Davidsonia - Volume 17

Davidsonia Volume 17, Number 4, October 2006

Mon, 11 Jun 2007 15:36:02 -0700

Abstract or Summary:

A Journal of Botanical Garden Science.

Editorial - Davidsonia Volume 17, Number 4

Mon, 11 Jun 2007 15:32:38 -0700

Abstract or Summary:

Editor, Iain Taylor shares his views on the progress of the journal and its potential future.

Embryological and Phenological Comparison between Arceuthobium americanum (the lodgepole pine dwarf mistletoe) growing on ...

Mon, 11 Jun 2007 15:17:08 -0700

Abstract or Summary:

The genus Arceuthobium comprises angiosperms that are aerial parasites on Pinaceae and Cupressaceae. These parasites are serious forest pests in North America, where they damage timber trees. In Canada, Arceuthobium americanum (the lodgepole pine dwarf mistletoe) is principally found on Pinus contorta var. latifolia (lodgepole pine) in British Columbia (BC) and Alberta as well as on Pinus banksiana (jack pine) in Alberta, Saskatchewan and Manitoba. Although widespread, A. americanum seems morphologically uniform in its range. However, the taxon has been divided into two distinct genetic races based on the variation observed in amplified fragment length polymorphism (AFLP) data. This led us to predict that there would be some variation in anatomical, as opposed to external morphological form. Therefore, the objective of this study was to determine if the embryological anatomy of A. americanum growing on P. contorta var. latifolia in BC differed from that growing on P. banksiana in Manitoba. Samples of female flowers were collected from both BC and Manitoba throughout the growing season and prepared for routine light microscopy. Key embryological stages were observed, and the relative timing of these stages were compared between the BC and Manitoba collections. Our results were in direct contrast with our prediction, which had to be falsified: hundreds of prepared sections revealed that major embryological events, including double fertilization and zygotic division, are indistinguishable and occur at essentially the same time. This first study on emrbyology of two plants growing on the two pine speces at the extreme geographic ranges shows that the development is similar. Despite climate, host, ecology, and geography, which remain variables of undetermined relative significance, the mechanism for embryological development is likely highly conserved for A. americanum across Canada.

Evergreen Magnolias Growing at UBC Botanical Garden, Vancouver, Canada: a Progress Report

Mon, 11 Jun 2007 14:58:30 -0700

Abstract or Summary:

Southeast Asia is home to many evergreen magnolia varieties. Peter Wharton, curator of the David C. Lam Asian Garden at UBC Botanical Garden, writes about some of the evergreen magnolias growing at the garden. Peter describes the growth and cultural habits of some of these trees, which hold promise for landscapes in the Pacific Northwest of North America and other areas.

Gleanings - Davidsonia Volume 17, Number 4

Mon, 11 Jun 2007 14:42:19 -0700

Abstract or Summary:

The editor comments on three papers that caught his eye this issue, with topics of climate and crop yields, restoration of forest areas attacked by the mountain pine beetle, and the 75^th Anniversary of the Canadian Society of Plant Pathologist.

Volume 17 Index

Mon, 11 Jun 2007 14:39:39 -0700

Abstract or Summary:

An index to authors titles, illustrations and key words for Davidsonia Volume 17.

Davidsonia Volume 17, Number 3, July 2006

Fri, 02 Mar 2007 13:47:09 -0800

Abstract or Summary:

A Journal of Botanical Garden Science

Editorial - Davidsonia Volume 17, Number 3

Fri, 02 Mar 2007 13:42:44 -0800

Abstract or Summary:

Editor Iain Taylor writes on the difficulties faced by botanists and ecologist in getting their research supported and published.

Comparison of Two Garry Oak Sites Undergoing Restoration on Southeastern Vancouver Island: a Preliminary Study

Fri, 02 Mar 2007 13:25:33 -0800

Abstract or Summary:

Garry oak ecosystems represent unique species-rich communities in the Pacific Northwest United States and southwestern Canada. These distinct ecosystems are becoming rare as their integrity is threatened by urban and agricultural encroachments, as well as by the introduction of non-native plant taxa. We visited two Garry oak parklands, one that had been heavily impacted until recently by grazing cattle, and one that has been protected from such anthropogenic activities for several years and currently has an active restoration program. We compared the quantitative occurrence and compositional variation of six regionally common plant species between these two sites using univariate and multivariate statistical methods. Our results showed clear differences in the quantitative patterns of abundance and overall variation among species between the two sites. These results indicate that the restoration efforts at Site 2 have promoted greater coverage of native species and greater community variation, both considered to be positive indicators of biodiversity for this ecosystem.

Book Reviews - Davidsonia Volume 17, Number 3

Fri, 02 Mar 2007 13:13:11 -0800

Abstract or Summary:

Flowering and its Manipulation, edited by Charles Ainsworth, and Biology of the Plant Cuticle, edited by Markus Riederer and Caroline Müller are reviewed.

Gleanings - Davidsonia Volume 17, Number 3

Fri, 02 Mar 2007 12:52:52 -0800

Abstract or Summary:

The Editor's notes on papers (some technical and others less so) that may be of interest.

Davidsonia Volume 17, Number 2, April 2006

Tue, 28 Nov 2006 14:50:39 -0800

Abstract or Summary:

Davidsonia - A Journal of Botanical Garden Science

Editorial - Davidsonia Volume 17, Number 2

Tue, 28 Nov 2006 13:57:41 -0800

Abstract or Summary:

Editor, Iain Taylor looks at current issues of the botanical world.

Historical Garry Oak Ecosystems of Vancouver Island, British Columbia, pre-European Contact to the Present

Tue, 28 Nov 2006 13:49:23 -0800

Abstract or Summary:

This paper summarizes the historical mapping of the major areas of Quercus garryana (Garry oak) ecosystems, from immediate pre-European settlement to present day. Less than 10 percent of the original Garry oak ecosystem remains on south-eastern Vancouver Island, British Columbia, Canada. Originally, there were two major ecosystem types, one on deep soils, known as Parkland Garry oak ecosystems, and the second on shallow soils, often referred to as scrub oak ecosystems because the oak trees are often of low stature. Little of the deep soil ecosystem remains, because these communities were the first areas cleared for agriculture and urban development. More of the shallow soil ecosystem remains, as many of these rocky areas were more difficult to develop in the early days of settlement and were not good for agriculture. However, many of these sites are presently being lost to development if they are not in protected areas. Much of the remaining area of these ecosystems is dominated by invasive alien plant species, so that less than 5 percent of the original area remains in natural condition.

The Vascular Plant Flora of the South Puget Sound Prairies, Washington, USA

Tue, 28 Nov 2006 13:26:55 -0800

Abstract or Summary:

Vascular plant species lists were compiled for all the major prairies that remain in south Puget Sound, Washington State, USA. Overall, 278 species were recorded in 15 prairies that ranged in area from 12-3,000 ha. Fifty-nine percent of these were native taxa, with forbs the most frequently represented life form (74%). Seventy percent of the species were perennials. Annuals were most common in Ft. Lewis prairies, which may reflect higher levels of disturbance. On average, introduced annuals outnumbered the native annuals 2:1. Twenty-three native species were widespread, occurring in >80% of the prairies; all but one of these were perennial. In contrast, 5 of the 18 most widespread non-natives were annuals. Forty percent (64) of the native species were found in only 1 or 2 prairies, and another 61 prairie species were documented from a variety of sources as formerly or currently growing in the south Puget Sound region, but not currently known from the 15 prairies we studied. Our results provide a basis for identifying species potentially appropriate for including in prairie restoration efforts in this region. Our findings also suggest taxa that are uncommon, rare, or locally extirpated, and which may only persist in this region if active efforts are made to establish them in extant sites.