摘要:

Chromic acid, iodine‐potassium iodide and Dragendorff reagent were employed to identify reactive cells that may indicate sites of alkaloid accumulation in fresh tissues and latex ofC. roseus.Laticifers in all parts of the mature plant and certain parenchyma cells in the cortex and pith regions accumulated reaction products of these alkaloid indicators. These same cells showed primary fluorescence, accumulated vital dyes and lipid indicators in excess of other cells, and exhibited a more intense nadi reaction than other cells. Tests on fresh tissues are interpreted to indicate possible qualitative and quantitative differences in alkaloid content between subterranean and aerial portions of the plant and between mature and immature tissues. These studies showed that reactive products are unevenly distributed in cells and organs of the plant and can be microscopically detected only in laticifers and specialized parenchyma cells.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb13202.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Both intact and cut duckweed plants were prepared for electron microscopy. Plants which are prepared intact do not exhibit callose formation during development of sieve‐plate pores. Future pore sites can be recognized by the presence of median cavities that are unassociated with callose platelets. These cavities are first seen in the region of the compound middle lamella and are lined by a plasmalemma. As end walls thicken, the cavities increase in size until open pores of uniform width are formed. Mature sieve plates of intact‐prepared plants are also devoid of callose. Fully opened pores are lined by a plasmalemma and are only traversed by an occasional tubule of endoplasmic reticulum. Plants which have been cut prior to fixation possess mature sieve plates containing callose. The pores of developing sieve plates in cut plants exhibit small amounts of callose. Except for the lack of callose, lateral wall connections between sieve elements and contiguous cells are similar in development and mature state to those reported for other species.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb13203.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

The development and/or modification of special acid etching and macerating techniques permits pyritized fossils ofLeclercqia complexato be separated into their carbonaceous wall remains and pyrite lumen—pit casts. These carbonized and pyritic portions can then be studied separately by both light and SEM microscopy and information from both modes compared with that obtainable from carbonaceous compression fossils ofL. complexa.This combination of techniques, preservation modes and methods of analysis, allows a synthesis of information obtainable from each, as well as providing a check on errors of interpretation due to preservation mode and method of observation. The developmental sequence of the secondary wall thickenings of the protoxylem elements is shown to be annular to connected annular and spiral, with both exarch and mesarch maturation. The metaxylem shows a transition through reticulate to multiseriate round, oval, and elongate bordered‐pitted tracheids. Different wall facets of separated pyrite tracheid casts can be examined by the SEM and variations in wall structure and pitting characterized. Cells of the outer cortex are 6 to 10 times longer than wide, have thickened vertical walls and end walls that vary from nearly horizontal to angles of overlap of 50 degrees.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb13204.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

An anthecological study ofTiliain the Great Plains and New England was undertaken for both native and introduced species. The floral bracts are postulated as being at least as important in pollinator attraction as they are in fruit dispersal. A characteristic sweet odor is always present, but becomes stronger at dusk. Flowers are protandrous with anthers opening for the first time late in the afternoon and releasing pollen abundantly for about 24 hr. Initial nectar production coincides with stigma receptivity which begins late in the afternoon, but on the second day a flower is open. Sixty‐six species of insects in 29 families were collected. Bees and flies are the most common diurnal visitors and moths are the primary nocturnal visitors. Samples of pollen taken from the insects indicate a relatively high constancy. Experimental tests show thatTiliais not apomictic or self compatible. Anemophily plays a secondary role to entomophily in pollination. Nocturnal pollinators are slighly less effective than diurnal pollinators in effecting fruit set. Although nocturnal pollinators are favored by the syndrome of floral characteristics, it is concluded thatTiliais a generalist in regard to pollination. It is proposed that the lack of clear morphological differences betweenTiliaspecies leads to pollinator inconstancy and thus hybridization.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb13205.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Tissue culture cells ofStreptanthus tortuosusvar.orbiculatus(Cruciferae) which have acquired a spherical viruslike particle located in their nucleoli, designated cell line STV, developed supergranal chloroplasts and lost the ability to differentiate vascular tissues. The effect of temperature on the ultrastructural cytology of one line of the STV tissue, STV‐I, was compared with the effect of temperature on the ultrastructural cytology of tissue culture cells lacking the viruslike particles (control cell lines). At 4 C, the cellular and ultrastructural appearance of control tissue culture cells differed from that of tissue grown at 22 C by producing increased amounts of endoplasmic reticulum and dictyosomes and by reduction of chloroplast thylakoids. STV‐I cells were generally moribund as a result of 4 C treatment. Chloroplast thylakoids were also reduced in control tissue following growth at 10 C and the apparent quantities of endoplasmic reticulum and dictyosomes were similar to those observed in control cells grown at the control temperature (22 C), but less than those observed in tissue subjected to 4 C. STV‐I tissue grown at 10 C demonstrated increased endoplasmic reticulum and dictyosomes and reduction of polysomal configurations. The mitochondrial morphology was variable and the cells contained supergranal chloroplasts and proplastids. At the control temperature (22 C), the fine structural appearance of control tissue culture cells was typical of parenchyma cells, but STV‐I cells contained mitochondria of variable morphology and two types of chloroplasts— normal and supergranal. Control tissue grown at 30 C also contained proplastids, but these proplastids contained starch in contrast to the proplastids in control tissue grown at low temperatures. The ultrastructural cytology of STV‐I cells grown at elevated temperature (30 C) was characterized by enlarged mitochondria containing massive lipid bodies and the presence of protoplastids with starch and supergranal chloroplasts.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb13206.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Complementary freeze‐fracture replicas and high resolution tantalum‐tungsten shadowing have been used in a study of the membanes of the marine algaChrysochromulina chiton.Membrane particle populations range from 38/100 nm2in the plastid to 2/100 nm2in the pyrenoid cap membrane. Membrane asymmetry was evident in all membranes, but was most obvious in those with higher particle numbers. In all complementary replica pairs, particles were always more numerous on protoplasmic fracture faces. Small, particle‐free areas with bordering particles were also seen as recurring membrane features. Complementarity of matching fracture faces was seen for very small background granularity patterns and for large membrane components, but not for particles. Complementarity can also be seen in non‐membranous fracture faces both within and external to the cell, suggesting the presence of polymeric materials in these areas that produce “particles” due to plastic deformation.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb13207.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

The adult leaf ofCarludovica palmataconsists of a plicate lamina, adaxial hastula, petiole, and sheath. The leaf is unusual in the angiosperms because about two‐thirds of the apical meristem is utilized in its initiation. The adult leaf requires about 4–5 plastochrons to mature. Shortly after its initiation the adult leaf and apical meristem collectively appear pyramid‐shaped and various parts of the mature adult leaf may be traced back to particular portions of the pyramid. Plications develop by differential growth within the lamina, not by splitting of leaf tissue. Quantitative studies indicate that certain regions of the developing adult leaf elongate more rapidly or slowly than other regions depending upon the stage of leaf development. The adult leaf ofC. palmatadevelops differently from those of previously studied palms in various ways. It therefore appears less justifiable to consider the superficial similarity between the adult leaves of various Cyclanthaceae (particularly those ofCarludovicasensu strictu) and those of fan palms as evidence of especial affinity between the Cyclanthaceae and Palmae. Juvenile leaves of C.palmatadiffer from adult leaves both in their mode of origin and appearance at maturity. The juvenile leaf appears homologous to the entire adult leaf.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb13208.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Structurally preserved arborescent lycopsid fructifications are described from Pennsylvanian age strata in eastern Kentucky and southern Illinois.Achlamydocarpon variuscomb. nov. is the name proposed for these cones and previously reported isolated megasporophylls described asLepidostrobophyllum varius.The specimens range up to 3.5 cm long and represent cone apices. Megasporophylls are spirally arranged and attached to the cone axis at an acute angle. Megasporangia are large with a wall two cell layers thick. Each sporangium contains one large, presumably functional megaspore, and three smaller, abortive megaspores. Functional and abortive spores possess a prominent apical tuft (massa) that covers up to one‐third of the proximal surface of the spore. Sporoderm ultrastructure is detailed together with a comparison of morphologically similarsporae dispersaemegaspores. The possible function of the megaspore massa is discussed as it relates to the reproductive biology of the cone.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb13209.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

The anatomical development of trichilia and Müllerian bodies ofCecropia peltatawas investigated at the light microscope level. The petiole base is initiated in a normal manner and the abaxial surface becomes keel‐shaped during later stages of development. At maturity the trichilium is well supplied with vascular tissue but no transfer cells were observed. Before Müllerian body development, trichilium epidermal cells become modified into two types of trichomes. Müllerian bodies are initiated in sub‐epidermal tissue and by continued cell division and expansion reach a size of 1 mm wide X 3 mm in length. There is no storage polysaccharide present during early stages of Müllerian body development. Glycogen production and storage begins as the food body reaches three‐fourths final size and continues after cell division ceases. The mature Müllerian body is mutlicellular and rich in lipid and glycogen.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb13210.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

The developmental ultrastructure of the glycogen plastids produced in Müllerian body cells ofCecropia peltatawas studied. Cells of the trichilium, before Müllerian body initiation, possess chloroplasts. Once cell division begins in the initiation of a food body, the choroplasts dedifferentiate to proplastids. As cell division and development proceed the proplastids divide and enlarge so that each cell of the Müllerian body contains 20–30 of these organelles. With maturation of a Müllerian body the proplastids begin to synthesize and store glycogen. Each developing glycogen plastid possesses an inclusion composed of protein and glycogen, and, based on cytochemical evidence, it is suggested that the glycogen synthesizing enzymes are associated with this inclusion.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb13211.x

出版商:Wiley    

年代:1976

数据来源: WILEY