The taxonomic history of 17 British and N. W. European taxa of the Festuca ovina aggregate was reviewed. The morphology, anatomy, ecology, geographical distribution and typification of F. ovina, F. guestfalica, F. vivipara, F. lemanii, F. trachyphylla and F. brevipila was also discussed. Anatomical characters were taken from leaf-blade transverse sections and from leaf-blade epidermises and proved useful at all taxonomic ranks investigated. Gross morphological characters were generally slightly less useful although floral morphology was of great use at and below specific rank. Reliability of these characters has been assessed in cultivatio-n experiments. On the basis of morphological, anatomical, cytological, chemical and geographical evidence and with the aid of multivariant analysis and extensive hybridization studies it is concluded that the taxa studied fall into 3 species groups: the F. ovina group; the F. valesiaca group and the F. longifolia group. Hybridization at the hexaploid level more frequently produced more mature FI hybrids than did hybridizations at the tetraploid level. Hybridizations between diploid species produced the lowest numbers of mature FI hybrids. Furthermore diploid taxa were found to be more discrete morphologically than tetraploid taxa which were in turn more discrete than hexaploid taxa. It was concluded from this that the F. ovina aggregate is a polyploid pillar complex. On the basis of a wide body of evidence it was concluded that F. vivipara undoubtedly belongs to the F. ovina species group. The evolutionary relationship between this taxon with its close seminiferous relatives was also discussed.

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Introduced cool-season grasses are dominant in Virginia's grasslands, but their high digestible energy and non-structural carbohydrate (NSC) levels pose a risk for horses prone to obesity and laminitis. Native warm-season grasses (NWSG) have lower digestible energy and NSC levels that may be more suitable for horses susceptible to laminitis. The overall objectives of this research were to 1) assess voluntary intake, toxicological response, and apparent digestibility of NWSG hays fed to horses; 2) evaluate the characteristics of three NWSG species under equine grazing; and 3) evaluate establishment strategies for NWSG and wildflowers in Virginia. For the first objective, a hay feeding trial was conducted with 9 Thoroughbred geldings in a 3 x 3 Latin square design. Voluntary dry matter intake of indiangrass (Sorghastrum nutans) and big bluestem (Andropogon gerardii) hays by horses were 1.3% and 1.1% of BW/d, significantly lower than orchardgrass (Dactylis glomerata), an introduced cool-season grass, at 1.7% of BW/d. Biomarkers for toxicity remained within acceptable ranges for all treatments. Apparent DMD did not differ among hays, ranging from 39 to 43%. Non-structural carbohydrate levels were below the maximum recommended concentration for horses susceptible to laminitis. For the second objective, a grazing trial was conducted comparing indiangrass (IG), big bluestem (BB), and eastern gamagrass (Tripsacum dactyloides) (EG) yields, forage losses, changes in vegetative composition, and effects on equine bodyweight. Nine, 0.1-hectare plots were seeded with one of the three native grass treatments, and each plot was grazed by one Thoroughbred gelding in two grazing bouts, one in July and another in September 2019. Indiangrass had the highest available forage, at 4340 kg/ha, compared with 3590 kg/ha from BB (P < 0.0001). Eastern gamagrass plots established poorly, and had only 650 kg/ha available forage during the experiment. Grazing reduced standing cover of native grasses in IG and BB treatments by about 30%, and trampled forage constituted 36-68% of groundcover in those plots after each grazing bout. Horses lost weight on all treatments, but tended (P=0.09) greater weight loss on the indiangrass treatment at 1.5 kg/d compared to 0.5 kg/d in the BB and EG treatments. For the third objective, three experiments were conducted to evaluate different strategies for establishing NWSG and wildflowers. The first experiment compared large grazed plots with or without a 2 oz/acre rate of the herbicide imazapic. Imazapic led to higher biomass and percent cover in plots seeded only with NWSG. For plots seeded with a mix of NWSG and wildflowers, imazapic reduced wildflower establishment and resulted in higher biomass and percent cover of weeds over the course of the experiment. The second experiment examined four rates of imazapic application for NWSG and wildflower establishment in small plots seeded with either NWSG or a NWSG and wildflower mix, and found biomass and percent cover of weeds was lowest at a 6 oz/acre rate, while NWSG biomass and cover did not differ between treatments. Wildflower establishment was again reduced by imazapic. The third establishment experiment compared four site preparation strategies for wildflower establishment and found tillage resulted in the most cover and biomass of wildflowers. / Doctor of Philosophy / Introduced cool-season grasses are dominant in Virginia's grasslands, but their high digestible energy and non-structural carbohydrate (NSC) levels pose a risk for horses prone to obesity and laminitis. Native warm-season grasses (NWSG) have lower digestible energy and NSC levels that may be more suitable for horses susceptible to laminitis. The overall objectives of this research were to 1) assess voluntary intake, toxicological response, and apparent digestibility of NWSG hays fed to horses; 2) evaluate the characteristics of three NWSG species under equine grazing; and 3) evaluate establishment strategies for NWSG and wildflowers in Virginia. For the first objective, a hay feeding trial was conducted with 9 Thoroughbred geldings in a 3 x 3 Latin square design. Voluntary dry matter intake of indiangrass (Sorghastrum nutans) and big bluestem (Andropogon gerardii) hays by horses were 1.3% and 1.1% of BW/d, significantly lower than orchardgrass (Dactylis glomerata), an introduced cool-season grass, at 1.7% of BW/d. Biomarkers for toxicity remained within acceptable ranges for all treatments. Apparent DMD did not differ among hays, ranging from 39 to 43%. Non-structural carbohydrate levels were below the maximum recommended concentration for horses susceptible to laminitis. For the second objective, a grazing trial was conducted comparing indiangrass (IG), big bluestem (BB), and eastern gamagrass (Tripsacum dactyloides) (EG) yields, forage losses, changes in vegetative composition, and effects on equine bodyweight. Nine, 0.1-hectare plots were seeded with one of the three native grass treatments, and each plot was grazed by one Thoroughbred gelding in two grazing bouts, one in July and another in September 2019. Indiangrass had the highest available forage, at 4340 kg/ha, compared with 3590 kg/ha from BB (P < 0.0001). Eastern gamagrass plots established poorly, and had only 650 kg/ha available forage during the experiment. Grazing reduced standing cover of native grasses in IG and BB treatments by about 30%, and trampled forage constituted 36-68% of groundcover in those plots after each grazing bout. Horses lost weight on all treatments, but tended (P=0.09) greater weight loss on the indiangrass treatment at 1.5 kg/d compared to 0.5 kg/d in the BB and EG treatments. For the third objective, three experiments were conducted to evaluate different strategies for establishing NWSG and wildflowers. The first experiment compared large grazed plots with or without a 2 oz/acre rate of the herbicide imazapic. Imazapic led to higher biomass and percent cover in plots seeded only with NWSG. For plots seeded with a mix of NWSG and wildflowers, imazapic reduced wildflower establishment and resulted in higher biomass and percent cover of weeds over the course of the experiment. The second experiment examined four rates of imazapic application for NWSG and wildflower establishment in small plots seeded with either NWSG or a NWSG and wildflower mix, and found biomass and percent cover of weeds was lowest at a 6 oz/acre rate, while NWSG biomass and cover did not differ between treatments. Wildflower establishment was again reduced by imazapic. The third establishment experiment compared four site preparation strategies for wildflower establishment and found tillage resulted in the most cover and biomass of wildflowers.

Thesis--Würzburg. / Vita. Includes bibliographical references (p. 159-163).

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Zugl.: Tübingen, Univ., Diss., 2005

Zugl.: Stockholm, Universiẗat, Diss., 2004.