BEN # 280
aceska at victoria.tc.ca
Tue Jan 22 04:05:31 EST 2002
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No. 280 January 22, 2001
aceska at victoria.tc.ca Victoria, B.C.
Dr. A. Ceska, P.O.Box 8546, Victoria, B.C. Canada V8W 3S2
A RADICAL VIEW OF BRYOPHYTE BIOLOGY:
MOSSES ARE FROM MARS, VASCULAR PLANTS ARE FROM VENUS
From: Brent Mishler [bmishler at socrates.berkeley.edu]
In what ways does bryophyte biology differ from that of vascular
plants (tracheophytes)? The short answer: in almost every way
possible! The groups didn't evolve on different planets, but
their differences could almost make you think they did. They
certainly adopted very different approaches to being a land
plant on this planet. Many aspects need much more study, but
what is known about bryophyte biology suggests that in general
the bryophytes differ in most ways in their biology, ecology,
and evolution from tracheophytes.
Major differences in bryophyte biology from tracheophytes in-
1. _Haploid dominance in the alternation of generations._
The green, vegetative part of the life-cycle in bryophytes
is haploid. Without the genetic benefits of dominance, genes
acting in the gametophyte are presumably subject to rela-
tively severe selection.
2. _Extensive phenotypic plasticity._
Studies have shown that bryophytes tend to have very high
amounts of morphological and physiological plasticity. This
may compensate for their demonstrated low levels of ecotypic
differentiation (perhaps due to haploidy).
3. _Poikilohydry and desiccation-tolerance._
Poikilohydry is the rapid equilibration of the plant's water
content to that of the surrounding environment, while desic-
cation tolerance is the ability of a plant to recover after
being air-dry at the cellular level. All bryophytes have
these abilities to some extent, but this was lost in the
larger, more complex, and endohydric tracheophytes.
4. _Need for free water for sexual reproduction._
A residual feature of the early land plants is the con-
straint imposed by the swimming sperm. Swimming gametes have
short dispersal distances which leads to frequent inbreeding
in monoicous species and lack of sporophyte production in
5. _The clump as a "super-organism"._
Many mosses and some liverworts are essentially social
organisms. This results from the combination of clonal
growth, poikilohydry, and external water conduction. The
plants in a clump are subject to natural selection as a
group. Intimate contact of each vegetative cell with the
environment, due to poikilohydry, lends itself to interplant
chemical communication via pheromones.
6. _Heavy reliance on asexual reproduction._
Due to the difficulty of achieving fertilization, many
bryophytes have evolutionarily lost functional sexuality.
Since bryophytes grow from an apical cell, somatic mutation
allows genetic variation even within clones.
7. _Small stature and the occupation of microhabitats._
Small size, lack of roots, and poikilohydry means that
bryophytes are in a close relationship with only their
immediate microenvironment. Over geological time, they may
be less influenced by climatic change, and linger in
8. _Less selection pressure from the biotic component of the
environment than from the physical component._
Vagility and establishment abilities of bryophytes are
relatively poor. Available substrates are not filled in most
mesic and xeric environments (although they may be in some
hydric environments). The presence of other bryophytes
nearby often appears beneficial to growth.
9. _Relatively slow evolutionary rates in morphology._
The fossil record of bryophytes indicates that ancient forms
are very similar to modern ones. Biogeographically,
bryophytes tend to follow the same historical patterns of
disjunction as tracheophytes, but at a lower taxonomic
level. This may indicate that developmental constraints play
an unusually important role.
The overall effect of these features on the evolutionary ecology
of bryophytes makes them profoundly different. By studying
bryophytes and comparing their life-style to that of
tracheophytes, we can learn to observe structure closely, think
critically about evolutionary inferences, and comprehend how
different lineages can take different functional paths in
response to the same stimuli.
[Abridged from Mishler, B.D. 2001. "Book review - The biology of
bryophytes: Bryophytes aren't just small tracheophytes."
_American Journal of Botany_ 88: 2129-2131. - A review of:
_Bryophyte Biology._ by A. Jonathan Shaw and Bernard Goffinet
(eds.). 2000. Cambridge University Press. x + 476 p. - For the
review of this book by Wilf Schofield see also BEN # 259.]
BOOK REVIEWS AND NOTICES
From: Adolf Ceska [aceska at victoria.tc.ca]
Jacobsen, Arthur Lee. 2001. _Wild plants of Greater Seattle: A
field guide to native and naturalized plants of the Seattle
area._ Arthur Lee Jacobson, Seattle. 494 p. ISBN 0-9622918-2-
x [softcover] Price: US$24.95
Available from: Arthur Lee Jacobson, 2215 E. Howe Street,
Seattle, WA 98112 e-mail: alj at consultant.com; web site:
Line drawings (most of them by J.R. Janish from Hitchcock et al.
_Vascular plants of the Pacific Northwest_) accompany descrip-
tions of about 500 vascular plants. The descriptions contain
information about the main diagnostic characters, intraspecific
variation, biology and ethnobotany of each species. Forty intro-
ductory pages list plants of various habitats, summarize their
edibility and give month-by-month accounts of their phenology.
An annotated checklist of about 1,270 species gives more details
on their distribution in the Greater Seattle area.
Kershaw, Linda, J. Gould, D. Johnson, & J. Lancaster [eds.].
2001. _Rare vascular plants of Alberta._ University of Al-
berta Press & The Canadian Forest Service, Edmonton, Alberta.
xliv+484 p. ISBN 0-88864-319-5 [softcover] Price: CDN$29.95
Raincoast Books, 9050 Shaughnessy Street
Vancouver, BC, CANADA V6P 6E5
Customer service: 1-800-511-6024 Fax: 1-800-565-3770
E-mail: custserv at raincoast.com or info at raincoast.com
This publication describes approximately 485 vascular plants
that are considered rare in Alberta. In a one-species-per-page
format, this manual gives the name of the species, most common
synonyms, description, habitat and notes on similar species.
Species are illustrated with colour photographs and/or line
drawings, and for most species, maps of their distribution in
North America and in Alberta are provided. The work is a result
of intensive floristic surveys that included 30 direct con-
tributors and about 100 amateur botanists.
Besides the species treatments, the book gives a good introduc-
tion to problems of rare plant studies, and a good description
of the phytogeography of Alberta. Several appendices provide
interesting reading (yet another key to Alberta _Botrychium_
species!), and an illustrated glossary and close to 300 litera-
ture citations conclude this handy publication.
When I first opened the book, I had the impression that it was
yet another book in the successful plant guide series published
by Lone Pine Publishing. Not so. However, although it was pub-
lished by the University of Alberta, editor Linda Kershaw,
formerly of Lone Pine, had an obvious and significant influence
on the format of this publication. The University of Alberta
Press, Canadian Forest Service, Alberta Native Plant Council
(Alberta's own version of a Native Plant Society), four editors,
30 contributors and about 100 volunteers should be commended for
this great book.
Phipps, James B. & Paul M. Catling. [Eds.] 2001. _Bioconserva-
tion and systematics: proceedings of the Canadian Botanical
Association Conference Symposium in London, Ontario, June
2000_. Canadian Botanical Association, Ottawa. iii+101 p.
ISBN 0-9689565-0-5 [softcover] Price: CDN$23.00 (US$17.00) in
Canada and USA, CDN$33.00 (US$21.00) overseas.
Send a check made out to "Canadian Botanical Association" to:
Dr. Mel Fisher
407 Main Street
Canada S0K 0A0
Prices include shipping and handling.
This is a collection of papers presented at the "Bioconservation
and Systematics" symposium organized by the Canadian Botanical
Association (CBA/ABC) at the annual general meeting in 2000. The
symposium addressed the theme common to other similar symposia,
such as one organized by the Missouri Botanical Garden (_Annals
of the Missouri Botanical Garden_, vol. 87, no. 1, 2000) or by
the Jepson Herbarium (_Madrono_, vol. 47, no. 2, 2000): What is
the role of biosystematics in the exploration and preservation
of plant biodiversity?
The symposium organized by the Canadian Botanical Association
included the following contributions:
Bioconservation and Systematics - Symposium Introduction (James
A never-ending role for biosystematics in the protection of
vascular plant biodiversity in Canada (Paul Catling),
Planning with plants in Illinois (Kenneth Robertson),
The role of Conservation Data Centres in the conservation of
Canada's flora (Michael Oldham & Peter Sorrill),
Floristics and conservation: an example from Newfoundland (Luc
Evaluating hybridization as a cause for species endangerment: a
role for systematics in plant conservation (Brian Husband &
Kevin Burgess), and
Can conservation help conserve rare plants in the twenty-first
century? (Anton Reznicek).
My posting on palindromes stimulated more "Letters to the
editor" than any other botanical posting in BEN. - AC
Costas A. Thanos [cthanos at biol.uoa.gr] wrote:
In regard to the palindromic phrase in BEN 279, a few comments:
1. The phrase was 'invented' by Byzantine Greeks (the 'middle'
ones, not ancient Greeks) - so it was an early Christian
2. The original inscription was made on a fountain outside
Saint Sophia, in Constantinople (today Istanbul, Turkey),
the capital of the Byzantine Empire. It was made during the
6th century AD, during the reign of Emperor Justinianus (who
commanded the construction of the magnificent cathedral).
3. The correct translation is: 'Wash sins not only face'.
The Greek word (although palindrome is perfectly Greek as well)
for the phrases that can be read both ways is 'cancer phrase' or
'cancer text'. Cancer is crab of course.
The spelling in Greek is
Î^ÝÎ^ÙÎ¨Î^ßÎ^Ý Î^ÑÎ^ÝÎ^ßÎ^ÜÎ^×Î^ÜÎ^ÑÎ¤Î^Ñ Î^ÜÎ^× Î^ÜÎ^ßÎ^ÝÎ^ÑÎ^Ý Î^ßÎ¨Î^ÙÎ^Ý
- I guess you will need to install Greek fonts to read it
properly. The transliteration you used in the BEN is the closest
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