摘要:

Kleinodendron, a new genus of Euphorbiaceae, was assigned by Smith and Downs to the tribe Cluytieae. A xylem anatomical survey indicates that there are no objections to this placement. Woods of Cluytieae are diverse but may be characterized generally by having pores which average less than 80μin diameter and which are well divided between solitary and radial multiple distributions in the same species; simple vessel perforations; alternate intervascular pitting; fiber‐tracheids and libriform wood fibers; exclusively uniseriate, or uniseriate and biseriate heterocellular vascular rays in the same species; uniseriate “bridges” linking superposed biseriate ray segments; diffuse, diffuse‐in‐aggregates, and scanty vasicentric axial parenchyma, sometimes in the same species; and crystal rhomboids. ThatMicrodesmisandPogonophoradiverge sharply from these generalizations in having scalariform vessel perforations and broad vascular rays, is an indication that they may not be closely related to other genera in Cluytieae.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10687.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

Chromosome counts are reported for 81 collections of tropical grasses from Suriname, Brazil and the Dominican Republic, these representing 29 genera and 65 species. The records forBulbulus, Guadua, HomolepisandPiresiaare the first for these genera, as are the counts for the 36 following species:Arundinella confinis, Axonopus marginaius, Axonopussp. nov.,Bulbulus nervatus, Digitaria fuscescens, D. neesiana, Echinolaena inflexa, Elyonurus adustus, Eragrostis glomerata, E. maypurensis, E. polytricha, Guadua capitata, Homolepis isocalycia, Ichnanthus nemoralis, I. pollens, I. panicoides, I. proeurrens, I. reclivis, Lasiacis ligulata, Manisuris loricata, Mesosetum loliiforme, Olyra cordifolia, O. micrantha, O. obliquifolia, O. taquara, Panicum echinulatum, P. trachystachyum, P. versicolor, Paspalum dispar, P. erianthum, P. melanospermum, P. peclinatum, P. rupestre, Piresia goeldii, Sacciolepis pungensandSporobolus cubensis.The counts of 2n= 80 forPaspalum secansand 2n= 20 forAxonopus affinisdiffer from the single previous record for each of these species.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10688.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

The force that induces orientation movement of inclined or bent woody stems is generated in reaction wood even in young terminal stems with a large proportion of soft tissues to secondary xylem. Compression wood formed in pine as a response to inclination expands longitudinally after the stresses are released by sawing it from the stem. The increment of length of compression wood when sawed is equal to the decrement of its length which occurs during drying. This suggests that stresses developed by compression wood in the stem are related to imbibition of water by its cell walls. Not all compression wood develops tensile forces in the stem. Neutral compression wood was observed in the lower portion of inclined stems of pine. Tension wood in poplar develops contractile forces in the stem during its aestival maturation. However, when harvested before developing contractile forces in situ, it develops such forces during drying. This suggests that in poplar the mechanism which produces forces responsible for orientation bending also involves changes in cell wall hydration.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10689.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

The megaspore ofMarsileahas an exospore composed of several layers and is contained within the original megasporangial wall (making it technically a megasporangium). Upon contact with water there is an almost explosive unrolling of the megasporangial wall and expansion of the spore wall layers into a complex structure, part of which has not been previously described. The dynamics of the hydration process and the resultant structures are described.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10690.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

Chromatographic and spectrophotometric techniques were used to identify the anthocyanin pigments present inMimulus cardinalisand its related species of sectionErythrantheof the genusMimulus(Scrophulariaceae). On the basis of rigorous tests, the flowers ofM. cardinaliswere found to contain pelargonidin‐3‐glucoside, pelargonidin‐3‐rhamnoglucoside, the caffeoyl ester of pelargonidin‐3‐glucoside, cyanidin‐3‐glucoside, cyanidin‐3‐rhamnoglucoside, and the caffeoyl ester of cyanidin‐3‐glucoside. Qualitatively all members of the group contain these six anthocyanins exceptM. lewisii.All of its populations lack the pelargonidin glycosides and some lack, in addition, the cyanidin‐3‐rhamnoglucoside. The striking differences in flower color and intensity appear to be due to quantitative differences not here analyzed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10691.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

Aqualinderella fermentansis described as a new genus and species in the order Leptomitales of the biflagellate, aquatic phycomycetes. Based upon pure as well as gross cultures, an account is given of its germination, its bipolar, unicellular, vegetative thallus, and its reproductive structures. The genus is distinguished particularly by an exceptionally coarse, digitately divided and thick‐walled extramatrical body. The species is unique among known true fungi in that it combines a strictly fermentative metabolism with a requirement for high CO2. It is specially adapted to grow saprophytically in warm, stagnant waters on submerged fruits and has been found in equatorial Africa, Central America, and the southern United States.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10692.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

Replicas and ultrathin sections of the wood of two Paleozoic genera,CallixylonandCordaites, were examined with the electron microscope. The pattern of wall layering ofCallixylonclosely resembles that of extant plants. An electron‐dense compound middle lamella markedly thickened at the corners of cells, a thin, electron‐transparent S1layer of the secondary wall, and a thick, electron‐dense, partially decayed S2layer of the secondary wall are evident in transverse sections of tracheids. No S3layer seems to be present. The structure of the bordered pit‐pairs ofCallixylonis described in detail. The slitlike outer pit apertures are conspicuously narrower and shorter than the inner pit apertures. Both sections and replicas of the bordered pit‐pairs display pit membranes lacking tori. Microfibrillar structure is obscure in both sections and replicas ofCallixylonwood. Replicas of the bordered pits ofCordaiteswood are very similar to those ofCallixylon.Pit membranes lack tori, and microfibrillar structure is not very discernible. Knowledge about the evolution of the torus is summarized. It is postulated that the type of pit membrane ofCallixylonandCordaites, which is very homogeneous in structure and lacks a torus, represents a primitive condition among gymnosperms from which structurally more complex pit membranes and the torus later evolved.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10693.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

Anatomical changes in the laminar abscission zone of primary leaves ofPhaseolus vulgarisL. ‘Red Kidney’ have been examined in conjunction with the regulation of abscission by growth substances. Quantitative measurements were made of the frequency of vascular obstructions (tyloses, callose plugs). The development of abscission was correlated with an increasing frequency of tyloses and other plugging materials in the xylem of the abscission zone coupled with the dissolution of callose from the abscission zone sieve tubes. These changes were accelerated in petiole explants in which abscission was stimulated by either ethylene or auxin and were suppressed in explants in which abscission was inhibited by auxin.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10694.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

A re‐examination of the mode of vegetative nuclear division inNeurospora crassawas facilitated by the availability of the mutant “clock” which produces definite growth bands. Since the growth rhythm is correlated with nuclear divisions, stained mycelial mats of this mutant prepared at intervals from the beginning of a growth period provided a sequence of stages of division. In a 28‐hour period the following broad features of nuclear behavior were observed: In the early part of the period during rapid mycelial growth, dividing elongated nuclei predominated. At the end of the period the mycelium contained mostly rounded resting nuclei. In the middle of a growth period nuclear forms of various degrees of annularity occurred along with elongated and rounded nuclei. Elongated and rounded nuclei completed division cycles without change in form, although the corresponding stages of the two types were similar. Elongated nuclei assumed a spiral form at the beginning of division. As division proceeded, relaxation of the nuclear gyres was accompanied by a visible duplication of the chromatin thread and the appearance of chromomere‐like bodies on the daughter threads. One of the chromomere‐like bodies became displaced and was interpreted to be a chromosome or a segment of a chromosome that acts as a mitotic center. All the chromosomes were found to be interconnected and to act as a unit throughout the division cycle. Only after the separation of the daughter chromatin threads could seven chromosomes be counted. Electron microscopic studies complemented the observations with the light microscope. On the basis of the evidence it was concluded that the vegetative nuclear division inNeurosporadiffers from the classical mitotic pattern in the following respects: (1) absence of visible centrioles, (2) the presence of interconnected chromosomes, (3) the comparatively late appearance of countable chromosomes, and (4) the frequent presence of interzonal connections between separating chromatin threads.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10695.x

出版商:Wiley    

年代:1967

数据来源: WILEY

摘要:

In 1943 L. R. Wilson described some scattered elater‐bearing spores found in a Middle Pennsylvanian coal ball from What Cheer, Iowa, asElaterites triferens.The spores, averaging 60μin diameter, with a trilete scar on the proximal surface and three conspicuous elaters attached to their distal surface, have now been found in a fragment of a cone from the same locality. The cone is similar toCalamostachysin having whorls of sporangiophores, each with four adaxial sporangia, and some secondary xylem at the nodes, but it possibly differs in lacking sterile bracts.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1967.tb10696.x

出版商:Wiley    

年代:1967

数据来源: WILEY