Ecology and Evolutionary Biology Commons^™

A Preliminary Report On The Nebraska State Museum, Erwin H. Barbour

Bulletin of the University of Nebraska State Museum (1924–2023)

The Nebraska State Museum has been established a sufficient number of years to make it widely known throughout the state, both by reputation and by personal visits. Incident to a growing clientele and an expanding correspondence, it is expedient that a concise circular letter be issued in bulletin form. Such a pamphlet can be promptly forwarded to inquirers and will offer obvious advantages over individual replies.

Root Behavior And Crop Yield Under Irrigation, Frank C. Jean, John E. Weaver

Papers of John E. Weaver (1884–1956)

More than half of the surface of the earth receives insufficient precipitation
for the most favorable growth of crops. The, best method of making up this deficiency is through the application of water by irrigation. Hence the economical use of irrigation water is one of the chief problems of agriculture in arid regions. Since much more land is available than can be irrigated by the supply of water, even when methods of greatest economy are employed, the welfare of these regions demands that the irrigation water be used as efficiently as possible (cf. Harris, 1916). It has been estimated that …

Some Field Instruments And Their Applications, G. W. Goldsmith

University Studies (University of Nebraska) (1888–1984)

Physiology and ecology depend for their constructive development largely upon the applications of physico-chemical concepts to living organisms and their environment, to their life processes, reactions, and interrelations. A concept is valuable biologically in so far as it can be applied and used as a tool for better understanding of the phenomena related to life. Ecology, as the study of the relations between organisms and their environment and of the interrelations of organisms, depends primarily upon the findings of physiology (Clements, 1905). But to apply physicochemical concepts and hence make them of value to the physiologist or ecologist commonly requires …

Variations In Cytology And Gross Morphology Of Taraxacum Ii. Senescence, Rejuvenescence, And Leaf Variation In Taraxacum, Paul B. Sears

Papers in Ecology

The variability of Taraxacum has frequently been recorded in botanical literature without receiving much elucidation. It is less often an object of investigation than of conjecture and discussion. A few botanists have studied the effect of environmental factors upon Taraxacum, but their results have not cleared away taxonomic difficulties. Systematic botanists have either looked upon the variations in this genus as fluctuations or slight mutations, and then proceeded to lump or split as judgment might dictate. That life history exerts a profound influence upon form seems generally to have escaped attention.

Anthocyan Pigments, Paul B. Sears

Papers in Ecology

Noack has found rhamnose-free flavonol diglucosides to be much more abundant in green leaves than has generally been supposed. In such leaves as he studied he was able to establish the existence of flavonol-anthocyan in couples of similar glucosidal nature, but secured no evidence of aromatic nucleus composition in such cases. He suggests that these couples function as a reduction mechanism during photosynthesis.

Variations In Cytolgoy And Gross Morphology Of Taraxacum, I. Cytology Of Taraxacum Laevigatum, Paul B. Sears

Papers in Ecology

These investigations are the outgrowth of a study, begun in 1914 at the instance of the late Professor C. E. Bessey, of parthenogenesis in Taraxacum vulgare (Lam.) Schrk. and T. laevigatum ( Willd.) DC. These two species are the common ones in central United States, being respectively designated as Leontodon taraxacum L. and L. erythrospermum (Andrz.) by Britton and Brown (3). In 1917 the existence of ameiotic parthenogenesis in both species was confirmed (23) and certain pollen abnormalities briefly described. These abnormalities have invited more critical analysis as a means of throwing light upon certain phases of variation …

Vegetation Mapping, Paul B. Sears

Papers in Ecology

The value of accurate maps of native vegetation as a basis for very practical generalizations can not be questioned. It is obvious that an essential condition for getting accurate maps of large areas is the existence of precise maps of smaller component ones. At present very few precise local maps are available, but it is to be hoped that botanists throughout the country will begin to supplement the efforts of a few of their number who are doing map work of permanent and general' value.

Variation In Taraxacum, Paul B. Sears

Papers in Ecology

To the editor of Science: Since several species of Taraxacum are parthenogenetic and at the same time highly variable they have. looked like tempting material for the study of certain phases of genetics. Moreover their "polysnorphy," as well as that of other parthenogenetic plants, has served as a partial basis for well-known attempts to explain parthenogenesis as due to hybridization.

The Ecological Relations Of Roots, John E. Weaver

Papers of John E. Weaver (1884–1956)

Although considerable progress has been made in the study of root systems of desert plants (Cannon, 1911, 1913; Markle, 1917), very little information is available concerning the roots of other native species. During 1914 the writer investigated the root systems of the prairie plants of southeastern Washington, where the annual precipitation is only 21.6 inches and occurs mostly in the period of rest: Since that time it has been planned to make a comparative study of the roots of prairie plants growing in a more humid region and where the precipitation occurs mostly during the season of plant growth. The …

Changing Diatoms Of Devils Lake, Clarence Elmore

School of Biological Sciences: Faculty Publications

During the summer of 1915 I spent some time at the Biological Station of the University of North Dakota at Devils Lake, investigating the diatoms of the lake. Before this considerable diatom material had been sent to me by Dr. R. T. Young of the University, who is conducting the biological survey of the lake.
The immediate practical object in the survey is to determine the organisms in the lake in relation to the fish that might be able to subsist upon them, and diatoms being the most abundant of microscopic plants, deserve special attention in this connection. At present …

Further Studies In The Ecotone Between Prairie And Woodland, R. J. Pool, J. E. Weaver, F. C. Jean

University Studies (University of Nebraska) (1888–1984)

A series of intensive investigations of the ecological features of the tension zone between prairie and woodland in the Mississippi valley was begun by Weaver and Thiel in 1915. These studies were continued for two seasons in Minnesota and were also extended to the prairies of eastern Nebraska in 1916. These investigations represent the first attempt to attack the prairie-forest problem on a comprehensive scale by means of the quantitative methods of modern ecology. Some of the results secured from these studies have been published as the first paper of a series planned to deal with critical investigations in the …

Amiotic Parthenogenesis In Taraxacum Vulgare (Lam.) Scrk. And Traxacum Laevigatum (Willd.) Dc., Paul B. Sears

Papers in Ecology

The work of which the results are here offered, awaiting detailed presentation in a paper to follow, was begun at the University of Nebraska in 1914, under the direction of the late Dr. Charles E. Bessey. The two species of dandelion which have been studied are respectively the Leontodon taraxacum and the L. erythrospermum of the Second Edition of Britton and Brown's Illustrated Flora: the nomenclature used in the title of this paper has been adopted on the basis of evidence presented in the monograph of the genus Taraxacum by Handel-Mazetti.

Evaporation And Plant Zones In The Cedar Point Marsh, Paul B. Sears

Papers in Ecology

Yapp in trying to account for the xerophytic structure of marsh plants by means of evaporation studies has shown a definite correlation to exist between the strata of marsh vegetation and rates of evaporation at corresponding levels. The following studies were made in an attempt to discover what additional correlations, if any, exist between distribution of marsh plants and the evaporational power of the air at different portions of the habitat. While the exact quantitative significance of such work as the following may be brought into question, as it often is, the striking results obtained by Transeau, Livingston, Fuller, Weaver, …

Natural Reforestation In The Mountains Of Northern Idaho, Harry B. Humphrey, John Ernst Weaver

Papers of John E. Weaver (1884–1956)

The factors affecting the natural reforestation of a fire-denuded area may, in general, be said to be the same in Idaho and Oregon as in Maine or Minnesota. There may be and actually are differences in detail as to what species of herbaceous and shrubby plants may prepare the way for the more delicate seedlings of those trees native to the particular locality. But the principle prevails everywhere that certain plants or plant societies. are antecedent and probably essential to the appearance and permanent establishment of a forest. The first step in the reforestation of a fire-swept area is the …

A Study Of The Root-Systems Of Prairie Plants Of Southeastern Washington, John Ernest Weaver

Papers of John E. Weaver (1884–1956)

While carrying on a study of the plant formations and associations of semi-arid southeastern Washington in 1912-1914, it soon became apparent that for a proper understanding of the development and structure of these associations a knowledge of the root-systems of the more important prairie species was imperative. Consequently, during the fall, winter, and spring of 1913--1914, more than 350 root-systems of 25 of the most important ecological species were examined. This paper contains descriptions of these, together with a discussion of the conditions under which the plants grow.

The prairies of southeastern Washington, and their eastward extension into adjacent Idaho, …

The Insect Galls Of Cedar Point And Vicinity, Paul B. Sears

Papers in Ecology

The following list is based on rather careful collections made during the summer of 1914. Since the list contains many forms common throughout Ohio, I have aimed to make the synonymy fairly complete to date, as an aid to students, while the bibliography has been limited to original description (where possible) and some more recent notice which should be helpful.

In the course of this work I have become deeply indebted to Mr. W. J. Kostir, of Ohio State University, while Prof. Herbert Osborn, Prof. B. W. Wells, Prof. Myron Swenk, Miss Edith Patch, Mr. Nathan Banks and others have …

The Phytogeography Of Nebraska, Roscoe Pound, Frederic E. Clements

Papers in Systematics and Biological Diversity

From the preface we learn that this work is the result of nearly five years of active study of the floral covering of Nebraska, carried on by the members of the Botanical Seminar in the Botanical Survey of the State of Nebraska. The systematic study of the vegetation of Nebraska was begun by Dr. Bessey in 1884, and has since been carried on by him and his students, all previous collecting having been more or less desultory and unreliable. The Botanical Survey was organized in 1892, and its work has been directed to the collecting of specimens and observations for …

A New Method For The Quantitative Determination Of Plankton Hauls, Henry B. Ward

Studies from the University of Nebraska Zoological Laboratory

Only two methods of estimating the quantity of plankton obtained in a haul of the vertical net are known to me. These two may be called the volumetric and the gravimetric. Both have been used by observers in various parts of the world, but so far as I know have never been comparatively tested in order to ascertain the relative value of results obtained by the two. The experience of the past year has shown some disadvantages in the first method, while the second has certain evident objections which rendered its employment in this case out of the question. In …

Evolution And Classification, Charles E. Bessey

Papers in Systematics and Biological Diversity

As we have gathered up the scattered masses of botanical knowledge, laboriously wrought out by many isolated workers, and attempted to fit them together into a consistent whole, which should outline the structure of the temple of botany, we have found that the workmen have not always followed the same architectural plan, and have often used different units of measurement. With the increasing specialization so noticeable year by year there is a corresponding lack of coordination of work. To this lack of coordination, this want of unity of measurement, this misunderstanding of plan, we can no longer close our eyes, …