ECOLOGICAL STUDY OF THE PEAT BOGS OF EASTERN NORTH AMERICA: I. STRUCTURE AND EVOLUTION OF VEGETATION

1952 ◽  
Vol 30 (4) ◽  
pp. 490-520 ◽  
Author(s):  
Pierre Dansereau ◽  
Fernando Segadas-Vianna

It is attempted to clearly distinguish between bogs on the one hand and swamps and marshes on the other. The principal elements and factors are listed in Eastern North America where bogs are frequent. This first paper attempts a general outline of the dynamics of bog vegetation in this region and describes the structures of the communities involved. The biotope is considered the smallest piece in the association mosaic and its physical and biological aspects are emphasized. Two recent systems (Küchler's and Dansereau's) are applied to individualize the most important and widespread synecological units. Further studies involving climatic relationships on a geographical scale and phytosociological measurements at the quadrat level will permit a refocusing of some of the phenomena which are described and interpreted here.

1956 ◽  
Vol 34 (1) ◽  
pp. 197-207 ◽  
Author(s):  
Kornelius Lems

This paper presents data and observations concerning Chamaedaphne calyculata (L.) Moench. (Ericaceae). The branching pattern, the longevity of different types of leaves, and features of flowering are shown to be correlated. The relationship between this complex of features and the habitat is studied, and a few speculations are advanced to explain the physiological basis for the behavior of Chamaedaphne. This study is essentially autecological, and it is hoped that it may constitute a link between the study of soil conditions and the response of plant hormones on the one hand, and phytosociological work in peat bogs on the other hand.


1955 ◽  
Vol 33 (6) ◽  
pp. 647-684 ◽  
Author(s):  
Fernando Segadas-Vianna

Data collected in this very uniform bog community lend themselves particularly well to an assessment of phytosociological criteria. Expressions of frequency, constancy, fidelity, homogeneity as proposed by various writers are tested and evaluated. At the same time, it is believed that the present paper provides an accurate description and definition of the phytosociological unit with which it is concerned.


2019 ◽  
Vol 59 (2) ◽  
pp. 229-239 ◽  
Author(s):  
Else Marie Friis ◽  
Peter R. Crane ◽  
Kaj Raunsgaard Pedersen

Abstract A new genus and species, Geminispermum virginiense, is described based on a well-preserved coalified cupulate reproductive unit recovered from the Early Cretaceous (early–middle Albian) Puddledock locality, Virginia, U.S.A. The reproductive unit is bisymmetrical and consists of an axis that bifurcates into two cupule-bearing stalks, each in the axil of a bract. Each cupule stalk bears a single non-valvate cupule recurved towards the center of the reproductive unit. The cupule opens distally by a short transverse slit with a distinct upper margin. Each cupule almost completely encloses a single orthotropous seed that is free from the cupule except at the base. The nucellus is also free from the integument except at the basal point of attachment. Geminispermum combines features of the ovulate structures of Caytoniales, Umkomasiales (= Corystospermales, including Doyleales) and Petriellales, but cannot be included in any of these existing orders as they are currently understood. The recurved, closed, non-valvate cupules are particularly similar to those of Caytonia, Petriellaea and Reymanownaea in external morphology, but differ in being one-seeded. The cupules of Geminispermum differ from the one-seeded cupules of Umkomasiales in being non-valvate and in having only a single cupule per bract. Geminispermum is perhaps most similar to the one- or two-seeded non-valvate cupules of Ktalenia from the Early Cretaceous of Argentina, but Ktalenia is poorly preserved, details of cupule architecture are uncertain, and the cupules appear to be associated with a single strongly dissected bract. Geminispermum is currently the only unequivocal seed plant cupule recovered from the Early Cretaceous Potomac Group and is distinct from all previously described cupulate reproductive structures.


1971 ◽  
Vol 103 (11) ◽  
pp. 1557-1590 ◽  
Author(s):  
E. E. Lindquist ◽  
P. H. Vercammen-Grandjean

AbstractThe trombidiid subfamily Neotrombidiinae Feider is re-established and redefined, based primarily on larval characters but also on adult characters. It is closely related to the trombidiid Trombellinae on the one hand and to the Leeuwenhoekidae on the other. It consists of two genera, namely Monunguis Wharton, which is monobasic and known only from the larva, and Neotrombidium Leonardi, with 13 described species of which 7 are known from the larva and 8 from the adult (the larva and adult of 2 species are correlated by rearings).The history of the family-level placement of this group, and the controversy over whether or not to recognize two genera, are reviewed. The characters that justify the separate recognition of Monunguis and Neotrombidium are enumerated.The larva of each of the following species of Neotrombidiinae is described, illustrated and keyed: Monunguis streblida Wharton from the Caribbean area, Neotrombidium barringunense Hirst from Australia, N. tricuspidum Borland from North America, N. tenuipes (Womersley) from Malaya, N. samsinaki (Daniel) new combination from central Europe, N. anuroporum new species from Central America, N. bengalense new species from India, and N. tenebrione new species from eastern North America. Six other species of this group, known only from the adult, are listed separately but are not treated taxonomically here.The larvae of Neotrombidiinae parasitize adult insects: those of Monunguis are hyperparasites on streblid flies whereas those of Neotrombidium are ectoparasites of cerambycid, clerid, elaterid, and tenebrionid beetles that pass part of their life history under the bark of trees.In the Microtrombidiinae, Camerotrombidium Thor is noted as the valid replacement name for the preoccupied Ottonia Kramer.


2015 ◽  
Vol 89 (6) ◽  
pp. 1082-1088
Author(s):  
Steven E. Jasinski ◽  
Steven C. Wallace

AbstractA tooth recovered from the middle Miocene Choptank Formation (Chesapeake Group) of Maryland is identified as a new cynarctin borophagine (Canidae: Borophaginae: Cynarctina), here called Cynarctus wangi n. sp. The tooth, identified as a right upper second molar, represents the first carnivoran material reported from the Choptank Formation and part of a limited record of borophagine canids from eastern North America. As ?Cynarctus marylandica (Berry, 1938), another cynarctin borophagine from the older Calvert Formation, is known only from lower dentition, its generic affinities are uncertain. However, features of this new material are compared to features of ?C. marylandica through occlusal relationships, allowing for referral to a distinct species. Even so, the Choptank Formation material still offers two possible scenarios regarding its identification. In one, its geographic and stratigraphic provenance could imply that it belongs to ?C. marylandica. If this were correct, then the generic placement of ?C. marylandica would be correct and the taxon would be more derived than some other Cynarctus species in regard to hypocarnivory, and less derived than others. The second possibility, and the one believed to be most probable, is that a distinct cynarctin borophagine is present in the Chesapeake Group in strata younger than the type specimen of ?C. marylandica. This new borophagine canid expands the sparse fossil record of this group in northeastern North America and furthers our knowledge of the fossil record of terrestrial taxa in this region.


1986 ◽  
Vol 6 (3) ◽  
pp. 227-243 ◽  
Author(s):  
Andrew L. Christenson

Although the interest in shell middens in North America is often traced to reports of the discoveries in Danish kjoekkenmoeddings in the mid-nineteenth century, extensive shell midden studies were already occurring on the East Coast by that time. This article reviews selected examples of this early work done by geologists and naturalists, which served as a foundation for shell midden studies by archaeologists after the Civil War.


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