摘要:

Spherical, membrane‐bound inclusions occur in the proplastids and vacuoles of cells ofBryophyllumandKalanchoëshoot apices. Evidence is presented indicating that the inclusions arise by the accumulation of material within the cisternae of certain tubular proplastid membranes and are then transferred to vacuoles. The results obtained from electron microscopy and from histochemical studies indicate that the contents of the inclusions are predominantly lipid.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07376.x

出版商:Wiley    

年代:1968

数据来源: WILEY

摘要:

The anatomy, morphology and gross histochemistry of the germinating embryo and seedling ofPaulownia tomentosa(Scrophulariaceae) is described. Cytohistological changes in the shoot apex are correlated with anatomical and histochemical differences. During the first days of germination and before leaf primordia are formed, there is a gradual increase in staining for cytoplasmic protein and RNA. Once the first leaves are initiated, the staining for these compounds remains constant in the central mother‐cell zone, and further increase in protein and RNA is confined to the developing leaf primordia. Starch grains are found in all areas of the very young apex, but with anatomical maturity the grains are restricted to the central mother‐cell zone. Some electron micrographs point up special cytological features.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07377.x

出版商:Wiley    

年代:1968

数据来源: WILEY

摘要:

The electron microscope was used to examine changes which take place in wall, as well as in internal, structure during germination of mature resistant sporangia ofAllomyces neo‐moniliformis. When the resistant sporangia are first placed in water to initiate germination, nuclei, mitochondria, and endoplasmic reticulum are not evident, though after the sporangia have been in water for more than 30 min all of these structures become visible. At this time no cracks are evident in the resistant sporangial wall and the cell membrane appears highly convoluted. Within the next 30 min the outer wall splits and the inner wall expands considerably as the protoplast increases in volume. At the same time the cell membrane straightens out, apparently in response to the protoplasmic expansion. The “cementing substances” begin to dissolve about this time so that 1 1/2 hr after placement in water the outer wall is completely separated from the inner wall which now acts as the cell wall. Cleavage appears to be initiated by the invagination of the cell membrane and by the appearance of segments of endoplasmic reticulum with filled vesicles at one end. Between 2 1/2 and 3 hr after placement in water zoospores are released.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07378.x

出版商:Wiley    

年代:1968

数据来源: WILEY

摘要:

Contrary to earlier reports, well‐organized but fewer stomata develop on the lower surface of the leaves ofNelumbo nuciferaWilld. during aerial growth. The stomata, however, become obliterated by the readjustment of neighboring epidermal cells. During initial stages of degeneration the guard cells show irregularly thickened walls, disintegrated nuclei, and highly vacuolated cytoplasm. Such abnormal features finally lead to the disappearance of stomata from the lower surface of leaves. The ontogeny, structure and distribution of stomata on leaves, perianth lobes, stamens, receptacles and carpels are described. The stomata are haplocheilic in development and are anomocytic (ranunculaceous) at maturity. The concept of a meristemoid and the significance of this study in taxonomy and phylogeny are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07379.x

出版商:Wiley    

年代:1968

数据来源: WILEY

摘要:

Small pith explants from the fifth internode ofColeus blumeiwere placed on a defined medium supplemented with different concentrations of indoleacetic acid (IAA). With all levels of IAA tissue growth was slight; however, when the medium contained more than 10‐7mIAA, xylem elements developed after 11‐14 days. Omission of sucrose from the medium prevented this differentiation of xylem elements. Isolated xylem cells or small nodules were most common, but long strands were also seen. The merits of theColeussystem for study of plant‐cell differentiation are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07380.x

出版商:Wiley    

年代:1968

数据来源: WILEY

摘要:

Structurally preserved arborescent lycopsid fructifications are described from the Fayetteville Shale (Upper Mississippian) of northwestern Arkansas. Specimens ofLepidostrobus fayettevillensesp. n. range from complete cones 22.5 cm long and approximately 1.0 cm in diameter to smaller water‐worn fragments. The cones consist of a central axis bearing closely spaced, spirally arranged sporophylls which extend from the cone axis at right angles. Each sporophyll consists of a pedicel which is turned up at its end to form a distal lamina. Sporangia are large and attached to the adaxial surface of each sporophyll. The vascular cylinder consists of a centrally located exarch protostele at least 1.1 mm in diameter. The new species is compared with morphologically similar lycopsid fructifications of equivalent age.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07381.x

出版商:Wiley    

年代:1968

数据来源: WILEY

摘要:

C‐phycocyanin has been prepared from algae representative of various orders and families in the Cyanophyceae and Rhodophyceae. The chromophore phycocyanobilin has been cleaved, purified and crystallized as the dimethyl ester. Each sample was compared with reference phycocyanobilin dimethyl ester and found to be identical on the basis of absorption spectral (ultraviolet, visible and infrared) and chromatographic properties. The phylogenetic implications of these results are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07382.x

出版商:Wiley    

年代:1968

数据来源: WILEY

摘要:

The distribution of fifteen sesquiterpene lactones in sixty‐two populations ofAmbrosia psilostachyaranging from Canada to Mexico, and cytological observations for seven populations are reported. Chemical data for four Mexican populations of A.cumanensisKunth are presented. The origin of chemically unique populations ofA. psilostachyawhich occur on the islands and peninsulas that line the Texas Gulf coast are discussed with respect to the chemical, morphological and cytological data.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07383.x

出版商:Wiley    

年代:1968

数据来源: WILEY

摘要:

Chromosome numbers and other karyological features ofArceuthobiumare reported for all species and subspecific groups in the United States and 7 of the 13 entities occurring in Mexico. The only chromosome number known in the genus isn=14 and the karyotype appears to be fundamentally symmetrical. The bivalents are significantly smaller than in the related genusPhoradendron. No supernumerary chromosomes, sometimes present inPhoradendron, were observed inArceuthobium. The existence of strong isolating mechanisms, which apparently preclude natural hybridization, is advanced as a possible explanation for the absence of polyploidy in the dwarf mistletoes. The flowering characteristics of the American species are analyzed and classified into three principal groups: (1) winter and early spring flowering species with southern distributions, (2) summer flowering species with more northerly distributions, and (3) spring flowering species with the highest latitudinal distributions, but which essentially complete floral development during the previous summer. A fourth group is intermediate between the first and second categories.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07384.x

出版商:Wiley    

年代:1968

数据来源: WILEY

摘要:

Ten species ofDicentrawere examined by two‐dimensional descending paper chromatography. The flavonoid components, including anthocyanins, formed patterns which were specific to a species or a group of closely related species, and these confirmed certain natural relationships within the genus. Some of the components were hydrolyzed and close structural relationships among them were revealed. They were further characterized by spray reactions andRFmeasurements in a variety of solvent systems. The inheritance of the components, especially of the anthocyanins, was studied in the hybrids. All parental substances appeared in some hybrids, but in others some parental components were missing. “Hybrid substances” which had not been present in either parent were found in certain hybrids. This is thought to represent either reconstruction of ancestral biosynthetic pathways, probably through genic complementation, or extension of existing synthetic routes through some type of interaction between parental genomes.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1968.tb07385.x

出版商:Wiley    

年代:1968

数据来源: WILEY