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American material of Festuca brachyphylla Schult. & Schult., F. saximontana Rydb. and related species was studied. Based on morphology and anatomy F. brachyphylla was separated into three subspecies, two of which are only found in very restricted areas of the southern part of North America, one in California (ssp. breviculmis Frederiksen ssp. nov.) and one in Colorado and neighbouring states (ssp. coloraden–sis Frederiksen ssp. nov.). F. jenseni Gjaerevoll & Ryvarden was found to be the same as F. brachyphylla i.flavida Polun. and the forma level is chosen. F. brachyphylla var. groenlandica Schol. is raised to F. groenlandica (Schol.) Frederiksen. Within F. saximontana a new combination (f. saximontana Rydb. var. purpusiana Frederiksen & Pavlick) is made. American distribution of the taxa studied is mapped. A key including all the taxa has been prepared.  相似文献   

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North America     
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The study of prehistoric parasitism through analysis of coprolites, mummies, skeletons, and latrine soils is rapidly growing. Its development in North America is interdisciplinary and is derived from the fields of physical anthropology, parasitology, and archaeology. The various parasite finds from North America are reviewed. The data show that prehistoric peoples in North America suffered from a variety of parasitic diseases. The validity of the findings are then considered. Although most finds of parasites from prehistoric contexts result from human infections, some finds cannot be verified as such. However, in combination with data from South America, it is clear that prehistoric peoples in the Americas were host to a variety of human parasites, some of which were not previously thought to be present before historic times.  相似文献   

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《Plains anthropologist》2013,58(18):232-236
Abstract

Basic data are offered on 2 pottery bearing localities in the Souris Basin, North Dakota. Additional data from adjacent areas are introduced to support the assertion that there was a relatively heavy occupation of the Northern Plains by a number of closely related groups which manufactured only slightly differentiated cordroughened pottery. The presence of this pottery reveals that the Woodland occupation of the Northern Plains was far more intensive and extensive than might be suspected from the extant literature.  相似文献   

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Viviparous Festuca especially from the North Atlantic area have been examined. Based on especially the chromosome numbers they are divided into three subspecies and a number of hybrids: 1) F. vivipara (L.) Sm. ssp. vivipara , 2) F. vivipara ssp. hirsuta (Schol.) Frederiksen stat. nov., 3) F. vivipara ssp. glabra Frederiksen ssp. nov. Hybrids between F. vivipara on the one hand and F. rubra L. or F. ovina L. on the other were found to be common.  相似文献   

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Ethnohistorically, wild and domesticated teparies (Phaseolus acutifolius: Leguminosae) are significant native food crops in southwestern North America. Their value rests in adaptations to arid environments, and high protein content and productivity. Use of wild teparies appears to be discontinued, but certain domesticated varieties are still grown by local commercial and subsistence farmers. The recent subsidence of tepary cultivation is related to breakdown of traditional economies and land use, and to the introduction of energy-intensive irrigated agriculture. An earlier and unsuccessful attempt to introduce teparies into modern agriculture was poorly timed. Teparies have considerable potential for low maintenance agriculture in arid and semi-arid lands.  相似文献   

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The forests of North America provide a variety of benefits including water, recreation, wildlife habitat, timber, and other forest products. However, they continue to face many biotic and abiotic stressors including fires, native and invasive pests, fragmentation, and air pollution. Forest health specialists have been monitoring the health of forests for many years. This paper highlights some of the most damaging forest stressors affecting North American forests in recent years and provides some projections of future risks.  相似文献   

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