Towards a simplified taxonomy of Capsella bursa-pastoris (L.) Medik. (Brassicaceae)

Capsella bursa-pastoris (L.) Medik. is a species with a cosmopolitan distribution which shows considerable morphological variation. Numerous authors have recognised widely differing numbers of varieties, microspecies or other infraspecific subdivisions (segregates) of this species. In an attempt to clarify this situation, we grew British material of the species under controlled conditions through to the F) generation to remove environmental variation, and assessed the plants on the basis of a range of morphological criteria, namely leaf shape, capsule size and also length of time taken to flower. Analysis of these characteristics consistently produced four basic groups, which had been previously described. Herbarium specimens could also nearly always be assigned to one of these groups. Limited chromosome counts suggest that two of these groups are diploid and two are tetraploid. We suggest this fourfold division into broad groups reflects the major genetic separations within the species, but that there is also considerable phenotypic plasticity shown by C. bursapastoris in response to factors such as shade or trampling. These four groups appear to differ in their geographic.al distribution in Britain. KEYWORDS: Shepherd's Purse, morphological variation, leaf characters, capsule characters, chromosom

Ten Years in Rehabilitation of Spoil: Appearance, Plant Colonists, and the Dominant Herbivore

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Relation of Certain Management Practices to Yields of Tobacco in Bradley County

[From the Introduction]This problem is a collateral study to one which has been completed on The Relation of Soil Type and Certain Chemical Soil Tests to Yields of Tobacco in Bradley County (2). Results of this study indicated a very strong positive correlation beween soil type and yield of tobacco. Nevertheless, the fact that so many low yields were produced on excellent and good soils pointed to a need for further study in an effort to account for some of these low yields on good soils. A study was thus made based on the following objective: to determine the relation of certain management practices to yields of tobacco in Bradley County

Restoring native plants following invasive Malephora Crocea (coppery iceplant, Aizoaceae) eradication on Anacapa Island

To avoid unintended complications of invasive species eradication, it is important to understand the potential implications of the techniques used in species eradication efforts. This study aimed to compare how different methods of removing Malephora crocea affect the survivorship of planted seedlings of native perennial plants on Anacapa Island. Employing a randomized complete block design in an M. crocea stand, three removal treatments were tested: 1) hand-pull; 2) spray with herbicide and leave skeletons; and 3) spray and then remove skeletons after 2.5 months. In each treatment, seedlings of three species (Leptosyne gigantea, Frankenia salina, and Grindelia stricta) and seeds of two species (L. gigantea and G. stricta) were planted. Survivorship and seed establishment were monitored quarterly between March 2010 and January 2011. For transplanted seedlings, the spray-and-leave treatment resulted in higher survivorship, while no difference was observed between the pull-treatments. Seed establishment was very low overall, but results of seeding of G. stricta showed that the spray-and-pull treatment provided for higher establishment than other treatments. L. gigantea seed establishment was inconclusive. The spray-and-leave treatment also provided the highest relative soil moisture. My results suggest that the spray-and-leave treatment provided the most suitable conditions for survival of transplanted native perennial vegetation

Studies on the biology of moorland Collembola

Work on the biology of Collembola (Springtails) was carried out betweenn Ootober 1959 and October I962, on the Moor House National Nature Reserve, in Westmorland. This is an area of high Pennine moorland (l840ft. O.D.) which experiences a sub-Arctic olimate. Population studies wars made on Limestone grassland, Alluvial grassland and Heather moor, by means of a statistical sampling method. Juncus squarrosus grassland and the erosion and recolonisation of blanket bog were also studied from the points of view of population densities and species differences. In an attempt to explain the fluctuations in numbers rocorded, biological data was also obtained from laboratory cultures of selected species. Observations on reproductive behaviour, fecundity, egg development, frequency of moulting, sex ratios and age distributions were made. Breeding experiments on members of the Onychiurus arnatus species group were carried out, and these revealed what appears to be an unusual form of parthenogenesis; these experiments also showed that in some species, at least, the criteria for the division of the 0. aimatus species group, which have been questioned by some continental workers, are valid. Regular sampling of the selected vegetation types provided data on horizontal distribution (aggregations), vertical distribution and seasonal variations in the numbers and biomass of Collembola. Limestone grassland carried the highest mean anual population density (52.92 x 10(^3) per m(^2)) and Juncus squarrosus grassland the lowest (20.93 x 10(^3) per m(^2)). A flotation extractor, to remove Collembola from organic soils, was designed and built, and this may prove an important step forward in the technique of studying the moorland fauna. The work forms a contribution to the study of moorland ecology, but it is clear that to obtain a comprehensive picture of the ecological importance of Collembola on moorland, a great deal of work will be necessary in the future