摘要:

A comparative study of the leaves of 31 species ofLycopodiumwas made. The pattern of tracheids varies with the species. Usually they exhibit annular, helical, reticulate, modified or transition forms; none of the species have advanced phylogenetically beyond the scalariform tracheid stage. Mucilage canals have been found in four species. Tracheids are enclosed by a few to several layers of oblique ended, elongated parenchyma cells in most species, but an endodermis is absent. Vascular bundles are encircled by fiber cells in three species. The mesophyll of most species consists of identically shaped cells, although palisade‐like tissue has been observed in a few species. The epidermal cells vary from elongated to isodiametric and have either undulated or smooth anticlinal walls, which are deeply pitted in some species. The outer epidermal walls are usually thick and heavily cutinized. Stomates are distributed on both surfaces in 18 species, on the abaxial surface in 11 species, and on the adaxial side in only two species. Most stomates are practically isodiametric in surface view, broader than epidermal cells, usually parallel to the vein, and at the same level as the adjacent epidermal cell. A typical guard cell has a prominent outer ledge and a less developed inner ledge of cutin in most species. Six groupings are suggested, based on similarity of leaf structure and the known chromosome numbers.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12288.x

出版商:Wiley    

年代:1974

数据来源: WILEY

摘要:

The effects of gibberellic acid (GA3) and the growth retardant AMO‐1618 on ovule formation in excised pistils ofNigella sativaL. were studied by sterile culture techniques. Gibberellic acid promoted pistil growth and inhibited ovule formation. The role of endogenous gibberellins in ovule formation and pistil growth was investigated by adding AMO to the basal medium. Both pistil lengths and ovule formation were reduced significantly with increasing concentrations of AMO. The addition of low concentrations of GA3to the medium restored pistil growth but did not reverse the inhibitory effect of AMO on ovule formation. The addition of kinetin or indoleacetic acid (IAA) to the medium containing AMO had no effect on pistil lengths. However, with the addition of 10−7m kinetin, the number of ovules in pistils was increased but not to the levels found in pistils grown in the absence of AMO.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12289.x

出版商:Wiley    

年代:1974

数据来源: WILEY

摘要:

Auxin transport and immobilization were followed in the petioles of intact plants ofColeus blumeiBenth. after application of IAA‐2‐14C at a physiological concentration as droplets to the upper surface near the base of the blades of leaves #3 and #5. After 14 hr transportable and immobilized radiocarbon was found all along the petioles. Moreover, about half the total amount of14C detected within the plant (= uptake) had moved beyond the petioles. This was true for leaves of both ages although the younger #3 petioles were only about half as long as the older #5 petioles. Because the uptake of radiocarbon by the #3 petioles was roughly half that of the #5 petioles, the absolute amounts immobilized per unit length of section were essentially uniform in the two petioles. On the contrary, the fractions remaining transportable within the #3 petiole sections averaged half those of the #5 petiole sections. The distribution of the transportable and the immobilized radioactive fractions along the petioles was characterized by high values near the apical application point, a decrease toward the middle of the petioles, and an increase to the level of the apical part toward the base of the petioles, which includes the abscission layer. The results have been discussed in connection with measurements of the cross sectional areas and the lengths of the epidermal and subepidermal cells along the petioles. An auxin transport and immobilization model, which assumes there are two different immobilization systems of different strength in the differently aged tissues, is outlined to explain the observations.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12290.x

出版商:Wiley    

年代:1974

数据来源: WILEY

摘要:

A basic protein, lysozyme, labeled with fluorescein isothiocyanate, is readily taken up by roots oflasione montana.Most of the protein taken up is tightly bound to cell walls of the roots. Fluorescent protein is diluted in the growing region of a root as cells elongate and divide. Fluorescence remains in mature nongrowing regions and root cap cells for one to two weeks. Redistribution and translocation of the protein within the root is minimal or nil. A layer of chloroform‐soluble material that prevents lysozyme from interacting with stem cell walls exposed to fluorescent lysozyme was found on stems of germinatingIasione montana.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12291.x

出版商:Wiley    

年代:1974

数据来源: WILEY

摘要:

InSpirodela oligorhizaandWolffia punctataultraviolet energy induces the conversion of colorless flavans present in scattered idioblasts to red‐brown phlobaphene‐like compounds. The rare appearance of pigment cells in laboratory grown material is discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12292.x

出版商:Wiley    

年代:1974

数据来源: WILEY

摘要:

The pollen ofBoerlagiodendron, one of the most distinct genera of Araliaceae, is unique within the family in its remarkable degree of differentiation of sexine into pertectate and intectate patterns and in its reduced apertures. The unexpanded mesocolpia and the inconspicuous apertures have apparently caused misinterpretation of the pollen morphology ofB. pectinatumin recent literature. A comparative study of several pollen features, together with the meristic characters of carpels and stamens, has demonstrated some significant correlations among them. It appears that the origin of the genus may have been centered around the New Guinea and Solomons areas.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12293.x

出版商:Wiley    

年代:1974

数据来源: WILEY

摘要:

Time‐lapse photomicrography and autoradiography were used to study the initial events leading to the first cell division following transfer from red to white light. The first responses to white light, an apical swelling and a reduced rate of elongation, were often observed within the first 1–2 hr after the transfer; these two changes were not always initiated at the same time. Only the dome region of the cell participated in the elongation in red, as demonstrated by the displacement of anion exchange resin markers. The dome region as well as the region proximal to the dome was associated with the apical swelling, including regions formed in red. The average duration of the G1, S, G2, and M phases was found to be approximately 4, 3, 3.5, and 1 hr, respectively.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12294.x

出版商:Wiley    

年代:1974

数据来源: WILEY

摘要:

The plasma membrane of cultured cells of several plant species was observed to possess invaginations, or secondary vacuoles, of variable size in the adjacent cytoplasm. These structures, which occurred in cells at different phases in vacuolation, were very numerous in thin sections of some cells but fewer in others. In vacuolated cells enlarged secondary vacuoles protrude into the primary vacuole but are delimited from the tonoplast by an intermembrane zone of variable width. The plasma membrane at the orifice of an invagination may fuse and detach the secondary vacuole from the membrane to form in the cytoplasm a structure bounded by a single membrane. Complex accumulations of membranes consisting of spherical, tubular, and laminar structures, possibly containing cytoplasm, may develop within secondary vacuoles. Contents of many of these vacuoles arise from folds along its limiting membrane which pinch off into the interior of the secondary vacuole. A fibrous substance, possibly derived from the wall, is present in some secondary vacuoles. Observed folding of the plasma membrane and measurements of membrane width of various organelles and cytomembranes support an interpretation that endocytosis occurs in cultured cells.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12295.x

出版商:Wiley    

年代:1974

数据来源: WILEY

摘要:

Clavaria flavescens, C. flava, C. aurea, C. pallida, andC. rubella, species originally described by J. C. Schaeffer and currently placed inRamaria, are reexamined and redescribed in modern terms following studies of original literature and specimens from type localities.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12296.x

出版商:Wiley    

年代:1974

数据来源: WILEY

摘要:

Leaves ofQuercus coccinea, Q. alba, andPinus rigidawere collected at six dates during the growing season and analyzed for N, P, K, Ca, Mg, Fe, S, and Na. Leaf weights per unit of leaf area (or length) were determined for the same period.Quercus coccineaandQ. albaleaves increased in weight per unit area by about 30 % and 50 %, respectively. First‐year pine leaves increased in weight per unit length by about 65 %. During the second year the weight of pine leaves changed little. Two broad patterns in the nutrient content of leaves were apparent when nutrient content was expressed on the basis of leaf area rather than leaf weight. N, P, and K concentrations increased to a peak in mid‐ or late summer and declined abruptly just prior to abscission. Concentrations of other elements tended to rise slowly throughout the life of the leaves in all three species. The differences among nutrients and among species support the hypothesis that differential partitioning of the nutrient pool occurs as a result of evolutionary adaptation. The changes in weight of leaves per unit area and in nutrient content during the growing season are important for studies of net primary production and in appraisals of the cycling of nutrients. Least distortion of nutrient relationships occurs when area or length of leaf is used as the basis for expression of nutrient content.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12297.x

出版商:Wiley    

年代:1974

数据来源: WILEY