摘要:

Nuclear division inP. monticolais in general similar to mitosis in higher organisms. Synchronous division of the nuclei in the dikaryon progresses with clamp development. Mitosis begins with the movement of the centriolar plaques into and under the forming clamp. The pull of the centriolar plaque on the attached nucleolus forms a long strand of nucleolar material. Chromosomes now appear as dense granules at the end of the nucleus proximal to the clamp. At this time the nucleolus moves adjacent to the centriolar plaque and contracted chromosomes. The nuclear membrane at least partially disintegrates, and the nucleolus is released into the cytoplasm where it may persist through telophase. A faintly staining spindle is often observed, and it produces a “double bridge” effect in separating chromatin. Somatic chromosomes are attached together forming strings that appear double and at least partially separated before metaphase.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1971.tb09973.x

出版商:Wiley    

年代:1971

数据来源: WILEY

摘要:

The shoot‐growth rhythm of tropical trees is a little understood phenomenon. Correlations of tree growth with environment, determined from field studies in the tropics, have been largely inconclusive, and few studies have been done under controlled environmental conditions. As an initial part of a project to study shoot‐growth rhythms in tropical trees this paper describes the rhythm inTheobroma cacaoL. An individual shoot passes through alternate periods of growth and dormancy. The growth period is characterized by the expansion of leaves and elongation of the shoot. During dormancy the length of the shoot remains constant, and no new leaves expand. Shoot‐growth rhythm was divided into phases. Dissection of shoot tips from the various phases shows that the total number of leaves and leaf primordia in the shoot apex remains constant during the dormant period and does not increase until the onset of the growth period. This indicates that activity of the apical meristem as well as leaf expansion and shoot elongation are rhythmic. We found that the rhythm of shoot growth persists under controlled environmental conditions and that growth under these conditions is asynchronous, as it appears to be in the field. Our data strongly suggest endogeneity.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1971.tb09974.x

出版商:Wiley    

年代:1971

数据来源: WILEY

摘要:

The final step in the process of conidiation—conidial pigmentation—was studied in the fungusTrichoderma viride. Twenty‐nine auxotrophic, color mutants, isolated from the same green wildtype strain, were paired to produce stable heterokaryons in all possible combinations and grouped according to their complementation behavior. No complementation (green pigmentation) was found in any of the heterokaryons formed by pairs of white (W) mutants. However, these mutants could be separated into two groups with respect to their behavior when paired with yellow (Y) and brown (Br) mutants. WhenWcmutants were paired with any of theYorBrmutants complementation took place. However,Wdmutants displayed this reaction with only one group of yellow mutants (Ya) and not with the other (Yb) nor withBrmutants. In noncomplementing heterokaryons such asYb/Wd, only yellow and white conidia were produced, pigmentation being autonomous. On the other hand, in heterokaryons in which complementation did take place, as for instanceYa/Wd, green as well as white and yellow conidia were produced. Differential sensitivity to UV irradiation was used to show that the green conidia were of eitherWdor Fagenotype, indicating a nonautonomous type of gene action. It is suggested that the genesWc,Ya,YbandBrhave a sequential structural role in the biosynthesis of the green pigment, whileWdcontrols the activity of three (Wc,Yb,Br) of these genes.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1971.tb09975.x

出版商:Wiley    

年代:1971

数据来源: WILEY

摘要:

The cytology and chemistry of three populations of the species complexPityrogramma triangularisfrom Santa Barbara County, California, were studied. The basic chromosome number of these ferns is x = 30, and there are diploids, triploids, and tetraploids. Although gross morphology in the plants is similar, four chemical types are observed when extracts of the external frond pigments are analyzed. Ten of the twelve possible combinations of ploidy level and pigment types have been found. Correlations of spore condition, cytology, and chemistry which indicate either an autotetraploid or allotetraploid derivation of the complex are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1971.tb09976.x

出版商:Wiley    

年代:1971

数据来源: WILEY

摘要:

A new structurally preserved synangiate pollen organ is described from the upper Pennsylvanian (Mattoon Formation) of southeastern Illinois. The specimen ofHalletheca reticulatusgen. et sp. nov. measures approximately 1.5 cm long by approximately 5.0 mm in diam, and consists of five elongate sporangial tubes equidistantly arranged around a solid central column, and embedded in a thin‐walled ground tissue. The vascular system consists of five terete bundles characterized by scalariform tracheids. Sporangia are thick‐walled and contain pollen of theMonoletes‐type. Ultrastructural studies of the pollen grain wall show it to consist of a uniform network of muri which branch and re‐unite to form small lumina. A comparison of the ultrastructure of the pollen grain wall of the new fructification is made with the wall organization found in similar pollen ofDolerotheca. Relationships between the new taxon and other presumed seed fern pollen organs differing in preservation mode are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1971.tb09977.x

出版商:Wiley    

年代:1971

数据来源: WILEY

摘要:

Patterns of silica deposition on the outer epidermal cell walls ofEquisclum arvenseandE. hycmalcvar.affinewere examined by means of electron microprobe analysis. Silica is deposited primarily in discrete knobs and rosettes on the epidermal surface inE. arvenseand essentially in a uniform pattern on and in the entire outer epidermal cell walls ofE. hyemalevar.affine. This markedly contrasts with patterns of silica deposition in internodal epidermal cells ofAvena saliva(Gramineae) where silica is deposited primarily in cell walls and cell lumina, and to a much lesser extent, on the outer epidermal surface. Semi‐quantitative analysis with the electron microprobe shows that in intercalary meristematic cells ofE. aruense, silicon is not present in any cells, but that in mature epidermal cells above the intercalary meristem it is present in significant quantities. The study thus suggests that silica deposition must be a very rapid process inEquisclumandAvena.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1971.tb09978.x

出版商:Wiley    

年代:1971

数据来源: WILEY

摘要:

The stigmatic exudate of sweetpotato, when removed with organic solvents, consisted chiefly of lipid and phenolic compounds. Only traces of sugar were obtained. The esterified lipids were similar in chain length to capric and lauric acids. The two prinicpal phenolic compounds have UV absorption peaks, and bathochromic shifts on ionization with NaOH similar to those of esters of caffeic acid. On acid hydrolysis, caffeic acid was obtained from these and from three minor phenolic compounds. From two of the minor phenolic compounds, glucose was released by hydrolysis. The phenolic content of stigmas increased up to 20–24 hr before anthesis, and then gradually decreased. Neither compatible nor incompatible pollination affects the amount or composition of the stigmatic exudate.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1971.tb09979.x

出版商:Wiley    

年代:1971

数据来源: WILEY

摘要:

Anemia colimensis, the most primitive known species of the genus, has been investigated with respect to gametophyte development and morphology. In the early stages the thalli are in general similar to those of species ofAnemiawhich are charcterized by the development of an initially lateral marginal meristem. One significant difference was noted in the frequent appearance of meristematic zones on both sides of the young plate. One of these becomes the marginal meristem; the other eventually ceases activity. The mature gametophyte is a spherical cushion of complex organization, the result of extreme ruffling of the wings of the thallus and the remarkable abundance of filamentous outgrowths and deep lobing of the wings. This form of gametophyte is unique among the investigated anemias. It is proposed that the formation of a lateral meristem, the “Ceratopteris type” of prothallial development, is primitive inAnemiaand that the “Adiantum type,” at least in the Schizaeaceae, is derived. This suggestion is discussed in relation to other possible interpretations.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1971.tb09980.x

出版商:Wiley    

年代:1971

数据来源: WILEY

摘要:

The original material ofQuercus undulataTorr. was collected by Edwin James on Major Long's expedition to the Rockies in 1820. The type locality was stated by Torrey as “sources of the Canadian and the Rocky Mountains.” Evidence is here adduced that the type locality is on Ute Creek, a tributary of the Canadian River, in northeastern New Mexico. The site was found to harborQ, gambelii, Q. grisea, and numerous intermediate hybrid forms. Certain of the latter match the type ofQ. undulataquite closely. The type sheet includes three elements—a branchlet regarded as the type, a twig ofQ. grisea, and an isolated acorn ofQ. havardii. Torrey's new species was illustrated by a figure which does not closely resemble the type, but which is more similar toQ. havardii. The acorn ofQ. havardiion the type sheet must have been collected in the Texas Panhandle or western Oklahoma, where Long's party would have encountered this species. In my opinion, Torrey's figure could have been drawn from a specimen collected there, which, except for the isolated acorn, has since been lost.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1971.tb09981.x

出版商:Wiley    

年代:1971

数据来源: WILEY

摘要:

A systematic study of leaf morphology and anatomy of native, aquaticPolygonum, species is presented, treating 60 populations propagated in a common greenhouse. On the basis of this study it is now possible to distinguish AmericanPolygonumspecies by leaf characters alone. Taxa in section Persicaria are contrasted and also compared with representatives of sections Bistorta and Echinocaulon. A complete description, utilizing 40 leaf characters, is given for each taxon. Complex glands, designated valvate chambers, are shown to be a consistent feature of theP. punctatumspecies‐complex, whereas epidermal storage‐idioblasts are present only in certain populations of this group. All other species lack valvate chambers but possess idioblasts, which may reach a frequency of over 400/mm2in'P.hirsutum. The plate‐like multicellular gland ofP. opelousanumis found to occur sporadically inP. hydropiperoides, thereby losing its specific diagnostic value. Illucidation of the characteristic structure of this gland, however, lends evidence to discourage the theory that it is an abortive structure produced by a hybrid between glandular and non‐glandular species. Reticulate venation and unicellular trichomes separate members of section Bistorta from the smartweeds, butP. meisnerianum(section Echinocaulon) is shown to simulate leaf structure of the persicarias both internally and externally.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1971.tb09982.x

出版商:Wiley    

年代:1971

数据来源: WILEY