Showing papers in "Botanical Gazette in 1919"
TL;DR: In this paper, the authors present a compendium of the contributions of all previous workers dealing with the phenomena of succession in vegetation, including the work of the various students of succession, conscientiously and sympathetically presented.
Abstract: CLEMENTS has brought together in a satisfactory way and in sumptuous form the contributions of all previous workers dealing with the phenomena of succession in vegetation.' The work of the various students of succession is conscientiously and sympathetically presented, and with great fulness. So admirably is this work done that it will henceforth be largely unnecessary to refer to original publications, prior to the appearance of this work, in order to get the substantial views of the various authors. The work is thus a compendium of our knowledge and theories bearing on the phenomena of succession. In the field covered by this work, CLEMENTS is himself a major contributor, and in no previous work has he contributed so much new material on the subject as this work includes. No more can be attempted here than to touch a few of the high spots. As previously, CLEMENTS treats the formation as an organism, with structures and functions like an individual plant. As compared with previous studies by the same author, greater stress is placed on development and less on habitat. To the reviewer this seems a distinct step forward, although many workers, especially in Europe, will continue to emphasize habitat as the controlling factor in classification. The formation is defined as \"the climax community of a natural area in which the essential climatic relations are similar or identical.\" Thus CLEMENTS' formation, as here presented, departs materially from the concept of the Brussels Congress, but agrees essentially with the \"climax formation \" of the reviewer, and with the still earlier \" climatic formation \" of SCHIMPER. SCHIMPER, however, probably failed to recognize that his \"climatic formations\" was really the topmost member of a series of his \"edaphic formations.\" A number of new terms of classical origin are introduced in this volume, as is the wont of the author. Perhaps the most important of these is \"sere,\" a term used to include the entire successional series leading up to the climax. This term is used, rather than its essential equivalent \"series,\" because of its adaptability in combination, as in xerosere (a xerarch series), etc. CLEMENTS' treatment of the term \"climax\" is in general harmony with the often expressed interpretation of the reviewer; \"the climatic formation is the real climax of the successional
51 citations
TL;DR: The vegetative thallus of Actinomyces consists of a mycelium composed of profusely branching hyphae, the terminal growing portions of which are densely filled with protoplasm.
Abstract: 1. The vegetative thallus of Actinomyces consists of a mycelium composed of profusely branching hyphae, the terminal growing portions of which are densely filled with protoplasm. Toward the center of the thallus the vacuoles increase in size and may be associated with the presence of metachromatic granules, the latter having nothing in common with bacterial endospores or "micrococci," for which they were mistaken by early observers. 2. The vegetative mycelium attains an extent incomparably greater than the branching figures recorded for bacteria of the acid-fast group, and the hyphae lack the uniformity in diameter generally characteristic of the Schizomycetes. 3. The aerial mycelium produced on suitable substrata by most species occurs usually in the form of a mat of discrete fructifications; but in other species these fructifications are frequently combined to form numerous and peculiar erect Isarioid sporodochia. 4. In any case each individual fructification represents a well characterized sporogenous ...
51 citations
TL;DR: Air-dry seeds of Tilia americana, Sambucus canadensis, and Rubus Idaeus do not germinate when placed on a moist substratum at room temperature, and much still remains to be learned concerning the conditions necessary to reach perfect germination.
Abstract: General.--Air-dry seeds of Tilia americana, Sambucus canadensis, and Rubus Idaeus do not germinate when placed on a moist substratum at room temperature. In no case does water absorption seem to be the limiting factor. Air-dry seeds planted in the soil over winter give low percentages of germination. Tilla--Seed coats are not the cause of dormancy, although they may serve to lengthen the dormant period. A state of dormancy exists in the endosperm or embryo, or both. Seeds with coats removed after-ripen at temperatures slightly above freezing. At 0-2⚬ C. seeds after-ripen, but do not germinate. At 4-6⚬ C. both after-ripening and germination take place. Seeds after-ripened at 0-2⚬ C. germinate readily at 10-12⚬ C., but very poorly at room temperature. Once germination has begun growth proceeds best at temperatures above 12⚬ C. As after-ripening, progresses the hydrogen ion concentration increases, as do also the water holding capacity and the oxidase and catalase activities. The greatest amount of free acid...
31 citations
TL;DR: A high capacity for nitrate absorption and storage must be an important factor in making Amaranthus a very successful competitor against cultivated plants, so effectively withdrawing as it does the nutrient element most commonly limiting plant production.
Abstract: 1. There is a large amount of nitrate in the organs of A. retroflexus. The stem and branches are the primary nitrate storage organs. The rate of nitrate absorption increases with the aging of the plant, perhaps partly being due to the development of the root system with numerous branching rootlets, increasing the radius of the feeding area from a few inches to 2 ft. or more. 2. This high capacity for nitrate absorption and storage must be an important factor in making Amaranthus a very successful competitor against cultivated plants, so effectively withdrawing as it does the nutrient element most commonly limiting plant production. It would be interesting to know how generally and to what degree weeds possess this power. 3. The carbohydrates and nitrogen compounds fluctuate throughout the growing period. The fluctuation of the carbohydrates is in the reverse order of the nitrogen compounds. This inverse ratio is not a truly mathematical constant, but in general when the carbohydrates are high the nitrogen...
26 citations
TL;DR: The increase losses of broad-leaved trees in spring occasioned by foliation are in proportion to the leaf areas exposed, and are closely controlled by weather conditions, but in the main are similar to increased losses of conifers.
Abstract: 1. Autumn transpiration losses from conifers are just as great as or even greater than those from broad-leaves. 2. The decrease in water losses from broad-leaved trees resulting from defoliation is gradual, and not greatly unlike the decrease shown in the transpiring power of conifers. 3. Winter transpiration losses from conifers are only 1/55-1/251 as great as those in autumn. 4. The increased losses of broad-leaved trees in spring occasioned by foliation are in proportion to the leaf areas exposed, and are closely controlled by weather conditions, but in the main are similar to increased losses of conifers. 5. Winter transpiration losses from conifers are scarcely greater than those from defoliated stems of broad-leaved trees.
22 citations
TL;DR: The book is written in attractive style, and the material is well selected, and is a commendable effort o differentiate secondary-school botany from university botany, which is a foundation for agricultural study rather than a study of agriculture.
Abstract: the family are given concisely, as well as the more interesting features of the history, distribution, and uses of the more important economic representatives. The book is written in attractive style, and the material is well selected, and is a commendable effort o differentiate secondary-school botany from university botany. The numerous half-tones are of unusually good quality. MARTIN2 has attempted the same task, except that his book is more specifically directed to the botanical needs of the student of agriculture. The first part deals with flowers, seeds, cells, roots, stems, buds, leaves, etc. The application to agriculture consists chiefly in the fact that economic plants are used as illustrative material. For example, oats, corn, wheat, pineapple, tomato, etc., are made to show the usual fundamental facts of morphology. The second part presents an outline of the plant kingdom, from Thallophytes to Angiosperms, along with chapters on ecology, evolution, heredity, and plant breeding. The presentation throughout is botanical rather than agricultural, a foundation for agricultural study rather than a study of agriculture. The line drawings are not as well done or as accurate as they should be, and the illustrations in general are in contrast with the excellent presswork and the easy and pleasing style of presentation.-F. L. STEVENS.
20 citations
TL;DR: The senior writer of this paper suggested in a previous publication that invertase is secreted by the roots, so it seemed advisable to investigate the problem and the results obtained constitute the basis for this paper.
Abstract: The fact that green plants are able to absorb certain organic substances by means of the roots, and to utilize these substances, suggests the question whether the roots of plants secrete enzymes in a manner comparable to various fungi, digesting in the culture medium, etc., the various organic substances that might be supplied. Various investigators have incidentally touched the subject, but the evidence obtained is conflicting and not at all conclusive. LAURENT (3) reported the inversion of saccharose when this sugar was present in the culture media, and he ascribed this to the enzyme invertase secreted by the roots of corn or of peas. Starch was likewise transformed, but LAURENT ascribed this transformation to diastase secreted by the seed. MAZE (4) reported inversion of saccharose, but in i9ii (5) he stated that there was no enzyme secretion by the roots, and that starch was absorbed directly. WOHLLEBE (8), investigating the secretion of amylase by roots, came to the conclusion that there was a very weak secretion of amylase by the root hairs, and in some cases secretion of amylase was effected by the disconnected root-cap cells. The senior writer of this paper suggested in a previous publication (2) that invertase is secreted by the roots. In view of the indefiniteness of information on the subject, it seemed advisable to investigate the problem. The first experiments were made on the secretion of amylase, and the results obtained constitute the basis for this paper. Pfeffer's was the nutrient solution employed. It was made up according to the following formula: Ca(NO3)2 4 gm., KNO3 I gm., K2HPO4 I gm., MgSO4 I gm., KCl 0.5 gm., FeCl3 I00 mg., distilled water 6 1. Merck's soluble starch was used throughout the experiments.
17 citations
TL;DR: Oenothera rubrinervis is a half mutant, produced by the copulation of a mutated gamete with a normal velutina gamete of O. Lamarckiana, and the internal constitution, which causes the mass mutation, is not in itself a cause for further mutability.
Abstract: 1. Oenothera rubrinervis is a half mutant, produced by the copulation of a mutated gamete with a normal velutina gamete of O. Lamarckiana. 2. In consequence, it produces about one-fourth empty grains, a mass mutation of about one-fourth pure or double mutants, and one-half specimens of O. rubrinervis, which will repeat the splitting. 3. The pure or double mutant is called O. mut. deserens. It is very similar to O. rubrinervis, but the leaves of its young rosettes and the bracts of its flower spike are broader and more even. 4. O. mut. deserens is constant from seed. It has no hereditary empty grains. 5. The formula for the self-fertilization of O. rubrinervis is therefore O. (deserens + velutina) = des. x des. + velu. x velu. + des. x velu. The first combination gives the mass mutation, the second the empty grains, the third the normal plants of O. rubrinervis. 6. In crossing with other species the two kinds of gametes will produce twin hybrids, as, for example, laeta and velutina. This assertion has been...
16 citations
TL;DR: Attempts to connect succulency in a causal way with the presence of salts in the soil, or in the plant with the well known high acidity of many of these forms, or with any purposeful development of water storage capacity have been inadequate.
Abstract: Succulents may be characterized as plants in which the parenchymatous elements show an exaggerated development with relation to the more rigid tissues, and, unlike pith or medullary tracts, the masses of thin-walled cells remain distended and turgid. The liquid contents of such cells may or may not contain much dissolved material. The disposition of the water-holding tracts varies from leaves to stems and roots, but in all cases the most important general effect is one of massiveness, and the surfaces of succulent plants may in such forms as the barrel cacti bear the smallest possible proportion to the mass, that of a globe. The ecologist recognizes two general types of succulents, those of the arid regions, which are of a xerophytic character, exemplified by the cacti; and the halophytes or fleshy seashore plants, also at home in alkaline areas. The plants of the two types are quite unlike in their transpiratory relations. The desert succulents may lose water so slowly that an existence of several years may be maintained upon the water in the thin-walled tracts.' On the other hand, the halophytes or fleshy shore plants may flag and wilt as readily as any thin-leaved form, due to the rapid loss of water from the surfaces. The origination of these striking forms has been the subject of much speculation, but all attempts to connect succulency in a causal way with the presence of salts in the soil, or in the plant with the well known high acidity of many of these forms, or with any purposeful development of water storage capacity, have been inadequate. Our concurrent observations and experiments may be briefly summarized as follows: I. A Castilleja native to the region about the Coastal Laboratory, at Carmel, California, includes two habitat forms, genetically identical, one with thin leaves growing in the open forest formation,
16 citations
TL;DR: The expressed sap from barley plants grown in water, sand, and soil cultures under controlled conditions has been examined and the concentration in the sap was found to be very much greater than in the soil solution.
Abstract: The expressed sap from barley plants grown in water, sand, and soil cultures under controlled conditions has been examined with the following results: 1. The osmotic pressures in the sand and water cultures are reflected in the cell sap of the tops and roots. 2. The electrical conductivity of the nutrient solution has a marked influence on the conductivity of the sap. This is as marked for the tops as for the roots. The conductivity of the plant sap is from 4 to 50 times greater than that of the nutrient solution. 3. The sap from the tops of all plants grown in sand and soil cultures or water cultures of different concentrations and reactions had almost the same PH value, approximately 6.0. 4. Samples of sap from plants grown on 6 different soils under the same climatic conditions were analyzed for important elements. In every case the concentration in the sap was found to be very much greater than in the soil solution. 5. The dynamic nature of the relation between the soil solution and the plant is empha...
14 citations
TL;DR: The order of the development of the floral parts of Scrophularia marylandica is calyx, stamens, corolla, and pistil, and the mature embryo sac contains one egg, two large synergids, an endosperm nucleus, and three antipodal nuclei which soon degenerate.
Abstract: 1. The order of the development of the floral parts of Scrophularia marylandica is calyx, stamens, corolla, and pistil. The stamens and the corolla arise from a common outgrowth. 2. The archesporium of the megaspore consists of a single hypodermal cell, which functions as a megaspore mother cell. 3. The megaspore mother cell by two successive divisions gives rise to an axial row of four potential megaspores; the embryo sac arises from the chalazal one, while the other three degenerate. 4. The mature embryo sac contains one egg, two large synergids, an endosperm nucleus, and three antipodal nuclei which soon degenerate. 5. A secondary endosperm nucleus, which grows larger as it migrates toward the egg, was observed. A polar nucleus from the chalazal end was seen to fuse with a polar nucleus from the micropylar end. 6. The first division of the fertilized egg is transverse, and is followed by a longitudinal division of the chalazal nucleus, while the other nucleus fails to divide until later. 7. The nucellu...
TL;DR: Results negative the statements of EWART that excessive drying changes dormant protoplasm to such an extent that the essential molecular groupings cannot be re-established under conditions for germination.
Abstract: Another paper by the same authors describes some experiments made to test the effects of desiccation on vitality of seeds. The seeds of grains and grasses will withstand drying to less than i per cent without material loss in germination. Blue grass and Johnson grass can even be dried to o.i per cent of moisture without loss in germination, but vigor is greatly reduced in the blue grass. Still further loss of vigor occurred in the blue grass when dried in vacuo at Ioo' C. for 6 hours, but the germination percentage was not materially reduced. These results negative the statements of EWART that excessive drying changes dormant protoplasm to such an extent that the essential molecular groupings cannot be re-established under conditions for germination.-C. A. SHULL.
TL;DR: Chemical analyses of Puget Sound bog waters give results similar to those reported for other American bog waters, and the toxicity of bog water to Tradescantia cuttings seems to be connected with the matter in it that is in a colloidal state.
Abstract: 1. Bog water gives a precipitate on standing a few hours after saturation with electrolytes 2. It also gives a precipitate on standing a year or more without electrolytes. 3. The filtrate from the precipitation with (NH4)2SO4, when dialyzed until free from sulphates, is not toxic to the root hairs of Tradescantia cuttings. 4. Bog water, when dialyzed for the same length of time as this filtrate, is toxic to these root hairs. 5. The distillate from bog water gives no precipitate with electrolytes, is much less acid than bog water, and is not toxic to these root hairs. 6. The concentrate obtained when bog water is distilled to approximately one-sixth of its original volume gives a heavier precipitate with electrolytes than does bog water. It is also more acid and more toxic to these root hairs. 7. The residue from complete evaporation of bog water is a brownish powder which is soluble in cold water, insoluble in alcohol and gasoline, and practically insoluble in ether. 8. This water solution of the residue ...
TL;DR: The stem of Dioon spinulosum is large enough to demonstrate the cause of the girdling habit and to bring it into alignment with certain angiosperms of the same habit.
Abstract: 1. The cotyledons of Dioon spinulosum vary in number from 2 to 4, and they are often lobed and divided so as to appear greater in number. In rare cases the cotyledonary sheath is undivided except near the tip. 2. They are multifascicular, like those of Ceratozamia and Microcycas, rather than like those of Zamia and Cycas, which have but few strands. 3. The arrangement and orientation of the vascular strands of cotyledons, hypocotyl, stem, leaves, and root do not differ in any marked degree from the general cycad arrangement. 4. The stem is large enough to demonstrate the cause of the girdling habit and to bring it into alignment with certain angiosperms of the same habit. 5. There is no extrafascicular cambium or any other vestige of polystyle.
TL;DR: In this article, the minimum moisture content of the subsoil of the buffalo-grass formation in the southwestern part of that state, where the climate is typically semi-arid, and in the prairiegrass formation near Lincoln, which lies within the limits of the humid region.
Abstract: 1. During a 6-year period, in which the weather was exceptionally favorable for a study of the minimum moisture content of the subsoil, moisture studies were carried out on Nebraska prairies, both in the buffalo-grass formation in the southwestern part of that state, where the climate is typically semi-arid, and in the prairie-grass formation near Lincoln, which lies within the limits of the humid region. The fields were sampled to a depth of 6 ft. or more, and in the case of every sample the hygroscopic coefficient as well as the moisture content was determined, and the moisture condition is expressed as the ratio of moisture content to hygroscopic coefficient, this having the advantage of expressing the relative moistness while at the same time indicating whether either free water (1.1 or above) or growth water (1.6 or above) is present, and if so the amount of each. 2. The subsoils of the semi-arid prairies were characterized by their persistent dryness. Usually throughout more or less of the first 6 f...
TL;DR: It is the opinion of the writer that future study will prove that this phenomenon may occur in other species of Dictyuchus, and perhaps even in other members of the Saprolegniaceae.
Abstract: 1. In the characteristics of its non-sexual reproduction the fungus which is the subject of this paper shows itself to be a member of the genus Dictyuchus. No sexual reproduction was observed, however; hence it cannot be assigned to any of the recognized species. 2. During the formation of spores within the sporangium, the walls of adjacent spores unite with one another and with the enveloping sporangium membrane, to form a polygonally chambered, indehiscent structure. In this respect Dictyuchus differs fundamentally from all other Saprolegniaceae, save perhaps the doubtful genus Aplanes. 3. The zoospores which emerge from the sporangiospores come to rest and encyst as is customarily described. From these encystedspores in turn, however, laterally biciliate zoospores may emerge. This repeated emergence of laterally biciliate zoospores has not previously been reported in any member of the Saprolegniaceae. 4. It is the opinion of the writer that future study will prove that this phenomenon may occur in othe...
TL;DR: The structure of the walls of the cambium and the development of the pitting in the elements of the xylem and phloem in Pteridophyta, Gymnos permae, and Angiospermae deserve more careful consideration in discussions concerning the phylogenetic significance of the so-called rims or bars of Sanio, than they have received heretofore.
Abstract: 1. Bandlike thickenings of the middle lamella and scalariform primary pit areas are characteristic of tracheids which have scalariform bordered pits. They are widely distributed among the Pteridophyta, Gymnospermae, and Angiospermae. 2. The middle lamella frequently retains its typical scalariform structure after the secondary wall has lost it. 3. In the Gymnospermae, as well as in the Pteridophyta and Angiospermae, there appear to be transitions between primary membranes of this type and others in which the scalariform structure is profoundly modified. 4. The comparative anatomy and ecology of the Pteridophyta, Gymnospermae, and Angiospermae afford considerable evidence which suggests that the types of unconformity and peculiar bandlike thickenings of the middle lamella (so-called bars or rims of Sanio) which occur in certain Pteridophyta and Angiospermae, as well as in many Gymnospermae, are concomitants of processes of modification or reduction in tracheary pitting. 5. The structure of the walls of the...
TL;DR: These new studies show that in widely separated groups of animals which are usually dioecious various grades and degrees of maleness and femaleness in a single individual are common, and are particularly suggestive of the probability that sex differentiation in dIOecious forms and in hermaphrodite forms is essentially the same process.
Abstract: Through the resent researches of GOLDSCHMIDT (II, I2, I3), BANTA (I), WHITMAN, RIDDLE, and their associates (see especially summaries by RIDDLE 22, 23), and LILLIE (I7, I8), the facts of intersexualism have acquired a significance which must be considered by any theory of sexuality and sex determination These new studies show that in widely separated groups of animals which are usually dioecious various grades and degrees of maleness and femaleness in a single individual are common Judged as entire individuals, such "intersexes" or "sex intergrades" may be predominately male or female, or there may be various grades in the relative development of maleness and femaleness, giving in some cases at least functional hermaphrodites Along with these there may be individuals that are only male or female An individual sex organ may start development as of one sex and change to the other, or there may be a decidedly simultaneous development of male and female sex organs, as in the fully functional hermaphrodite The more remote secondary sex characters also exhibit characteristics of maleness, femaleness, or various grades of modifications that are intermediate Such development of intersexuality in forms usually considered as dioecious is evidence that even in dioecious forms sex is not necessarily determined at fertilization, and that sex is not alternative and irreversible for an individual or even for a sex organ The data are particularly suggestive of the probability that sex differentiation in dioecious forms and in hermaphrodite forms is essentially the same process, and thus that sex determination is on the same fundamental basis in both plants (which are prevailingly hermaphrodite) and animals (which are prevailingly dioecious) In plants the most intimate association of the two sporophytic sex organs is seen in the so-called perfect flowers The opposite
TL;DR: Undercooling of the tissues occurs to a greater degree in such herbaceous plants as possess protective epidermal coverings than in plants not so protected.
Abstract: Undercooling of the tissues occurs to a greater degree in such herbaceous plants as possess protective epidermal coverings than in plants not so protected. The undercooling in such plants is not due to substances in the cell sap, but mainly to the prevention of inoculation from ice formed on the surface of the tissue. A method is given for determining electrically the temperatures within leaf tissues.
TL;DR: In this article, an organism capable of forming nitrites from ammonia, isolated in a pure state from Wooster soil after many unsatisfactory attempts, was described, which is the result of a long period of study.
Abstract: As a part of the physiological investigations upon nitrification carried on in this laboratory, the isolation of pure cultures of the nitrite-forming organisms became a necessity. Since difficulties in the isolation of these organisms have been encountered by many workers in the field of soil bacteriology, and since no accurate description of the organisms of nitrification from North American soils has been published as yet, it was deemed advisable to describe the organisms responsible for the formation of nitrites in the Ohio soils and the methods used in their isolation. The following contribution, which is the result of a long period of study, is here given to describe an organism, capable of forming nitrites from ammonia, isolated in a pure state from Wooster soil after many unsatisfactory attempts.
TL;DR: The type of the genus A. Henryi is shown to be one of the most primitive forms of Marattiaceae by its simply pinnate leaves and simple stelar structure, and it is inferred that Archangiopteris represents the form of a primitive type to which the ancestor of AngiopterIS may have belonged.
Abstract: The Marattiaceae constitute a small family which may be regarded as the survivor of a much larger group. At present only 6 genera are known: Archangiopteris,I Macroglossum, Angiopteris, Marattia, Christensenia (Kaulfussia), and Danaea. A rchangiopteris was first discovered by A. HENRY in Yunnan and was published in i899 by CHtRIST and GIESENHAGEN as a genus connecting Angiopteris with Danaea. The type of the genus A. Henryi is shown to be one of the most primitive forms of Marattiaceae by its simply pinnate leaves and simple stelar structure.3 According to GWYNNE-VAUGHAN,4 the mature stem of Archangiopteris retains a stage which is rapidly passed through by the young plants of Angiopteris and other genera. The same seems to hold true as to the form of the leaves. As far as I have observed Angiopteris in its habitat in Formosa, the first 2 or 3 leaves from a young stock usually are simply pinnate, but die before they reach maturity and become fertile. The pinnae of these first leaves are much larger than of those that follow, and closely resemble those of Archangiopteris in shape and size. We may infer, therefore, that Archangiopteris represents the form of a primitive type to which the ancestor of Angiopteris may have belonged. Archangiopteris most closely related to Macroglossum,5 recently established by COPELAND, both in the simply pinnate fronds and
TL;DR: The writer will show that these plant impressions differ so fundamentally from all known cryptogamic sporophylls that it will be necessary to establish for their reception a new genus.
Abstract: The plant impressions which form the subject of this paper have in part been known for several decades, but the discovery by the writer of the key to their important and very interesting nature came as a pleasant incident in monographic studies of the very large and varied flora of the Maryland Carboniferous, and it is believed that the testimony which they contribute to a discussion of the problem of the phylogeny of the vascular cryptogams will justify the publication of this paper in advance of the large systematic work upon which the writer is engaged. These plant impressions were long regarded as the sporophylls of Lepidostrobus (Lepidophyllum), and latterly (i6) certain of them were thought to be the microsporophylls of some yet unknown type of Lepidostrobus or Lepidocarpon whose sporangia by their complicated form, not then understood, differed from those of the known species of Lepidophyllum, but the writer will show that they differ so fundamentally from all known cryptogamic sporophylls that it will be necessary to establish for their reception a new genus. The most distinctive feature of this group is a large lamellar sporangiophore developed in the radial plane of the strobilus from the superior (ventral) face of the sporophyll pedicel, bearing two large elongate sporangia, one upon each side, pannier-like; and it is this character which has suggested the name Cantheliophorus,
TL;DR: A comparative study of the foliar transpiring power of Tilia as recorded in the field for dune environments (i) preceded this work, which is an extension of the former investigations, and is concerned with the data recorded for the same species as obtained from a wide range of habitats on clay soils.
Abstract: A comparative study of the foliar transpiring power of Tilia as recorded in the field for dune environments (i) preceded this work, which is an extension of the former investigations, and is concerned with the data recorded for the same species as obtained from a wide range of habitats on clay soils. The methods employed were essentially the same as described in the former discussion of the dune series. A 3 per cent cobalt chloride standard paper was used in all the work for determining the relative transpiring power, and was applied by means of the clip devised by LIVINGSTON (4). As in the former experiments, readings were taken on two leaves at each station, the same leaves being employed in subsequent readings. Records were taken at approximately hourly intervals, and as recorded represent the average of four to six readings. Curves are plotted for both leaves. The slight difference observed in the readings for the two leaves, which occasionally became considerable, was in most instances attributed to the relative maturity and specialization of the epidermis and cuticle. Measurements of the chief environmental factors were recorded, and special features of the environment taken into consideration. The chief factors measured were evaporation, relative humidity, atmospheric temperature, soil temperature, wilting coefficient, and growth water. The occurrence of alternate sun and shade, velocity of the wind, fog, and passing thunder showers were special features which were found to bear a definite relation to the oscillating behavior of the transpiration stream. Measurement and computation of these factors were carried out in the same manner as in the preceding experiments.
TL;DR: All the members of this interesting group, which is, as M. BEBB and W. ROWLEE (i900) rightly stated, clearly defined from the other sections of the genus, are discussed.
Abstract: In my paper on Mexican willows (BOT. GAZ. 65:22. i9i8) I have already dealt with some species of this well marked and entirely American section. In this article I intend to discuss all the members of this interesting group, which is, as M. S. BEBB (i89i) and W. W. ROWLEE (i900) rightly stated, clearly defined from the other sections of the genus in both. the New and the Old World. ANDERSSON (i858) was the first to recognize the close relationship of species like S. sessilifolia Nutt., S. Hindsiana Benth., and S. taxifolia Kth: to S. longifolia Muhl. Unfortunately he misunderstood most of the species described by NUTTALL, and therefore he did not give, even in i868, a proper analysis of the forms of this section. In i900 W. W. ROWLEE (Bull. Torr. Bot. Club 27:247) made an attempt to rehabilitate all of NUTTALL'S species, and described several new species and varieties from the southwest, especially from California. His interpretation of NUTTALL'S species, however, is not free from grave errors owing to the lack of sufficient type material. Later C. V. PIPER studied those types of NUTTALL which are preserved in the British Museum, and communicated his notes to C. R. BALL, who in I9I5 (BOT. GAZ. 60:49) was able to identify S. sessilifolia and S. fluviatilis Nutt. I have not seen the types in the British Museum, but I have photographs of NUTTALL'S specimens of S. exigua, S. macrostachya, and S. melanopsis from the Herbarium of the Academy of Science at Philadelphia. Besides this I have also examined a few of NUTTALL'S willows at the Gray Herbarium, which also contains some cotypes of forms described by ANDERSSON. Photographs and fragments of ANDERSSON'S types from the Hookerian Herbarium at Kew are now in possession of the Arnold Arboretum, and Professor W. W. ROWLEE kindly sent me the types of his new species and forms so far as they are preserved in the Herbarium of Cornell
TL;DR: In order to bring out the characters of the new plant it is necessary partly to redescribe the supposed parents, especially since the descriptions in the manuals omit several significant characters.
Abstract: From time to time references have been made to supposed hybrids between the perennial sunflowers, but there has been no systematic investigation of the subject. Such hybrids, if formed, might in many cases reproduce vegetatively, and so give rise to an essentially uniform group of plants of considerable extent, having the aspect of a true species. At Boulder, Colorado, Helianthus orgyalis and H. Maximiliani have been growing in close proximity for a number of years. There has appeared close to these plants a distinct form which can hardly be anything but a hybrid between the two. Possibly such hybrids will be found growing wild in Nebraska, Missouri, or Texas, if anywhere the ranges of the parent species overlap. In order to bring out the characters of the new plant it is necessary partly to redescribe the supposed parents, especially since the descriptions in the manuals omit several significant characters. The 3 plants involved will be distinguished by the following numbers: (i) H. orgyalis DC.; (2) H. orgyaloides, nov. (the presumed hybrid); (3) H. Maximiliani Schrad. Stems: (I) very smooth and glaucous to top, much branched, the branches slender; (2) essentially smooth, but roughish to the touch above, nearly as stout as in Maximiliani, and with few branches or short peduncles as in Maximiliani; (3) stout, little branched, scurfy, with matted white hairs, thinly hairy at top. Leaves: (i) linear, crowded on stem, i-nerved, but with a strong marginal nervure; surface glabrous; margins slightly undulate, with mere traces of obsolete teeth; width of stem leaf 6 mm.; (2) linear, appearing as in orgyalis, but up to I2 mm. broad, rough to the touch, remotely and indistinctly subdentate; a continuous but looped submarginal nervure; (3) broadened, narrow lanceolate, grayish, more or less scabrous on both sides, margins remotely and feebly dentate; no continuous marginal nervure; width of stem leaf 26 mm. Peduncles: (i) slender; (2) stoutish; (3) stout. Disk: (i) dark; (2) yellow, pale green in bud; (3) yellow.
TL;DR: The earliest stage of Pluteus Admirabilis showed a differentiation into primordia of stipe, pileus, and hymenophore, and no entirely undifferentiated primordium of a basidiocarp was obtained.
Abstract: Pluteus Admirabilis 1. No entirely undifferentiated primordium of a basidiocarp was obtained. The earliest stage secured showed a differentiation into primordia of stipe, pileus, and hymenophore. 2. All parts of the young basidiocarps are covered with free ends of hyphae which lie more or less parallel to each other. The primordium of the hymenophore is distinguishable by the smaller cells composing it, with denser protoplasmic contents. It develops at the angle of junction between pileus and stipe. This soon becomes a definite level palisade layer. It is entirely exogenous in origin. 3. There is a strong epinastic development in the margin of the pileus and it becomes so strongly incurved that the filaments on its margin intermingle with those on the surface of the stipe. This occurs while the hymenophore is still in a level palisade condition. 4. The gills originate as downward growing folds which develop centrifugally, the first folding taking place at the point where the fundament of the hymenophore w...
TL;DR: Although the completed forms of companion cell in the two groups are similar, they have probably been independently evolved and are found in certain regions of some species.
Abstract: 1. Companion cells resembling those of angiosperms in size, in their association with sieve tubes, in their usual location in the angles of the sieve tubes, and in their vertical elongation, are present in the bast of some species of Gnetum. 2. The development of these companion cells, however, is quite different from that found in angiosperms. Whereas, in the latter, each sieve tube and its companion cell are derived from two successive cells in a single row of cambial products, in Gnetum sieve tubes and companion cells are produced from different rows of cambial cells. 3. Although the completed forms of companion cell in the two groups are similar, they have probably been independently evolved. 4. Primitive conditions in which companion cells are lacking, or in which continuous rows of companion cells are present, are found in certain regions of some species. 5. The parenchyma of the wood is formed by those cambial cells which form companion cells; the distribution of the wood parenchyma is consequently...
TL;DR: Zygospores were produced only when 2 strains were contracted whose gametes were compatible, and in none of the hermaphroditic strains did branches of the same hyphae conjugate.
Abstract: 1. In Cunninghamella there does not exist sexual dimorphism. 2. C. echinulata plus and minus, or Mucor V. plus and minus as separated by BLAKESLEE, are unable to form progametes or gametes when contrasted with any one of 26 cultures of C, bertholletiae, 3. Many of these cultures of C. bertholletiae were able to form zygospores when contrasted with certain other cultures of this same species. 4. There exists a selective power in some strains to form zygospores with certain other strains. This condition of pseudoheterothallism cannot be explained at present. 5. There exists a condition in some strains which might be called hermaphroditism. 6. In none of the hermaphroditic strains did branches of the same hyphae conjugate. 7. Zygospores were produced only when 2 strains were contracted whose gametes were compatible.
TL;DR: The maximum of beneficial results was secured from concentrations deadly to insect life, but just a little below the point of first injury to the plant, and high reducing sugar content seemed to be correlated with maximum resistance.
Abstract: 1. Different concentrations of hydrocyanic acid gas gave effects ranging from stimulative to depressive. The maximum of beneficial results was secured from concentrations deadly to insect life, but just a little below the point of first injury to the plant. 2. External factors having important action on the resistance are as follows: (a) wetting the leaves had a beneficial effect on the tomato; (b) reduced temperature and low light intensity during the day preceding fumigation increased resistance. 3. Injury closely paralleled the stomatal movement, increasing as the size of stomatal aperture increased. 4. A higher or lower water supply in the soil affected resistance, through hastening or retarding the growth rate. Rapid growing plants were susceptible to injury, while slow growing plants were more resistant. 5. High reducing sugar content seemed to be correlated with maximum resistance.