摘要:

Hybrid poplar plants were exposed to 0.5 ppm SO2, 0.25 ppm O3or 0.5 ppm SO2+ 0.25 ppm O3, 12 hr/day for 24 days to ascertain their effects on leaf growth and abscission. The data revealed that both O3alone and O3+ SO2promoted leaf abscission, while SO2alone had no effect. Leaf area and dry weight were reduced while leaf abscission was stimulated by ozone fumigation. The interaction found between SO2and O3, with all the parameters measured, was an antagonistic relationship in which SO2reduced the toxic effect of ozone. The data analyzed, in relation to leaf position, demonstrated that ozone did not affect development of the six youngest rapidly growing leaves. However, ozone significantly reduced both leaf area and leaf weight, at later stages of development.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1980.tb07732.x

出版商:Wiley    

年代:1980

数据来源: WILEY

摘要:

Traditional treatments ofAsterwere found unsatisfactory in predicting cytological and morphological characteristics of members of various subgenera, sections and subsections of different authors. A realignment of species into these infrageneric categories is presented and is based on sets of shared morphological characteristics of roots or rhizomes, leaves, and phyllaries. Eight subgenera are recognised inAster. SubgenusAsteris divided into five sections on morphological characteristics: three have X = 9, one has X = 8 and one has X = 7. SubgenusAstersectionDumosihas been redefined and contains all the X = 8 species. Ten X = 5 species and one X = 4 species previously classified in up to six sections of subgenusAsterwere found to be morphologically and cytologically related to each other, but unrelated to the other species ofAster. These eleven species have been assigned to the genusLasalleasensu Semple&Brouillet.Lasalleahas been divided in sections and subsections with new combinations presented in this paper.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1980.tb07733.x

出版商:Wiley    

年代:1980

数据来源: WILEY

摘要:

Chromosome numbers were determined from more than 241 populations of 46 species and five interspecific hybrids ofAsterL. (X = 9, 8, 7) and from 48 populations of nine species and one interspecific hybrid of the redefined genusLasalleaGreene (X = 5). Seventeen first reports are listed forAsterand four forLasallea. The Nucleolar Organizer Region chromosome of the species ofAsterexamined had a satellite either equal to or longer than the short arm region, while all nine species ofLasalleahad a very small satellite. The retention of the species of subg.Oxytripolium(X = 5) inAsterwas found questionable on cytological grounds, and it was done so for nomenclatural reasons only.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1980.tb07734.x

出版商:Wiley    

年代:1980

数据来源: WILEY

摘要:

Morphological variation in color of female cones in white fir,Abies concolor, is postulated to have adaptive value. The purple variant is only found in one part of the range of white fir where it grows at high elevations. In addition, the frequency of purple cones increases with increasing elevation, suggesting a thermoregulatory function for the purple variant in the cold habitats found at high elevations. Temperature measurements support this hypothesis: purple cones attain higher internal temperatures than do green cones of comparable size. Cone diameter may, in fact, be correlated with cone color but definitive evidence is lacking. Alternative hypotheses are offered which may also be important in maintaining the presence of the purple variant at high elevations. It is suggested that other characters associated with purple cones may place them at a competitive disadvantage at lower elevations.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1980.tb07735.x

出版商:Wiley    

年代:1980

数据来源: WILEY

摘要:

Claytonia virginicahas a regular flower with two sepals, five petals with an equal number of stamens in positions opposite the petals and a many‐seeded tricarpellate gynoecium with basal placentation. The flower has been interpreted as uniseriate, the putative sepals as bracts and the corolla as modified calyx lobes. Anatomical and developmental studies were undertaken to find evidence for the existence of vestigial or rudimentary parts whose existence would illuminate the true nature of the flower. Vascular and epidermal anatomy of sepals are both similar to that of leaves. Corolla and androecium develop basipetally and petals and stamens share common vascular traces in the lower part of the receptacle. Thus, in terms of both anatomy and development, evidence supports the conclusion that the perianth is essentially biseriate. Vestigial or rudimentary parts are not present which would alter the manifest design of the mature flower.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1980.tb07736.x

出版商:Wiley    

年代:1980

数据来源: WILEY

摘要:

Numerous anatomically preserved ovules assignable to the genusMitrospermumhave been discovered in Upper Pennsylvanian sediments of Eastern Ohio. Although basically similar toMitrospermum compressum, the newly discovered specimens exhibit several consistent differences. Ovules are strongly platyspermic, up to 4.2 mm long, 4.0 mm wide, and 0.6 mm thick. In the minor plane, ovules are broadest at the base and taper toward the micropyle. The integument exhibits three topographic regions: endotesta, sclerotesta, and sarcotesta. The sarcotesta is extremely broad in the major plane, where it forms two membranous wings. A single terete vascular bundle enters the base of the ovule, traverses the integument, and divides to form two integumentary bundles and a conspicuous nucellar platform. Integumentary bundles extend toward the tip of the ovule at the margin of the sarcotesta and sclerotesta. A pollen chamber with a prominent nucellar beak is delimited at the tip of the nucellus. Consistent differences in vascularization, size, nature of the seed base, features of the pollen chamber, and the Late Pennsylvanian age demonstrate that the specimens represent a distinct species. The discovery of these ovules extends the stratigraphic range ofMitrospermumto the Upper Pennsylvanian of Ohio.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1980.tb07737.x

出版商:Wiley    

年代:1980

数据来源: WILEY

摘要:

As part of an investigation on the potential of salt marshes to act as natural waste treatment systems, we are studying the cycling of heavy metals in Great Sippewissett Marsh, Massachusetts. For the last 7 yr, varying doses of fertilizer containing sewage sludge have been added to experimental plots. Changes in metal levels in the sediment, grasses, and animals have been monitored. Marsh sediments retained 20‐35% Cd, 20‐50% Cr, 60‐100% Cu, 55‐100% Pb, 80‐100% Fe, 55‐60% Mn and 20‐45% of the Zn added in the fertilizer. When compared with low marsh, high marsh areas retained a significantly greater fraction of all the added metals except Mn.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1980.tb07738.x

出版商:Wiley    

年代:1980

数据来源: WILEY

摘要:

The role of Pacific coast marsh plants as vectors in the flux of trace metals was studied in natural and perturbated situations. The flux of Cr, Cu, Fe, Mg, Sr, and Zn were studied in natural stands ofCarex lyngbyei, Distichlis spicata, Potentilla pacifica, andSalicornia virginica. Seasonal fluxes of trace metals into the shoots of the living plants were measured as was their transfer to the dead plant community through mortality. Disappearance from the latter community (through fragmentation, leaching and excretion) was calculated. Seasonal data were summed to produce annual input‐output budgets. The flux varied from 3 mg/m2for Cr in a stand ofPotentilla pacificato 15,000 mg/m2for Fe inCarex lyngbyei.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1980.tb07739.x

出版商:Wiley    

年代:1980

数据来源: WILEY

摘要:

The present study was designed to determine the uptake and release rates of various trace metal cations by turtle grass and its community in order to provide the coefficients of our previously described computer model intended to simulate trace metal cycling in subtropical and tropical estuaries. The site of uptake inThalassiawas also examined.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1980.tb07740.x

出版商:Wiley    

年代:1980

数据来源: WILEY

摘要:

Significant (P<0.005) differences in Mn, Fe, Cu and Zn concentrations were found in different parts of eelgrass plants; i.e., roots and rhizomes, live blades, attached dead blades, and detritus. Imported vs. exported suspended particles of eelgrass blades did not differ in Mn, Fe, Cu or Zn content. Significant location effects, which varied with the type of plant tissue, were noted for Mn, Fe, Cu and Zn for three grass beds in the vicinity of Beaufort, NC. In simplified Mn, Fe, Cu and Zn budgets, eelgrass biomass is the largest biological reservoir, while eelgrass growth, senescence, and decomposition constitute the largest biological flux of these elements in this ecosystem.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1980.tb07741.x

出版商:Wiley    

年代:1980

数据来源: WILEY