摘要:

Mitotic chromosome counts are reported for 12 species ofOedogoniumwith the following distribution: two species with 13 chromosomes, two species with 16 chromosomes, five species with 17 chromosomes one species with 19 chromosomes, one species with 32 chromosomes, and one species with 38 + 1 chromosomes. Diploid strains of two species are illustrated and discussed. Cytological comparison of species establishes that there is great diversity inOedogoniumwith relation to chromosome number, size, and morphology.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb06920.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

Cyamopsis tetragonoloba, guar, produces two leaf forms: a simple leaf and a trifoliate leaf. The steps in the development of each of these forms have been investigated in an attempt to determine the precise point at which the leaf primordium becomes destined to produce one or the other characteristic leaf shapes. Up to 140 μ in length the leaf primordia are morphologically indistinguishable. If a simple leaf is to be formed the marginal meristem remains continuous and initiates only lamina. If a trifoliate leaf is to be formed the continuity of the marginal meristem is interrupted by a group of “pocketal” cells dividing it into an upper lamina meristem and a basal leaflet buttress.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb06921.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

Cyamopsis tetragonoloba, commonly called guar, produces two leaf forms: a simple leaf and a trifoliate leaf. During ontogeny, the simple leaf is always produced prior to the appearance of any trifoliate forms. The number of simple leaves initiated during the early phase of ontogeny is partially controlled by environmental conditions. Both short daylengths and high temperatures delay the production of the trifoliate form. Treatments using gibberellic acid and reduced light intensity favor production of simple leaves. Removing the cotyledons of young seedlings also favors the simple leaf form. Some consider a change in leaf form as an indication of a change from the juvenile phase to the adult phase of growth. However, in guar when the capability to reproduce is used as the basis for the determination of phase change, a change in leaf form is a separate phenomenon.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb06922.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

The roles of tryptophan, kynurenne, 3‐hydroxyanthranilic acid, and quinolinic acid as niacin precursors were investigated by assessing their germination and growth‐promoting effects in orchid embryo and seedling cultures. Only niacin, 3‐hydroxyanthranilic acid, quinolinic acid and kynurenine exhibited a growth‐promoting effect on seedlings of all ages. Tryptophan inhibited the growth of 70‐day‐old seedlings but enhanced growth of older seedlings. The data presented are interpreted to be consistent with the hypothesis that orchids may synthesize their niacin by a pathway similar to that of certain bacteria, fungi, birds, and mammals.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb06923.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

The discovery of specimens ofCalamostachys binneyanain Lower Pennsylvanan petrifaction material in North America has provided additional information about the structure of this calamitean fructification. The cones consist of regularly spaced alternating whorls of bracts and sporangiophores. Bracts are fused in a disc except at the margin where the individual units become free. Sporangiophores are inserted at right angles to the cone axis and bear four axially directed sporangia. The vascular system of the North American specimens differs from that in other reports of the taxon in the presence of twelve vascular bundles in the cone axis. Each sporangiophore is supplied by a single vascular trace that departs from one axial bundle. There appears to be no constant relationship between the number of vascular bundles and the number of bracts. Spores are spherical, thin‐walled, and of theCalamosporatype. Relationships with other structurally preserved members in the genus are discussed in light of the diversity in structure demonstrated by the new specimens.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb06924.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

Despite the potential contribution suggested from chromatographic studies of many groups, taxonomic conclusions based on paper chromatography alone may carry some inherent errors. In many instances chemical differences between taxa cannot be characterized by two‐dimensional chromatography of crude extracts. Pigment diversity may go unnoticed in such a study, and conclusions based on simple chromatographic results may show too much similarity between the taxa being compared. The resolution of chromatographic separations of the often very complex mixtures encountered in crude plant extracts can be greatly improved by a preliminary column separation, and in this study a method of pigment analysis employing both preliminary column and subsequent paper chromatography is used. While it is usually impractical to identify all of the components of a flavonoid complex, each member should be characterized to the degree that it can be distinguished from all others. Here, the characterization of a component includes its rate of movement in the column, relative position and color under ultraviolet light on the chromatogram, the absorption spectrum in ethanol and the change in the absorption spectrum when a reagent is added to the ethanol which has a particular effect on the spectral properties of that flavonoid. With very few exceptions no one criterion of characterization is definitive for any component. More than 20 flavonoid pigments have been observed in the two tetraploidGossypiumspecies,G. barbadenseandG. hirsutum.Only 10 of the constituents were common to the two species. The results of a previous study based on two‐way paper chromatography of crude extracts makes the two species appear much more similar in flavonoid composition than is indicated by the more detailed column‐paper chromatography presented here. The degree of difference betweenG. hirsutumandG. barbadenseis surprisingly large in light of the generally accepted theory of their common origin. The value of chromatographic‐chemotaxonomic studies is greatly increased if the chemical systems involved are characterized.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb06925.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

New specimens ofSpencerites mooreiadd knowledge of its sporophylls and method of sporangial attachment. The sporophyll consists of a slender pedicel which expands at its distal end into a fleshy, peltate, diamond‐shaped head which bears a presumably fleshy lamina. The sporangium is attached through most of its length to the adaxial surface of the pedicel rather than distally as inS. insignis.It is suggested that the distal attachment shown inS. insignismay be derived through a phyletic shift from the pedicellate position. Additional specimens ofSpenceritesprovisionally assigned toS. majusculusare also recorded. The spores are bilateral, monolete, and shaped like quadrants of a sphere. Two prominent wings extend along the two contact faces and the monolete mark is prominently raised, thus imparting a three‐winged appearance to the spore. The axis consists of an exarch protostele and a cylinder of thick‐walled outer cortex.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb06926.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

The karyotypes of 32Phloxtaxa were studied in many plants representative of populations found throughout eastern North America. Most plants were diploid with 2n= 14, but a few tetraploids and plants with B‐chromosomes were also observed. Some species were virtually indistinguishable karyotypically, while others differed. Within and between the SubsectionsSpeciosae, Divaricatae, andSubulatae, strikingly similar karyotypes were observed. Other Subsections differed significantly, with theOvataeshowing strong intrasubsectional variation. Increased karyotype asymmetry is correlated with morphological specialization. Where polyploidy was observed, discordant chromosome sets indicated allopolyploidy.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb06927.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

Microscopic observation of cells ofPicea glauca, grown in tissue culture under a variety of cultural conditions, reveals a series of phenomena which are believed to be associated with the development of specific types of cells recognizable in intact plants. Characteristically patterned deposits of resin drops, and strands, furrows, and channels in the cytoplasm appear to be capable of serving as templates around which cellulose and lignin may later be deposited. The cytoplasm is extruded into characteristic papillae, and cell content may be extruded slowly or ejected with force through the cell walls, through multiple pores of characteristic distribution. Material ejected from such cells condenses in characteristic extracellular patterns. All of these processes may contribute to the differentiation of recognizable distinct cell types.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb06928.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

A new species ofDictyostelium, isolated from a decaying ear of corn in Hawaii, is described. Because of the numerous irregularities in its developmental morphology and general appearance, it is being namedD. irregularis.Aggregation is by amoebal streaming, and the aggregation mass commonly segments into several pseudoplasmodia, each of which produces a sorocarp in situ or after migration. During migration stalk material is laid down behind the pseudoplasmodium. The mature sorocarps, which do not exceed 1 mm in height, have very irregular stalks and globular‐to‐elongate sori with elliptical spores that measure 3.5‐7 × 4.8‐9.8μ. Cyst formation was not observed. The new species is of particular interest from the standpoint of its probable primitive position in the genus.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb06929.x

出版商:Wiley    

年代:1967

数据来源: WILEY