| BEN |
| BOTANICAL ELECTRONIC NEWS |
|---|
| ISSN 1188-603X |
| No. 195 June 6, 1998 | aceska@victoria.tc.ca Victoria, B.C. |
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The flora of Great Britain is depauperate compared to that of the nearby continent. The landbridge, which connected England to the Continent after the last glaciation, was cut off before most species had reached Northern France. Many British species failed to reach Ireland as the connection between Ireland and Great Britain disappeared even earlier. The European plant species richness, and that of woody plants in particular, is in turn lower than that found in North America. Although the climatic zonation of Europe is broadly similar to that of North America, the geographical position of mountain ranges and large water bodies is markedly different. The Alps and the Mediterranean sea run East to West and have, during the Quaternary period, hindered plant migration during the various phases of glacial expansions and contractions.
In Europe plant species have been translocated for thousands of years. However, species introductions have only markedly increased during the 17th century and peaked in the 19th century when the botanical exploration of Asia and the America's was at its peak. During this period, thousands of species were introduced and today over 3600 alien taxa are thought to be naturalized in Europe (Clement & Foster 1994, Ryves et al. 1996). Of course, only a small proportion of these taxa have had much of an impact on the native vegetation and most species have only been found regenerating very locally in highly disturbed urban or semi-natural areas. However, there are a number of shrubby species and coniferous trees spreading into semi-natural vegetation. These life-forms are not well represented in the indigenous flora of the British Isles. There is only one large conifer (Pinus sylvestris, native to Scotland) and a few shrubby species that usually form a sparse growth under woodland canopies.
Many of the introduced shrub and coniferous species in the British Isles originated from North America, and the Pacific Northwest in particular. They have been introduced for a variety of reasons including for ornament, shelter for game and forestry. These species are well suited to the climate of the British Isles and they are particularly successful on the western side of Great Britain and Ireland where rainfall is high and winters are mild.
Some North American woody plant species have become invasive in most parts of Europe; these include Acer negundo (Sachse 1992), Prunus serotina (Starfinger 1997), Quercus rubra (Barkman 1988, Timbal 1994), and Robinia pseudoacacia (Kowarik 1990) which occur now in natural and semi-natural vegetation of continental Europe. Several Pacific Northwest species are spreading in more oceanic regions and the main ones are described in more detail below.
The taxonomic nature of Amelanchier species in western Europe has been much debated. Schroeder (1970, 1972) concluded that three North America species, Amelanchier confusa, A. lamarckii and A. spicata, are fully naturalized in western Europe, the latter two species being commonly found from England to Sweden. Amelanchier alnifolia, which was planted in 19th century parks, is no longer cultivated, but is naturalized in a couple of localities.
This shrub is only known to be invasive in north-east England (Swan 1993), although it is found in many parts of the British Isles. Currently, it is a pest at only one site, where it forms monotypic stands and spreads into heathland.
This species, recognized as weedy in North America (Fraser et al. 1993), exhibits similar characteristics in NE England where it readily regenerate in areas cleared of other woody invaders such as Rhododendron ponticum (a native of SE Europe and probably the worst invader in the British Isles). It is as yet unclear how much of a threat Gaultheria shallon is in the British Isles.
Salmonberry was brought to the British Isles in 1827 and it said that it was introduced to Scotland as pheasant food. It has also been planted as an ornamental or as a hedge plant. The shrub is widespread and weedy in the Orkneys (Bremner & Bullard 1990) but its spread into other parts of the British Isles has been slow and largely unrecognized. Our recent investigations in Northern Ireland (Paterson & Binggeli 1995) showed that R. spectabilis produces large impenetrable thickets in a wide variety of vegetation types. It must be considered as a potential pest in forestry plantations in the north-west of Ireland.
At the start of the 20th century little of the original forest cover of the British Isles remained and an extensive afforestation program was initiated. At first, several conifer species were planted in monotypic stands, but in more recent decades most of the planting has been Sitka spruce. Early Sitka spruce plantations have already been felled and extensive natural regeneration has been observed with seedling densities as high as 300,000 per ha (McNeill & Thompson 1982, Clarke 1992, Ow et al. 1996). This regeneration is generally not welcomed by foresters as it is very uneven and increases the cost of silvicultural operations (Nelson 1991).
Symphoricarpos albus var. laevigatus is widely naturalized in western Europe. In the British Isles, the species was introduced in 1817 first as an horticultural plant, but was later grown as a component of game coverts. It has been recorded from a wide variety of soil and vegetation types, but it does not spread rapidly since local birds do not eat the fruits (Bremner & Bullard 1990, Gilbert 1995). The recent publication of an ecological account in the Journal of Ecology reflects the importance of Symphoricarpos albus in the British and Irish landscapes.
This tree has been planted in many parts of the British Isles, but it is not an important timber tree. However, it has regenerated in many places and can spread into semi-natural vegetation (Baker 1990).
A combination of the factors outlined above (i.e. depauperate flora, absence of some life-forms, and great similarity in climatic conditions) largely explain the successful establishment of Pacific Northwest plants in western Europe and the British Isles in particular. References
Three cheers and one cheer more (as they do it in Sweden) to my old friend Ted Mosquin for his brilliant elucidation of the pollination of Chamaepericlymenum canadense! It is, as he says, more evidence to support the generic recognition of this little genus. I have been using this name in my various Colorado floras ever since Askell Love and Josef Holub convinced me as to the justified separation of Cornus, Chamaepericlymenum, and Swida. I am gratified that some of the usually very conservative authors from the United States are beginning to catch on: Pentaphylloides (Rosaceae) is finally given the blessings of the authors of Intermountain Flora; Noccaea (Brassicaceae) is nearing universal support over its former inclusion in Thlaspi; Boechera out of Arabis. Who knows, perhaps they will eventually come to their senses and recognize Pulsatilla as distinct from Anemone! And, horror of horrors, perhaps someone else will support me and Eurasian authors on Sabina vs Juniperus, and break down the wastebasket genus Prunus into its other generic components, Padus, Cerasus, Amygdalus, and Laurocerasus; Rubus into Rubacer, Cylactis, and Oreobatus; Potentilla into not only Pentaphylloides, but Argentina, Comarum, Drymocallis; Geum into Acomastylis and Erythrocoma; and Ranunculus into Ceratocephala, Halerpestes, Hecatonia, and Cyrtorhyncha.
This book is the newest addition to the plant field guides published by the Lone Pine Publishing. See BEN #31, #75, #114, #132, #137, & Taxon 45:159-161 for reviews of other volumes published in this popular series. The book covers over 1200 species and is fully illustrated with colour photographs and line drawings.
Dr. W.A. Weber sent me the following comments:
I have the book, and it is really a remarkable one. I wish I had had the luxury of having a number of people involved in designing, editing, etc. on my books. There is an absolutely extraordinary amount of interesting reading in it. Of course, when you do as massive color production like this is, there will be a number of pictures that are too dark to be of any use, and the pictures sometimes are too small to get any detail. The book also is mostly for the Canadian Rocky Mts., and not of very great use down here. I understand very well the pressure to make the title more inclusive than the contents, as I learned when my little book of 1952, Plants of the Colorado Front Range, had to be changed to Rocky Mountain Flora although there was little expansion of the text.I think the authors go overboard telling people never to pick a flower even to examine it; people don't drive out and bring home carloads of wild flowers these days; that might have been true 50 years ago. Here around Boulder the problem is that we have so many deer and elk around that they do much more damage, even to people's gardens, than any number of human pickers.
I also am getting more and more frustrated by these people who have to invent "common names" for every species of everything. They certainly are no more "meaningful" than the scientific names, but for some reason they are comforting to those who need to put some kind of a name on a plant, just as nobody is happy with a mountain that has no name.
I have to say that the authors treated scientific names of plants much worse than the common names. There are numerous mistakes in the gender of Latin names: Comarum palustris, Nuphar lutea (feminine) & Nuphar polysepalum (neuter), Triglochin maritima (feminine) & Triglochin palustre (neuter). Ranunculus aquatilus? I have been soliciting a short course of botanical Latin and I hope that BEN will be able to devote one or two issues to that topic in the near future.
This book is an excellent edition to the botanical literature that deals with the Rocky Mountains.
This book is a result of co-operation of three agencies, the California Native Plant Society, the California Department of Fish and Game and the California Academy of Sciences:
"Within this book you will be introduced to the beauty and variety of California's native plants in their natural settings. California's Wild Gardens allows us to view California as a series of ecological regions ... Within these regions are smaller localized areas, where local conditions have bestowed a special ensemble of rare or endemic plants. These highlights of California's botanical world are the focus of this book -- a compendium of some of the best and most floristically important sites in our state."
About 100 botanists and plant ecologists worked on this book. The book gives descriptions of about a hundred important localities grouped in ten ecological regions. Each locality is illustrated with a general habitat picture and with a selection of colour photographs of the most important rare plants growing on that particular locality. All pictures are of the highest quality. The first time I saw a photograph of the recently discovered Shasta snow-wreath, Neviusia cliftonii. I was sorry to see a picture of Utricularia macrorhiza identified as U. gibba and I hope that the authors did not use my Madrono 1973 key to the genus Utricularia.
This is a beautiful book, highly recommended!
Term position reports to the Manager of Natural History. Duties include research and collection projects; field collections in the Columbia Basin focussing on the non-grassland habitats; extensive travel within southern B.C. may be required.
Qualifications - Minimum of B.Sc.; postgraduate training in Botany preferred; demonstrated knowledge and considerable experience in angiosperm identification; demonstrated experience in field collecting.
Closing date June 17, 1998. For complete information please contact Ms. Terry L. Johnson, Phone: 250-387-2263, Fax: 250-953-4336. Competition no.: RB98:1218
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