摘要:

Whisler, HowardC. (McGill U., Montreal, Canada.)Culture and nutrition of Amoebidium parasiticum.Amer. Jour. Bot. 49(3): 193–199. Illus. 1962.—The little known Trichomycete,Amoebidium parasiticum, has been isolated into pure culture Maximum growth was obtained on a thiamine‐enriched Tryptone‐glucose medium. Growth also occurred on a defined medium consisting of thiamine, glucose, methionine, ammonium and inorganic salts. Methionine could not be replaced by sulfate orl‐cystine. Both mannose and fructose could satisfy the carbon requirement. At present, reproduction in pure culture is always by sporangiospores, but the amoeboid phase can be induced by the addition of crushed host material.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14929.x

出版商:Wiley    

年代:1962

数据来源: WILEY

摘要:

Stone, DonaldE. (Tulane U., New Orleans, Louisiana.)Affinities of a Mexican endemic, Carya palmeri, with American and Asian hickories.Amer. Jour. Bot. 49(3): 199–212. Illus. 1962.—Morphological studies of the leaf margins, stomata, trichomes, and fruits provide persuasive evidence for recognizingCarya tonkinensisandC. cathayensis(southeastern Asia) as vicarious relatives ofC. palmeri(Mexico). Also,C. cordiformis(U. S. and Canada) shares features of the axillary bud prophyll and secondary nut partition that make this quartet of species unique in the Section Apocarya. It is suggested that these species display some of the primitive characters of the genus. and that they may be ancestral stocks. Discussion is centered around their ecogeographic discontinuity and its bearing on the preponderance of hickory species in eastern U. S.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14930.x

出版商:Wiley    

年代:1962

数据来源: WILEY

摘要:

Reinert, Grady, W., and R. K. Godfrey. (Florida State U., Tallahassee.)Reappraisal of Utricularia inflata and U. radiata (Lentibulariaceae).Amer. Jour. Bot. 49(3): 213–220. Illus. 1962.—Utricularia inflataandU. radiata, interpreted either as separate species or 2 varieties of a single species by previous investigators, are shown to be specifically distinct on the basis of 5 hitherto‐neglected, morphological characters, 4 of which are vegetative in nature, and on the basis of 3 reinvestigated quantitative criteria. The particular attention devoted to the vegetative bodies of the 2 plants led to the discovery, inU. inflata, of tuber formation, a phenomenon known to occur in Utricularias in general but unreported for North American species. Support for interpretingU. inflataandU. radiataas species resides in the distribution patterns. Although both occur on the outer coastal plain from southern Alabama to southern Delaware, the 2 taxa are easily distinguishable and exhibit no intergradation. The range ofU. radiatais much broader; it extends westward to eastern Texas northeastward to Nova Scotia, and is disjunct inland in western Tennessee, western Virginia and in northwestern Indiana.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14931.x

出版商:Wiley    

年代:1962

数据来源: WILEY

摘要:

Wilcox, Hugh. (State U. Coll. of Forestry, Syracuse, New York.)Growth studies of the root of incense cedar, Libocedrus decurrens. I. The origin and development of primary tissues.Amer. Jour. Bot. 49(3): 221–236. Illus. 1962.—The anatomical features of active and dormant roots of incense‐cedar seedlings are described and discussed in relation to various problems of differentiation and morphogenesis. Autoradiographs confirm the presence of a group of relatively inactive cells at the site of the apical initials. During periods of maximum growth activity, the presence of a quiescent center is accentuated by a peak in number of divisions in adjacent tissues. With diminution in growth activity, the peak occurs closer to the quiescent center and the size of the meristem appears to diminish. During dormancy, the configuration of the initial region seems to indicate the existence of apical initial cells which coincide with a minimal constructional center, as determined by studies of cell lineage. Roots whose apical cells retain their meristematic appearance are able to resume growth after a period of dormancy, whereas roots whose apical cells undergo vacuolation are likely to perish. Graphs are presented to show the functional relationships between growth rate and the varying distances from the apical meristem at which the tissues of the root differentiate and mature. Although early differentiation of precursory phloem could be discerned almost as soon as early vacuolation of metaxylem, its recognition was more dependent upon subjective judgment. The functional relationship between differentiation and growth rate was most pronounced in the maturation of protoxylem elements, the development of Casparian strips in the endodermis, the development of suberin lamellae in the endodermis, and by the development of phi layers in the inner cortex.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14932.x

出版商:Wiley    

年代:1962

数据来源: WILEY

摘要:

Wilcox, Hugh. (State U. Coll. of Forestry, Syracuse, New York.)Growth studies of the root of incense cedar, Libocedrus decurrens. II. Morphological features of the root system and growth behavior.Amer. Jour. Bot. 49(3): 237–245. Illus. 1962.—The common pattern of root growth in incense cedar involves a rush of growth in the spring, a midsummer low, and a renewed surge in the fall. Not all of the roots of a seedling grow at any one time, but some roots are growing while others are dormant. The cycle of growth of an individual root varies from 3 to 9 weeks or more; the large‐diameter roots and the principal laterals grow more rapidly and for longer periods than the smaller‐diameter roots or those of higher order. Roots of various growth rates were treated with different concentrations of indoleacetic acid and with extracts from growing and dormant roots. Roots show adaptation to the lower concentrations of IAA, with subsequent stimulation of elongation occurring in solutions of concentrations 10‐6through 10‐9moles/liter of IAA. Roots which have been growing slowly at the time of treatment are more strongly stimulated than those which have been growing rapidly. Roots do not become adapted to root extracts but remain inhibited by all such treatments. A study of the anatomical features of dormant and actively growing roots provides indirect evidence that a number of hormonal factors are operating to control the various physiological activities associated with the growth of the root.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14933.x

出版商:Wiley    

年代:1962

数据来源: WILEY

摘要:

Wheeler, GeorgeE. (Brooklyn Coll., Brooklyn, N. Y.)Polygonal aspects of cell faces. I. Pentagons and hexagons as prevailing types.Amer. Jour. Bot. 49(3): 246–252. Illus. 1962.—Different types of cell faces, classified as to polygon type (i.e., number of sides per face), may predominate in different samples of internal cells and of internal tissues; no single face type is exclusively predominant in all tissues. Pentagons usually are the most numerous type in the cell samples reported in the literature, but hexagons exceed them in some samples. Generally, these 2 “compete” for numerical supremacy. Perpetuation of an already‐established, face‐type dominance was studied, using data from the literature and from original diagrams. Cell‐division orientation, i.e., the location and the relative positioning of new cell‐division walls, was found to be the prime factor in maintaining the preponderant type. The polygon nature of the new wall is an additional, but less important, factor. Typical division events tend to favor pentagonal faces; but with an increase in cell division “regularity,” hexagons begin to rise in numbers. During the early stages in tissue differentiation, while mitosis is still occurring, one face type may replace another as the predominating type. Such a shift may be associated with the developmental characteristics of that tissue.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14934.x

出版商:Wiley    

年代:1962

数据来源: WILEY

摘要:

Johnson, B. Lennart. (U. California, Los Angeles.)Amphiploidy and introgression in Stipa.Amer. Jour. Bot. 49(3): 253–262. Illus. 1962.—Frequent specimens heretofore referred toStipa californica(2n= 36) were found to be similar to an undescribed polyploid (2n= 68) species ofStipaon the ratio of lemma to palea length. On other individual diagnostic characters,S. californicaand the polyploid were not separable. However, on the discriminant function (Z) comprising 5 such attributes, their mean difference was highly significant. The polyploid is given the new species name,Stipanevadensis. Appropriate tests using the function Z excludedS. californicaas a possible parent of the polyploid and pointed toS. lettermani(2n= 32) and the combined speciesS. occidentalis(2n= 36) andS. elmeri(2n= 36) as the putative parents. The last 2 species were barely separable on multigenic differences measured by the discriminant function, and the mean Z forS. californicafell near the mid point between them andS. columbiana(2n= 36). This fact together with evidence from the frequency distribution of Z suggested a hybrid origin forS. californicaand introgression with its putative parents.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14935.x

出版商:Wiley    

年代:1962

数据来源: WILEY

摘要:

Turner, B. L.. and R. M. King. (U. Texas, Austin.)A cytotaxonomic survey of Melampodium (Compositae‐Heliantheae).Amer. Jour. Bot. 49(3): 233–26. Illus. 1962.—Chromosome counts are reported for individuals from 89 populations ofMelampodiumrepresenting 26 species The genus is multibasic withx =9, 10, 11, 12, 16 and 23. Chromosome numbers on a base ofx= 10 characterize the section Melampodium while basic numbers ofx= 23, 16, 12, 11 and 9 occur in the section Zarabellia.Melampodium camphoratum(n= 16) differs from all other species examined in having relatively small meiotic chromosomes. Only 6 of the 23 species are polyploid or have polyploid races.Melampodium leucanthumandM. cinereumhave both diploid and tetraploid populations; the latter occur without any apparent morphological or geographical correlation and are probably autoploid in origin. A survey of the basic chromosome numbers known for other genera of the subtribe Melampodinae (12 of 22 genera) is presented. and it is suggested thatx= 10 is the most probable basic number of the genus and subtribe.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14936.x

出版商:Wiley    

年代:1962

数据来源: WILEY

摘要:

Schwinghamer, E. A. (Brookhaven Natl. Lab., Upton, New York.)Studies on induced variation in the rhizobia. III. Host range modification of Rhizobium trifolii by spontaneous and radiation‐induced mutation.Amer. Jour. Bot. 49(3): 269–277. Illus. 1962.—Mutant strains capable of nodulating pea seedings ineffectively (incapable of nitrogen fixation) have been obtained from 2 antibiotic‐resistant marked strains ofRhizobium trifoliiwhich normally do not form nodules on this host. Such variant forms apparently occur spontaneously in these strains at a low frequency which can be significantly increased by irradiation with ultraviolet light, X rays, and fast neutrons. Nodulation of vetch, sweet peas and several varieties of peas by the mutant strains suggests a close parallelism of the extended host range with the range ofR. leguminosarum, although nitrogen fixation by the mutants on the new hosts is negligible or absent. The mutant nodules on these hosts also differ from those of the pea strains in slightly smaller size, spherical form, and lighter pink color. Nodule morphology on the homologous host, clover. appears unaltered but a slight loss of effectiveness was noted on red clover. This loss may be attributed partly to a reduction in infective ability since the average number of nodules formed per plant of clover or pea is appreciably lower than for comparable inoculation by strains of nonmutantR. trifoliiorR. leguminosarum, respectively. Cultural characteristics of mutant strains resemble those of the nonmutantR. trifoliistrains.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14937.x

出版商:Wiley    

年代:1962

数据来源: WILEY

摘要:

Ahmadjian, V. (Clark U., Worcester, Mass.)Investigations on lichen synthesis.Amer. Jour. Bot. 49(3): 277–283. Illus. 1962.—Separated fungal and algal components of the lichen,Acarospora fuscata(Nyl.) Am., were recombined under controlled laboratory conditions to form structures comparable to those of the naturally occurring lichen thallus. The primary condition for this artificial synthesis was the absence of organic and inorganic supplements to the agar substrate. Thus, in effect, the mycobiont was forced into union with the phycobiont. It was demonstrated that both alga and fungus derived benefit from the lichenized association.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14938.x

出版商:Wiley    

年代:1962

数据来源: WILEY