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BEN # 176
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No. 176 November 11, 1997
aceska@freenet.victoria.bc.ca Victoria, B.C.
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Dr. A. Ceska, P.O.Box 8546, Victoria, B.C. Canada V8W 3S2
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THE WESTERN BLACK-FRUITED HAWTHORNS:
MORE COMPLEXITY THAN FORMERLY SUSPECTED
From: Rhoda Love <rglove@oregon.uoregon.edu>
When I first became interested in the western black-fruited
hawthorns in the 70s, their taxonomy and biogeography seemed
straightforward. Hitchcock et al. informed me that west of the
Cascades grew 20-stamen C. douglasii var. suksdorfii; while east
of the Cascades, and disjunctly in the Great Lakes region, was
found 10-stamen C. douglasii var. douglasii. I worked then in
the Willamette Valley of Oregon, where plants fit the Hitchcock
description of var. suksdorfii. Now and then I visited the
Wallowas where hawthorns fit the description of var. douglasii.
The taxonomy seemed simple and I felt lucky to be working where
the hawthorn story was straightforward, because I knew that in
the eastern US, the Crataegus situation was complicated by
hybridization, polyploidy, and apomixis. However, in the inter-
vening years, as a number of workers have begun to look more
closely at our western varieties, we find that the goblins which
make Crataegus study so complicated and challenging in the east,
are present to bedevil us here as well.
Historically, black-fruited hawthorns were collected in the
Columbia River drainage by Lewis and Clark in 1806, by David
Douglas and John Scouler in 1825, by Thomas Nuttall in 1834, and
extensively by W. N. Suksdorf in the early 1900s. Meriwether
Lewis' collection was misidentified by Frederick Pursh and did
not influence later taxonomy. David Douglas' collection became
the type for the species C. douglasii. Nuttall's collection,
like Lewis' was confused with another group. Finally, it was the
careful collecting of Suksdorf and his collaboration with C. S.
Sargent of the Arnold Arboretum that led, in 1907, to the recog-
nition of the 2 varieties noted above. Here the taxonomy stood
until present-day botanists began to study the group more
closely. Notably, ongoing work by J. B. Phipps, M. Muniyamma, T.
A. Dickinson et al., R. C. Evans, S. J. Brunsfeld and F. D.
Johnson is beginning to shed light on what is proving to be a
much more complicated situation than formerly believed.
In terms of biogeography, it is now clear that 20-stamen, black-
fruited entities are not found solely west of the Cascades, nor
are 10-stamen forms found solely on the east side. Brunsfeld and
Johnson of the University of Idaho have found a number of sites
where var. suksdorfii and var. douglasii are sympatric in east-
ern Oregon, eastern Washington and Idaho, and I have noted both
varieties in the San Juan Islands of Washington State. As for
ecology, workers have noted that var. suksdorfii populations are
usually associated with relatively mesic sites, while var.
douglasii seems able to inhabit not only mesic but also rela-
tively xeric habitats. Genetically, most 10-stamen (var. doug-
lasii) individuals tested have proved to be tetraploids;
however, while many 20-stamen (var. suksdorfii) individuals are
diploid, various degrees of polyploidy have been found in this
group by Dickinson and his colleagues. In terms of breeding
system morphology, while 10-stamen individuals tested have,
perhaps as expected, shown evidence of apomixis, some 20-stamen
individuals also reveal unreduced gametophytes.
In 1965, E. P. Kruschke, suggested that the differences between
var. suksdorfii and var. douglasii were important enough to
raise the former to species level. Brunsfeld and Johnson also
proposed raising var. suksdorfii to specific rank in 1990.
Dickinson and his co-workers, of which I am one, have felt that
the diploid var. suksdorfii may have given rise to the
tetraploid var. douglasii through a switch to apomixis with
concomitant loss of a whorl of stamens. This was an event which
we believed may have happened and continues to happen spon-
taneously at various places and at various times in response to
environmental stress. For this reason, we have come to agree
with Kruschke and Brunsfeld and Johnson, that Crataegus suksdor-
fii, as the putative diploid parent, deserves to be raised to
species rank. Consequently, in a paper in preparation, Dickinson
and I will designate a lectotype of Crataegus suksdorfii from
among sheets collected by W. N. Suksdorf in 1904-1905. I have
incorporated this view in my treatment of Crataegus for the
Oregon Checklist. (The Checklist is preliminary to the new
Oregon Flora being produced at Oregon State University under the
direction of Aaron Liston and Scott Sundberg.) The two black-
fruited hawthorns thus become Crataegus douglasii Lindl., and
Crataegus suksdorfii (Sarg.) Kruschke, species with 10 and 20
stamens, respectively.
This should be the end of the black-fruited hawthorn story, at
least for the present, but it is not. Steve Brunsfeld has
proposed a new and most intriguing hypothesis: that what we call
Crataegus douglasii may actually have arisen through hybridiza-
tion between Crataegus suksdorfii and what Hitchcock refers to
as Crataegus columbiana. (The latter was designated C. piperi by
J. Phipps in 1995. See his interesting paper on C. columbiana,
the "phantom taxon," in Taxon 44: 405-408.) The hybridization
hypothesis is presently being tested in Brunsfeld's lab and
Crataegus workers eagerly await the results. Looking at a mixed
population of both 20- and 10-stamen hawthorns in fruit near Mt.
Adams this July, and noting some intriguing variations in fruit
shape, size, and color, I could not help but think I might be
observing genetic mixing. Here I shall leave this brief discus-
sion of the western black-fruited hawthorns, having alerted BEN
readers to the possibility of more startling revelations to
come.
For further reading:
Brunsfeld, S. J. and F. D. Johnson. 1990. Cytological, mor-
phological, ecological and phenological support for specific
status of Crataegus suksdorfii (Sarg.) Kruschke. Madrono 37:
274-282.
Dickinson, T. A., S. Belaousssoff, R. M. Love, and M. Muniyamma.
1996. North American black-fruited hawthorns I: Breeding
system correlates, and their possible evolutionary sig-
nificance in Crataegus sect. Douglasii Loudon. Folia Geobot.
Phytotax. 31: 355-371.
Dickinson, T. A. and Rhoda M. Love. 1997. What IS Douglas haw-
thorn? IN: T. N. Kaye, et al. editors. Conservation and
Management of Native Plants and Fungi (a symposium). Native
Plant Society of Oregon, Corvallis, Oregon.
Evans, R. C. and T. A. Dickinson. 1996. North American black-
fruited hawthorns (Crataegus section Douglasii Loud.): II
Floral development of 10- and 20- stamen morphotypes in
Crataegus section Douglasii (Rosaceae: Maloideae). American
J. Botany 83: 961-978.
Love, R. and M. Feigen. 1978. Interspecific hybridization be-
tween native and naturalized Crataegus (Rosaceae) in western
Oregon. Madrono 25: 211-217.
VEGETATION OF NORTHERN EUROPE BY KLAUS DIERSSEN
Dierssen, Klaus (unter Mittarbeit von Barbara Dierssen). 1996.
Vegetation Nordeuropas. [Vegetation of Northern Europe.]
Verlag Eugen Ulmer, Stuttgart. 838 p. ISBN 3-8001-2700-8
(Ulmer) or ISBN 3-8252-8115-9 ("UTB - Grosse Reihe"). Price
DM 148.00
Ordering information: Verlag Eugen Ulmer, Postfach 700561,
70574 Stuttgart, Wollgrasweg 41, Germany. For e-mail try:
info@ulmer.de
This book is over 800 pages of pure enjoyment! It describes the
vegetation of an area "from Denmark to the Spitzbergen, and from
Iceland to Karelia (Finland)". The main core of the area is in
fact the Scandinavian Peninsula. (British Isles, Baltic states,
and northern parts of Russia are not included).
The introductory chapters describe the geology and biogeography
of the area, its postglacial history, and the history of land
use. The treatment of vegetation is divided into chapters on
forests, aquatic and riparian vegetation, vegetation of mires
and peatbogs, and vegetation that has been slightly and strongly
modified by human activities. The final chapter gives a detailed
classification scheme of plant communities of the area. Each
chapter deals with the floristic classification of the respec-
tive plant communities, and describes their ecology. The
ecophysiology of major plant groups is described in each chapter
in order to understand how the plant communities function.
The vegetation classification combines results of Scandinavian
schools of vegetation science and Cajander's school of forest
typology, and presents them in the framework of the Braun-
Blanquet hierarchical classification. Prof. Dierssen published
the overall classification of wetlands of NW Europe earlier in
his 1982 monumental work "Die wichtigsten Pflanzengesellschaften
der Moore NW-Europas," Jard. Bot. Geneve. This present class-
ification scheme covers all plant communities and provides an
excellent key to understanding the vegetation of Northern
Europe. A special section of the classification deals with
communities of bryophytes and lichens.
The book is richly illustrated with 96 colour photos, 488 black-
and-white photos and drawings, and 112 tables. The format is
reminiscent of Ellenberg's "Vegetation Mitteleuropas ..." (see
BEN # 169). One feature that surprised me most was the language.
The book is written in German; however, the German used in the
book is simple, clear, and straightforward, and one can under-
stand it even with a limited knowledge of the language.
Nevertheless, I hope that the English edition will follow soon.
NEW FLORA OF THE BRITISH ISLES - SECOND EDITION
Stace, Clive. 1997. New flora of the British Isles. Second
edition. Cambridge University Press, Cambridge. 1130 p. ISBN
0-521-58933-5 [plastic cover] Price: US$85.00
Ordering information:
Cambridge University Press
The Edinburgh Bldg., Cambridge CB2 2RU, United Kingdom
40 West 20th Street, New York, NY 10011-4211, USA
10 Stamford Road, Oakleigh, Melbourn 3166, Australia
The first edition of this Flora appeared in 1991 (see BEN # 53).
The author aimed for "exactly the same kind of Flora" he always
wanted to have for his own use. Such Flora should be user-
friendly, complete, selectively illustrated and not too expen-
sive. The first edition had tried to fulfill these criteria.
The new edition includes 200 new species and subspecies and with
the additional extra hybrids, the total number of treated taxa
covered is about 4,600. A new treatment of Rubus, Euphrasia,
Taraxacum and Hieracium has been provided. Another important
addition is the inclusion of chromosome numbers for all taxa
where known. The illustrations were expanded to include the
additional taxa, and the typographical execution of the book is
much better than in the first edition.
Both professional and amateur botanists can envy their col-
leagues in the British Isles for having this book. Its clear
keys and numerous detailed illustrations (often scanning
electron microphotographs of seeds, fruits, or floral parts)
make the identification of plants easy. The Flora includes both
native and alien species (well established introductions and the
'casuals'). Introduced species represent about 20 per cent of
the flora of British Columbia and most of those species are well
covered in this new edition. In addition we may have almost the
same percentage of circumpolar species that are again well
treated in the New Flora of the British Isles. This Flora is
thus an important reference for identification of many species
of the flora of the Pacific Northwest.
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