BEN # 176

Adolf Ceska aceska at CUE.BC.CA
Wed Nov 12 03:25:37 EST 1997


                                                   
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No. 176                              November 11, 1997

aceska at 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 at 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 at 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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Also archived at   http://www.ou.edu/cas/botany-micro/ben/
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