. var M‐8) seeds. Radicles from dry seed had 12% moisture content and were prepared for electron microscopy using several different techniques. These included different methods of chemical fixation or freeze‐fracture and etching of unfixed tissue for transmission electron microscopy (TEM) and cryofracturing of fixed and dehydrated radicles for scanning electron microscopy (SEM). Cortical cells had a similar appearance regardless of the method used in tissue preparation. Cell walls had a pronounced waviness which was particularly evident in SEM images of cells lining the elongated intercellular air spaces. The plasma membrane (PM) delimited the cytoplasm of each cell as an intact unit membrane. Single layers of tightly‐packed lipid bodies (LB) were apposed to the PM and protein bodies (PB). Distension of cells, membranous organelles and LB was observed in radicles fixed by immersion in aqueous solutions, suggesting that a certain amount of hydration occurred during fixation. This interpretation was supported by the compact appearance of cells and organelles in tissue prepared by freeze‐etch or vapor fixation. We conclude that freeze‐fracture and etching of unfixed tissue provided the best information for cell morphology and structure of membranes and organelles in dry tissue. Complementary data on the fine details of nuclei and cytoplasmic organelles were best observed with TEM of fixed tissue. These data when viewed collectively indicate the advantage of using several techniques to obtain analogous and complementary information essential for establishing a baseline level of information on the fine structure of cells in dry tissue.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1984.tb14171.x

出版商:Wiley    

年代:1984

数据来源: WILEY

摘要:

Species of the Marsileaceae represent a unique group of pteridophytes of uncertain origin. The polyphenolic profiles of representative species, which include flavonol‐3‐O‐mono‐ and diglycosides, C‐glycosylflavones and C‐glycosylxanthones, have chemical features in common with the primitive leptosporangiate ferns, especially the Hymenophyllaceae. Intergeneric relationships in the family based on morphology, cytology, fossil evidence and polyphenolic profiles are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1984.tb14172.x

出版商:Wiley    

年代:1984

数据来源: WILEY

摘要:

Roots ofTypha latifoliaL. exposed to Fe2+under reduced conditions in solution culture developed visible coatings (plaques) of an oxidized Fe compound that extended as much as 15‐17 μm into the rhizosphere. Iron concentrations were significantly less and discoloration was not apparent on the surface of roots exposed to Fe‐(BPDS)3, Fe3+, Fe‐EDDHA, and Fe‐EDTA. The extent of plaque formation increased with the concentration of Fe2+in solution and with pH of the solution in the range of 3.0 to 4.6. Above pH 4.6, oxidation of Fe2+in the culture solution may have reduced precipitation of Fe on the root surface. Plaque development was most extensive approximately 1.0 cm from the root tip, but all root surfaces showed some Fe staining. Scanning electron micrographs of plaqued roots, grown both in solution culture and in the field, provided support for a model of cast formation by oxidation and precipitation of Fe on external cell surfaces.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1984.tb14173.x

出版商:Wiley    

年代:1984

数据来源: WILEY

摘要:

Soybeans have a wet stigma overtopped by a pellicle that originates from the cuticle. There are numerous exudate‐filled, axially oriented channels between cells of the transmitting tissue in the stigma and style. Pollen tubes grow in these channels and receive nutrition and mechanical guidance. Transmitting‐tissue cells of the obturator are secretory also, but the obturator in soybean does not appear to control direction of pollen tube growth mechanically. The significant function of transmitting tissue in soybeans is to provide nutrition and to control direction of pollen tube growth.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1984.tb14174.x

出版商:Wiley    

年代:1984

数据来源: WILEY

摘要:

Osmorhiza longistylisis an herbaceous perennial that grows in woodlands of eastern and central North America. In northcentral Kentucky seeds ripen in early to mid July, and dispersal begins in September and October. Although most of the seeds are shed during late autumn and winter, some remain on the dead shoots for up to 18 months. Seeds are dormant at maturity due to an underdeveloped embryo. Embryos grew at low (5 C) temperatures, but only after seeds were given a period of warm (30/15 C) stratification. With an increase in the length of the warm treatment, there was an increase in the number of embryos that grew to full length during a 12‐wk period at 5 C and an increase in the percentage of seeds that germinated. Seeds given 12 wk of warm stratification required more than 8 wk at 5 C to overcome dormancy. Embryos in freshly‐matured seeds averaged 0.60 mm long, but those in seeds given 12 wk warm plus 12 wk cold stratification averaged 8.86 mm. Lengths of embryos of seeds kept moist at 30/15 and 5 C for 24 wk averaged 0.63 and 0.89 mm, respectively. Regardless of age and dispersal time, imbibed seeds must be exposed to high (i.e., summer or autumn) and then to low (i.e., winter) temperatures before they will germinate. Consequently, germination occurs only in spring.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1984.tb14175.x

出版商:Wiley    

年代:1984

数据来源: WILEY

摘要:

Studies investigating developmental anatomical changes inLayia platyglossaexposed to four CO2levels—0.03, 0.07, 0.14, 0.21%—revealed significant differences in vascular tissue development in leaf and stem. Lateral root vascular structures were unchanged at the elevated CO2concentrations. Plastochron intervals indicated higher growth rates with increasing CO2levels. Primary differentiation of vascular and ground tissues in young stems occurred closer to the promeristem at the lower CO2concentrations indicating less rapid growth patterns. Biochemical assays revealed that the contents of nucleic acids and chlorophyll in young leaves were unaffected while the levels of protein increased with elevated CO2concentrations.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1984.tb14176.x

出版商:Wiley    

年代:1984

数据来源: WILEY

摘要:

The floral ecology of a central Maine population ofPlatanthera blephariglottiswas studied during the 1979–1981 flowering seasons. Although this species possesses characteristics typical of moth‐pollinated plants, only diurnal pollinators were documented, primarily Hesperiidae, Pieridae, and Apidae. Pollinators were scarce throughout the study, yet bagging experiments indicated vectors were necessary for successful capsule set. The average capsule set per plant was lowest (32.2%) in 1979 when 362 plants bloomed and highest in 1980 (80.2%) when 202 plants flowered. Capsule set was found to be limited by pollinator activity. The adaptations ofP. blephariglottis,including sequential flowering, length of receptivity, nectar production and inflorescence size, enable consistently successful reproduction regardless of microhabitat. This species is well‐adapted to reproduce in environments experiencing periods of unfavorable weather and low pollinator abundance.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1984.tb14177.x

出版商:Wiley    

年代:1984

数据来源: WILEY