Davidsonia

An index of authors, titles, illustrations and keywords for Davidsonia Volume 14.

Davidsonia - A Journal of Botanical Garden Science. Volume 14, Number 4, October 2003

Editor Iain Taylor writes about the importance of studying the small scale ecological systems, which occur in British Columbia and the importance of these fragmented environments to the biodiversity of the province.

The variety and widespread nature of leaf colour change in autumn has led to investigation of the biochemical pathways and compounds responsible. The synthesis of bright red colouration initiated by longer nights prior to leaf abscission in deciduous species points to some adaptive value for this expensive ephemeral trait. It is hypothesized that during the breakdown of the unstable chlorophyll and the dismantling of the nutrient-rich photosynthetic apparatus, red anthocyanins provide a more biochemically parsimonious alternative to the elaborate xanthophyll system. This alternative enables leaves to screen out excess light energy and circumvent photooxidative damage to leaf cells, while allowing photosynthesis to persist at low rates in support of metabolic processes and phloem loading required for nutrient resorption from leaves.

While distinct floristic and ecological patterns have been reported for ultramafic (serpentine) sites in California and Oregon, those of British Columbia are muted which is thought to be related to the moderating influence of increased precipitation, a short time since glaciation, and the presence of non-ultramafic glacial till over ultramafic sites. Despite these factors, we found clear floristic and ecological differences with respect to soil type at our study site on Grasshopper Mountain, part of the Tulameen ultramafic complex in southern British Columbia. Ultramafic soils support 28% of the local species richness and host more rare taxa than non-ultramafic soils. Many species show patterns of local restriction to or exclusion from ultramafic soil habitats. Patterns of plant family diversity also show differences between substrates.

Rubus idaeus L., the red raspberry consists of two subspecies, R. idaeus subsp. strigosus Michx, which is native to North America and far eastern Asia, and R. idaeus subsp. vulgatus Arrhen, which is native to Europe and Asia Minor. The subspecies are usually referred to as R. strigosus and R. idaeus, respectively. Neither is adequately represented in the red raspberry breeding gene pool. This paper describes efforts to find potentially useful parents with disease or insect resistances from previously unexploited selections of R. strigosus. Selections with resistances to aphid, root rots, and cane diseases were identified and have been incorporated into the Pacific Agriculture Research Centre’s breeding programme. Several derivatives of the selections have the potential to become cultivars with entirely new sources of resistances.

The November installment of Judy Newton's popular series describing what to see at the UBC Botanical Garden each month of the year.

The Editors of Davidsonia highlight some of the most interesting and important titles from the thousands of recently published papers in the plant sciences.

Davidsonia - A Journal of Botanical Garden Science. Volume 14, Number 3, July 2003.

Editor, Iain Taylor writes about the importance of peer review in science journals.