FROMTHE WORKSHOPS ON SELECTED PLANT GROUPS
|During the Panarctic Flora Year at the
Centre of Advanced Studies (1998-99), eight workshops combining experts from different
countries and taxonomic traditions were held in Oslo and St. Petersburg. The
plant groups discussed were (1) the Cerastium alpinum/arcticum complex, (2) Draba,
(3) Dryas, (4) the Scapiflora/Meconella group of Papaver, (5) the
grasses (Poaceae), (6) the Potentilla nivea group, (7) Salix, and (8)
The Cerastium workshop
The grass (Poaceae)
The Salix workshop
initial discussions concerning the genus Cerastium were undertaken during a meeting
in St. Petersburg in December 1998 by R. Elven and Dr. V. Petrovsky, and a
mini-workshop on the Cerastium alpinum-arcticum complex took
place in Oslo 9.-10. March 1999, involving Dr. S. Aiken (Ottawa), Dr. A.K. Brysting (Oslo)
and R. Elven (Oslo). The occasion was to discuss the new views as to division of the
complex in the North Atlantic area (especially by A. Brysting and A. Hagen, Oslo) and how
this perspective might influence the treatment of the complex in arctic Canada. We had a
large number of specimens available from The Canadian Museum of Nature (CAN) available.
The workshop was followed up by a revision of the specimens from the Canadian Arctic
Archipelago by Brysting & Elven, applying to these the criteria previously used for
the North Atlantic variation.
In the Arctic, four major species have been accepted: the nearly
circumpolar and morphologically unproblematic C. regelii s. l. (including C.
jenisejense), the broadly amphi-Beringian C. beeringianum, and the broadly
amphi-Atlantic C. alpinum and C. arcticum s. l. The studies in recent years
of the North Atlantic area confirm that the probably tetraploid C. alpinum and the
probably hexaploid C. arcticum s. l. are closely related and C. alpinum may
be responsible for a large part of the genes in C. arcticum s. l. (see Brysting
& Hagen in the this volume). Cerastium arcticum s. l. is, however,
morphologically and genetically heterogeneous, with a comparatively southern entity in
Fennoscandia, the British Isles, Iceland, and possibly Southwest Greenland, and a northern
entity in arctic European Russia, Svalbard, most of Greenland, and northeastern North
America. They should be recognized as two separate species: the name C. nigrescens
applied to the southern entity (typified from Shetland), and C. arcticum to the
northern taxon (typified from West Greenland). There still are some unsolved questions as
to the SW Greenland materials.
There are two competing circumpolar treatments of the taxa.
Hultén (1956) emphasized hybridization and introgression, whereas Böcher (1977) saw them
as an old, stabilized polyploid complex. Currently, our opinion is closest to
Bochers. Due to the differing treatments and assumed lack of diagnotic characters,
many recent authors treating the Greenlandic and American plants have lumped all into an
extremely widely defined C. alpinum. The questions concerning the Canadian
materials were, therefore:
- The applicability in America of the characters found useful in separating entities in
the European part of the North Atlantic area;
- The extent eastwards in America of C. beeringianum and the distinctness of this
entity as compared with the others;
- The presence and extent westwards of C. alpinum in America; (d) The entities of
the North Atlantic C. arcticum s. l. to which the American material might belong;
- The usefulness for the proposed subspecific divisions of C. arcticum (Hultén,
Böcher) and C. beeringianum (Hultén).
The results were comparatively clear on all these points. The
diagnostic characters applied in Europe were equally applicable to American material of C.
alpinum and C. arcticum s. l., and a set of characters was found to separate C.
beeringianum equally well. Cerastium beeringianum was found distributed
eastwards to the Hudson Bay area, Ellesmere Island, and probably also NW Greenland, but it
was mainly replaced by C. arcticum in the east. Cerastium alpinum was
identified clearly in the materials from the easternmost parts of Canada, especially from
Baffin Island, but a comparison with the European subspecific entities remains to be done.
The American C. arcticum is of the northern type, corresponding to C. arcticum
s. str., conforming very well with the Greenland and Svalbard material. Cerastium
arcticum reaches west to the central parts of the Arctic Archipelago, where it becomes
completely replaced by C. beeringianum. Although we found a great deal of variation
in C. arcticum, there was little support for a further split of C. arcticum
(or any of the other species) into clearly definable geographical races.
The Draba workshop
By Reidar Elven, Vladislav V. Petrovsky & Christian Brochmann
workshop (15.-19. March 1999 in Oslo) was mainly based on the draft checklist of Dr. V.V.
Petrovsky (St. Petersburg). It was attended by B. Andersen (Oslo), Dr. C. Brochmann
(Oslo), R. Elven (Oslo), H.H. Grundt (Oslo), Dr. V.V. Petrovsky (St. Petersburg) and A.-C.
Scheen (Oslo). Some pre-workshop work was done by Grundt, Petrovsky and Elven in the St.
Petersburg herbarium in November and December 1998. In addition to the draft checklist,
abundant herbarium material from the North Atlantic area and a fairly large representation
from Siberia, the Russian Far East, and from Alaska was available. Live plants from Alaska
were also studied in the Phytotrone, Biological Institute, University of Oslo. All major
arctic groups and most species were represented in the material studied.
The genus Draba is one of the larger in the Arctic, with between
50 and 60 accepted species (and some subspecies). The subgeneric structure applied today
to the Arctic taxa is mainly that of Tolmachev (1939, 1975) from the
Flora USSR and Arctic Flora of USSR, in which the arctic species are distributed among
about 14 series. As this system applies only to the Russian species, some additions are
needed to encompass a few Cordilleran species that do not cross the Bering Strait. Some of
the series are obviously so closely related that it is difficult to find biologically
meaningful distinguishing criteria, especially between Lacteae and Pilosae
and between Cinereae and Hirtae (and partly also Rupestres).
When these series are merged, the majority of the arctic species falls
into six groups: Alpinae with 8 or more species, Cinereae/Hirtae/Rupestres
with somewhere between 10 and 15 species, Incanae with 2 to 3 species, Lacteae/Pilosae
with ca. 10 species, 'Micropetalae' (Tolmachev's Oblongatae must change its
name) with 2 to 3 species, and Nivales with 4 species. In these, except for Incanae,
there seem to have been speciation in or close to the Arctic as at least one species in
each group is nearly or entirely restricted to the Arctic. The remaining series are
represented in the Arctic by 1 to 2 species each, obviously of temperate-alpine or
Several species are known only from very restricted areas and from few
collections, and there is probably an over-description of such local species. Examples are
D. allenii from northeasternmost America, D. boecheri from Greenland (one
site), and D. sambukii from Taimyr. A very careful study of the specimens, and in
some cases also investigation of genetic markers, are needed before such species can be
confirmed or rejected.
A second problem is the effect of taxonomic traditions; taxa are often
not treated in the same way across national boundaries. Obvious cases are found in: (1)
Micropetalae where Russian, Norwegian and some Danish (Greenland)
authors recognize 2 to 3 species at different ploidy levels, whereas American authors
recognize only one in their equally heterogenous material; (2) Alpinae where the
name D. alpina often is applied in a wide sense for entities from diploid to
14-ploid levels in America and Russia but in a narrow sense for a decaploid in the North
Atlantic area; and (3) Cinereae, where Russian, Norwegian, and Danish (Greenland)
authors distinguish more or less clearly between the decaploid D. arctica and the
hexaploid D. cinerea whereas North American authors unite them. Several additional
examples might have been cited.
There is, however, no essential difference in how scientists in the
different botanical traditions recognize and circumscribe species in Draba. We
agree in most aspects, but the intensity of investigation in various groups
has differed in different areas. The main task now lies in comparing materials to reach
cross-boundary consensus. The usefulness of such an approach was demonstrated during the
workshop(s) recognizing two new entities for Europe - D. oblongata R. Br. for
Svalbard and D. parvisiliquosa Tolm. for North Fennoscandia - two for Alaska - D.
kamtschatica (Ledeb.) N. Busch and D. pilosa DC. - and finding an unnamed
parallel to the North Atlantic D. oxycarpa Sommerf. in the Beringian area.
The Dryas workshop
By Inger Nordal, Boris A. Yurtsev & Marianne Phillip
workshop (15.-18. March 1999 in Oslo) was attended by Dr. B.A. Yurtsev, Dr. M. Phillip and
Dr. I. Nordal. Discussions were based on a draft checklist by Yurtsev, the key by Yurtsev
for Arctic Flora of USSR (1984) and his survey of the genus (Yurtsev 1997), the genetic
and morphologic studies of Dryas from Greenland and Svalbard by Phillip and
collaborators (see Siegismund & Phillip in this volume), and on herbarium specimens,
mainly from the North Atlantic areas, but also some American and Beringian ones. The
Russian key was translated into English, and a slightly simplified translation (excluding
some hybrids included in the original key) is presented at the end of this summary to
facilitate further work with the genus.
Yurtsev (1997) recognizes 15 species globally, of these nine reach the
Arctic: D. grandis Juz. and D. drummondii Richardson (in sect. Nothodryas)
and D. ajanensis Juz., D. chamissonis Spreng. ex Jurtz., D. crenulata
Juz., D. incisa Juz., D. integrifolia Vahl, D. octopetala L., and D.
punctata Juz. (all in Sect. Dryas). Two of these - D. ajanensis and D.
punctata - are represented by two subspecies each in the Arctic, and D. octopetala
is represented by its subsp. subincisa Jurtz. The genus has its center of diversity
in northeastern Asia and (partly) northwestern North America, whereas few entities are
found in the North Atlantic areas, i.e. northeastern North America, Greenland and northern
The taxa recognized by Yurtsev are mainly defined and delimited by
characters from indumentum, glands (presence/absence and types), and leaf shape, incision
and structure. In Siberia, all the presumed primitive features are present in some
lineages of Sect. Dryas, that is, all the types of hairs and most types of glands.
These are also present together with the assumed primitive tendency of compound leaves in
Sect. Nothodryas, purportedly a sister group of Sect. Dryas. The only
novelty later evolved in Sect. Dryas, according to Yurtsev, is the sessile, convex
lens-shaped glands characteristic of D. punctata (including subsp. alaskensis)
and in taxa outside the Arctic in subsp. hookeriana from The Rocky Mountains and
the related D. viscosa.
In general, the assumptions of a northeastern Asian center, of a
subsequent spread from there into the Arctic and other areas, and of morphologic overlap
and hybridization, are not disputed. The discussions concerned the interpretation of the
morphological variation and its taxonomic significance, especially the use of single
characters and of assumption of hybridogenous origins of taxa with intermediate features.
As a test case, the variation in the North Atlantic areas was
discussed. Nordal and Phillip recognize two species - D. integrifolia in
northeasternmost America and Greenland and D. octopetala (s. l.) in northern
Scandinavia, Iceland, Svalbard and East Greenland - and intermediates between them in
parts of Greenland. In the same area, Yurtsev recognize four species - D. chamissonis
(Notheast America, Greenland), D. integrifolia (NE America, Greenland), D.
octopetala subsp. subincisa (East Greenland, Svalbard, northernmost mainland
Europe), and D. punctata subsp. punctata (East Greenland, North Europe).
These discrepancies have to be resolved before a consensus checklist is attained. No such
consensus was reached during the workshop.
Yurtsev recognizes three taxa in Svalbard and in East Greenland: D.
octopetala subsp. subincisa, D. punctata subsp. punctata and
their hybrid, D. x vagans. The paramount diagnostic character of D. punctata,
the lens-shaped glands, was found by Siegismund & Phillip (this volume) to be more or
less randomly distributed among and within populations in Svalbard, and the presence of
glands was found not to be correlated with leaf morphology or isoenzyme pattern. In a
North Atlantic perspective, thus, the gland character appears to Nordic botanists as an
intraspecific polymorphism. Greenland variation is a similar case.
According to Yurtsev, the observed patterns in Svalbard and Greenland
represent marginal introgression zones for more or less interfertile taxa originating in
other areas, D. punctata in Siberia, D. integrifolia in America, and D.
octopetala s. str. probably in North Europe. The question is how to handle the
situation taxonomically. If the arctic plants of Sect. Dryas constitute only a
partially structured panarctic gene-pool created by extensive hybridization, this might be
handled in two ways: (1) By attempting to identify both the original species and the
hybrid combinations and to characterize and name them accordingly (Yurtsev's proposal);
and (2) By including assumedly interfertile and geographically overlapping entities within
more widely defined species (Nordal's and Phillip's proposal).
There is an obvious need for modern analysis of both arctic and
non-arctic Dryas, involving both more extensive morphological analysis,
investigation of molecular markers, and further application of ecogeographic methods. The Dryas
logo of the PAF project was partly chosen because this well-known and important arctic
genus still remains a taxonomic riddle.
Key to the genus Dryas in the Russian Arctic [hybrids removed]
From Yurtsev (1984, Arctic Flora of USSR 9 (1): 256-260), with
emendations and with hybrids removed.
oblong-oblanceolate, widest part above the middle, large with cuneate base and 1-4
separate teeth on upper petiole, blade flat, thick, subcoriaceous, with 6-13 equally
short oblique triangular directed upwards teeth on each side, upper surface dark green
glossy, with submerged veins, glabrous, the midvein simple hairs, sometimes (along with
petiole and stipules) with sparse minute, colourless subsessile, non-viscid glands and
without sessile amber, lens-shaped, viscid glands; not rarely leaf lower surface with
snow-white tomentum, midvein glabrescent, except for apex, petiole firm, thick,
glabrescent, much shorter than the blade with dark brownish, thinly branched hairs
sometimes with stipitate glands. Flowers during anthesis campanulate, suberect to
slightly nodding with ovate-lanceolate sepals, sepals and hypanthium densely covered
with long dark purple glands, petals narrow obovate, white. Styles in fruit 3-5 (-6) cm
long, densely covered with long hairs, strongly spirally twisted, violet, shining (nitide)
when immature D. grandis
Leaves of not as above, widest at the middle or
below, with cordate, sagitate, rotundate (rounded) or truncate, rarely
truncate-cuneate, base without teeth on the petiole, petioles not rarely nearly as
long as the blade. Flowers during anthesis erect and open. Styles in fruit usually
less than 3 cm long, weakly twisted, weakly glossy, rose to greenish when immature (sect. Dryas) 2
2. Leaves with entire margin or with
few teeth at the base of some leaves or at least with uppermost part of blade without
teeth, if blades crenulate along full length, then most teeth are very minute, shorter
than they are wide, rotundate and involute; blade coriaceous, thick with slightly
submerged veins (in D. crenulata); leaves lack branched hairs and stipitate
glands (appearance of glands or branched hairs on some leaves is the result of
hybridization with species of other sections) (subsect. Tenella) 3
Leaves more or less dentate along full length,
usually with blade rugulose, owing to deeply submerged veins 5
3. All leaves with entire margin,
rarely with teeth in lower part or at the base of blade, with wide sagitate base, upper
surface not rugose, glabrous or glabrescent except for median vein, or dense pubsecent
(var. canescens), lower surface white, tomentose or rarely glabrate D.
Leaf blade (at least in many leaves) dentate or
crenulate to apex or nearly so 4
4. Leaves narrow
lanceolate-oblongate or almost linear, strongly involute, margins not rarely
touching, coriaceous, thick, the upper surface glossy, not dark or bright
green glabrous or glabrescent without strongly submerged lateral veins, gradually
tapering towards the base, base rotundate (rounded), truncate, seldom subcordate, crenulate
almost along full length, lower part rarely with oblique acute teeth, lower surface
white-tomentose, with glabrous petioles and ciliate stipules. Scape slender, long,
somewhat twisted, not rarely with a subulate bracteole D. crenulata
Leaves normally wider, often ovate with
broad sagitate, cordate, rarely truncate base, thinner, at least some or almost
all dentate to apex or nearly so, teeth in lower half not rarely large, oblique
triangular, the upper surface glabrous or glabrescent, except for midvein, or densely
pubsescent (in var. incana), the lower surface white-tomentose. Scape thick or
slender, not twisted, without bracteole D. chamissonis
5. Leaves lacking dotted sessile
viscid or minute colorless, clavate glands on upper surface, lower
surface lacking branched and glanduliferous, hairs on midvein and petiole, with
slightly involute margins, dentate along full length with elongate, oblique
triangular teeth, the sinus between teeth, in lower half of leaf, sometimes reaches
midvein, not rarely gradually tapering to the base, usually coriaceous, glossy rugulose,
in living state often pale green, upper surface except for veins glabrous or with tomentum
(var. cana), lower surface with snowy-white tomentum or vein and petiole sometimes
softly spreadingly white pilose. Sepals narrowly lanceolate or linear lanceolate, densely
covered with dark purple glanduliferous hairs, without a mixture of branched hairs .D. incisa s.str. (subsect. Incisa)
Leaves with branched hairs and/or sessile and
stipitate viscid or minute colourless glands on midvein of lower surface and on
petiole, upper surface without glands or with dotted glands or minute colourless
subsessile glands 6
6. Leaves covered with sessile,
convex lens shaped, amber yellow, yellow green or reddish, dotted viscid glands
on upper surface, resin on older leaves due to hardened white secretions, lower surface
with sessile or stipitate yellow, reddish brown or almost purple, viscid
glands on veins and petioles, often with a mixture of brown branched and sometimes simple
white hairs; blade elongate elliptical to elongate-oblong or elliptical, widest at middle
with wide, obtuse or sometimes acute, long or short teeth, lateral veins on lower surface
not concealed by tomentum. Stipules with viscid glands (D. punctata, subsect. Punctatae)
Leaves lacking dotted viscid glands on upper
surface, also lack sessile and stipitate large viscid glands on veins and petioles of
lower surface; midvein of lower surface and petiole with branched, brown hairs, with a
mixture of simple white hairs; upper surface, veins on lower surface, and petiole and
stipules some times with minute, colourless subsessile glands not producing secrections
that harden to form white spots. Sepals, hypanthium, and upper part of scape often with
mixture of long purple glanduliferous and brown branched hairs (subsect. Dryas) 8
7. Leaves, covered on lower surface of
median and lateral veins with a mixture of brown branched hairs and viscid sessile
and stipitate, yellowish, brown or purple glands; upper surface with glabrous or
glabrescent submerged veins, with abundant viscid, dotted glands, more rarely with dense
white pubescence concealing sparse dotted glands (var. cinerea Jurtz.; with veins on lower
surface which are some time covered with a white tomentum, in addition to abundant
branched hairs, and inconspicuous glands) D. punctata subsp. punctata
Median and lateral veins of lower leaf surface
and petioles lacking branched brown hairs, but densely covered with purple
brownish or yellowish stipitate glands, often with an abundant mixture of sessile,
viscid verruciform glands D.
punctata subsp. alaskensis
8. Leaves usually ovate-oblongate
with cordate or nearly saggitate base, the widest part below the middle,
sub-coriaceous, with involut margins, often glossy with submerged veins, rugulose,
margins obliquely acute dentate, sinus between lower teeth can almost reach the midvein,
upper surface glabrescent, pubescent mostly only on veins, or with densely adpressed
pubescence (var. argentea), white tomentose on lower surface, between and on the
lateral veins, sometimes a part of leaves lacking branched hairs. Sepals usually acute-lanceolate
to linear-lanceolate, glabrous on the upper surface. Scapes with sparse dark stipulate
glands and/or branched hairs in upper part. Petioles not rarely without branched hairs D.
octopetala subsp. subincisa
Leaves elliptic, more rarely short- or
elongate-elliptical, or ovate-elliptical to oblongate-oblanceolate, the widest part
near or somewhat above the middle, with cordate, rotundate (rounded) or truncate base,
with short teeth, upper surface dull dark green, leaf thin, upper surface with
densely appressed pubescence sometime only between the veins, more rarely glabrescent,
pubescent on the deeply submerged veins, lower surface often with glabrate median and
lateral veins along with petiole densely covered with more or less short branched hairs,
usually also with numerous minute colourless, subsessile, non-viscid glands abundant on upper surface of leaf, petiole, and
especially stipules. Sepals ovate-lanceolate to oblongate-ovate, acute or obtuse,
some times pubescent on the upper surface (D. ajanensis) 9
9. Leaf upper surface canescent from
appressed hairs, sometimes with glabrate veins or green and glabrous between submerged
veins (var. viridis), leaves short-elliptical to elliptical with somewhat remote,
often obtuse, or double unequal teeth (can be similar in general appearance to leaves of D.
punctata, but shorter and less incised); lateral veins at divering up to right
angles from the midvein, as a rule not concealed by tomentum; minute colourless,
subsessile, non viscid, glands often very abundant, especially on petiole and stipules. A
plant of eastern part of Chukotka Peninsula, Alaska, and Yukon D. ajanensis
Leaf upper surface always canescent from
dense adpressed hairs not rarely with glabrate veins, oblong-oblanceolate or
oblong-obovate with short oblique acute, equal teeth; lateral veins almost
parallel, directed oblique upwards, forming a smaller angle with the midvein;
minute colourless glands on petiole and stipules inconspicuous (the plants of northern
coast of Sea of Okhotsk) D.
ajanensis subsp. ochotensis
The Papaver workshop
By Inger Nordal, David F. Murray, Orjan Nilsson, Vladislav V.
Petrovsky & Reidar Elven
workshop (October 1998 in Oslo) followed immediately on the Symposium, with many of the
same participants: Dr. D.F. Murray (Fairbanks), Dr. V. Petrovsky (St. Petersburg), Dr. Ö.
Nilsson (Uppsala), and Dr. I. Nordal, H. Solstad and R. Elven (Oslo). The workshop based
its discussions and other work on the discrepancies in treatments of the Scapiflora
Section of Papaver by Petrovsky and Solstad et al. (in this volume), Nilsson in
Jonsell (in press, Flora Nordica Vol. 2), and Kiger & Murray (1997, in Flora of North
America Vol. 3). Materials were available from the North Atlantic area and some from
arctic Canada, Alaska and Siberia. The workshop, in an extended sense, was continued in
some analysis of genetic markers and a morphometric attempt in autumn 1998 and study of
type specimens and other materials in the Komarov Botanical Institute in February 1999.
Two problematic themes were discussed during the workshop and
subsequent works: The lack of common species characterization and naming across the North
Atlantic (see Solstad et al. in this volume), and the level of species variation in the
Beringian area (see Petrovsky in this volume).
Superficial studies of herbarium specimens alone did not clarify the
application of names in the North Atlantic where the names P. radicatum, P.
lapponicum, P. dahlianum and P. polare are used with partly different
meanings in different areas. We made a morphometric program for registering variation in
most available characters and measured a selection of specimens from most major species,
including several Beringian ones. A numerical analysis failed to find clear limits, and
also failed to classify together specimens belonging to the same of to closely related
species. The reasons for this are probably that the large number of plastic characters
included obscured the pattern formed by presumed taxonomically important characters, and
that the total variation among the species is too large for a 'collective' analysis. The
analysis should rather focus on smaller groups of clearly related species within the
Some investigations of molecular markers (isoenzymes) were undertaken
on a selection of North Atlantic and Beringian taxa currently in culture in Oslo. Some
very initial results are: (1) that also morphologically very different Beringian species (P.
macounii in two subspecies, P. walpolei) showed much general molecular
similarity with the North Atlantic plants; (2) that the multilocus isoenzyme phenotype of
mainland Norwegian P. dahlianum (from where it is described and typified) was
identical with one of the phenotypes found in Svalbard (from where P. polare is
typified), more or less proving identity between P. dahlianum and P. polare
at species level; and (3) that one of the markers differentiating P. dahlianum/polare
from P. radicatum/lapponicum was present in one of the Beringian species (P.
walpolei). Investigations of molecular markers are obviously a powerful tool in
solving the problems in this complicated group. A fairly large material of live plants and
seeds was collected in the summer of 1999 through Greenland and arctic America, as a start
of this work.
The investigation of types and other specimens in St. Petersburg
convinced two of us (Elven, Solstad) that at least the majority of species described from
the NE Russian areas represent real taxa, and that the problems in the arctic parts of the
genus cannot be solved without a thorough and modern investigation of these.
The grass (Poaceae) workshop
By Reidar Elven, Nicolai N. Tzvelev & Susan G. Aiken
workshop on grasses (Poaceae) took place in St. Petersburg (22.-26. February 1999), with
attendance of Dr. S. Aiken (Ottawa), R. Elven (Oslo), Dr. N.N. Tzvelev (St. Petersburg),
and with translation and active participation by Dr. B. Yurtsev (St. Petersburg). The
discussions were mainly based on a draft checklist by Tzvelev and the abundant specimens,
including many types, present in the herbarium of the Komarov Botanical Institute, but
also with reference to the Poaceae part of the Flora of Canadian Arctic Archipelago and a
North Atlantic checklist.
Poaceae is the largest family of vascular plants in the Arctic.
Tzvelev's draft includes 282 species and subspecies, that is 10-15% or the estimated
arctic vascular flora. Most of the problems found throughout the arctic flora are
represented here, e.g. how to treat morphologically similar entities at different ploidy
levels, agamospermy, entities reproducing mainly or entirely vegetatively, polyploid
complexes with possible polyphyletic and hybridogenous origins, and different treatments
of similar (or identical) taxa across national boundaries.
The discussions revealed several discrepancies between the treatments,
discrepancies that will need much more discussion before a consensus can be reached. Some
of the major points were:
(1) Species are conceptualized more narrowly in the Russian draft than
commonly done now in North American and North European treatments. The draft accepts some
species in cases where westerners now accept only subspecies as, e.g., in the Poa
arctica and P. pratensis complexes and in Arctagrostis arundinacea/latifolia,
and accepts species also where the criteria used only defines varieties or ecotypes in
western opinion or pure synonymy as, e.g., in Hierochloe orthantha,
several Poas, and in one species of Arctagrostis. Even if both species and
subspecies are applied in all treatments, they are applied at slightly different levels.
(2) The importance of hybridization and agamospermy/-vivipary is viewed
differently. In Tzvelev's opinion, the very numerous cases of polyploid series in grasses
represent past hybridization events, in some cases also across current generic boundaries
and often across sectorial boundaries. This view influences the acceptance and
interpretation of both species and genera. It is, however, not uniformly accepted and
should not, in the opinion of Aiken and Elven, be used as taxonomic criteria without
proof. The opposite is the case with agamospermy and vivipary. This is often interpreted
as results of past hybridization in western tradition, and a sharp limit, as
species, is often drawn between presumed diploid sexual parents and their polyploid agamic
offspring, e.g. in Calamagrostis and Hierochloe. The same is the case with
separating between diploids and presumed or documented allopolyploid derivatives, e.g., in
Anthoxanthum. Russian tradition places more emphasis on morphological differences
than on assumed evolutionary pathways.
(3) The general acceptance of subspecies for zonal variation and cases
of intermediacy. In the draft, there are numerous cases of 2 to 3 vicariant subspecies or
species along the south-north gradient in cases where western traditions only
accept one species - e.g. in Alopecurus borealis and Calamagrostis lapponica
and C. stricta - the two or three entities often being separated by quantitative
characters only. The western interpretation is that these may be examples of
clinal variation, which is normal in most widely distributed species. The taxonomic
decision to accept separate taxa must depend on the presence of discontinuities in the
variation, similarly the decision to reject is based on an absence of breaks in the
We also looked at some specific cases and in the Festuca
brachyphylla complex we reached a unified opinion on how to define the species in a
circumpolar context and were then able to revise important parts of the Russian materials
available. In the intricate Deschampsia cespitosa complex, we agreed that both
western and eastern traditional treatments were unsatisfactory. A
future treatment must be a Panarctic effort based on a large-scale biosystematic study.
The Potentilla workshop
By Bente Eriksen, Inger Nordal, Jorun Nylehn & Boris A. Yurtsev
workshop (November 1998 and a few days in March 1999 in Oslo) was attended by B.
Eriksen (Gothenburg), J. Nyléhn (Oslo), B. Yurtsev (St. Petersburg), and partly also by
I. Nordal (Oslo). In the focus of the discussion were the variation and classification of
hair types found in different species aggregates within Potentilla sect. Niveae.
A scanning electron microscope study of hair types and hair ultra structure was initiated,
which during the year resulted in a joint paper on terminology and systematic distribution
presented in this paper (Eriksen & Yurtsev 1999). It is clear from this study that P.
sect. Niveae consists of three main species aggregates (see below), confirming the
preliminary results obtained of Eriksen (1997). It was also seen that a mixture of
parental hair types is not always expressed in the putative hybrids of the section. It was
concluded that the hair types are not inherited in a co-dominant way, the hybrids in
question are hybrids of other parents, or the plants in question are not hybrids at all.
The different hair types found in the above-mentioned study are
included in a list of characters and character states to be used for a morphometric study
of Potentilla sect. Niveae. This list, including also diagnostic characters
of leaves, flowers and fruits, might be found on the homepage of the "Potentilla
The list, a joint venture from the Potentilla workshop, is
presented in the hope that more botanists will eventually become interested and join the
project. Above all we need help to collect data in various herbaria. Inclusion of type
specimens in the study is of particular importance since misidentification is a large
problem within the group.
A draft check-list on the genus Potentilla for the Panarctic
Flora has been compiled by Yurtsev. It includes 70 taxa, of which 33 are proposed to be of
hybrid origin. In its present form this list reflects the taxonomy presented by Yurtsev (1984) in the Arctic Flora of USSR, and this will represent the
starting point for further work and discussions. It was agreed that the hypotheses on
hybrid taxa must be examined more thoroughly, and preferably also with molecular methods.
Under the section Niveae, three species aggregates identified in
the study on hair characters have been incorporated in the draft check list: The Potentilla
nivea aggregate with floccose tomentum and smooth straight hairs (including taxa like P.
nivea and P. crebidens in the Arctic); the P. arenosa aggregate (= the P.
hookeriana aggregate of Eriksen and Yurtsev 1999) with floccose
tomentum and verrucose, straight hairs (including taxa like P. arenosa, P. tomentulosa,
and P. chamissonis in the Arctic); and the P. uniflora aggregate with
crispate tomentum and smooth straight hairs (including taxa like P. uniflora and
P. villosa in the Arctic).
Phenotypic plasticity may cause large variation in leaf morphology (Eriksen & Nyléhn 1999). A shift in leaflet number and position from
trifoliate to digitate or digitate to pinnate induced by favorable growth conditions
indicates that supernumerary leaflets may be the result of mechanisms other than
Further, during the workshop, the genus Potentilla has been
formatted for the Delta database by Kjell-Tore Hansen in collaboration with Susan Aiken,
using Svalbard material as input.
B. 1997. Morphometric analysis of Alaskan members of the genus Potentilla sect. Niveae
(Rosaceae) Nord. J. Bot. 17: 621630.
Eriksen, B. & Nyléhn,
J. (1999). Cases of Phenotypic plasticity in leaves of Potentilla L. (Rosaceae).
Det Norske Videnskaps-Akademi. I. Mat. Naturv. Klasse, Skrifter, Ny serie 32:
Eriksen, B. & Yurtsev,
B.A. 1999. Hair types in Potentilla sect. Niveae (Rosaceae) and related taxa
terminology and systematic distribution. - Det Norske Videnskaps - Akademi. I. Mat.
Naturv. Klasse, Skrifter, Ny serie 32: 201-221.
Yurtsev, B. A. 1984. Genus
Potentilla L. [Rod Potentilla L.]. In: Jurtsev, B. A. (Ed) Arctic Flora of USSR 9 (1):
137234 (in Russian).
The Salix workshop
By Reidar Elven & George Argus
workshop (19.-27. April 1999 in Oslo) was based on drafts of a Panarctic checklist from
Dr. A. Skvortsov (Moscow) and Dr. G. Argus (Ottawa), In addition, treatments for
Alaska/Yukon (Argus 1973), the Russian Arctic (Skvortsov in Tolmachev 1966) and for the
whole of Russia (Skvortsov 1968), the Nordic area (R. Elven et al. in Jonsell in press), a
list for the North Atlantic areas (Elven unpubl.), and the infrageneric classification in
North America (Argus 1997) were reviewed. The workshop was attended by G. Argus (Ottawa)
and R. Elven (Oslo), but the comments of A. Skvortsov were solicited and have been
included. A fairly large selection of specimens from Siberia and the Russian Far East,
some specimens from Alaska and Canada, and an abundant material from the North Atlantic
areas, including NW Russia and Greenland, were at hand. Subsequent work has resulted in a
revised draft, which is presented in this volume.
Salix is one of the larger genera in the Arctic, with 50-60
species and subspecies. There were surprisingly few and small discrepancies among the
American, Russian and Nordic treatments. Skvortsov tended to accept broader species than
usually practiced by northwestern European and American authors in some groups, e.g., the S.
glauca, S. lanata and S. myrsinifolia groups, whereas Argus and Elven
had a broader species view than Skvortsov in, e.g., the S. arctica and S.
rotundifolia complexes. The draft proposal presented in the Salix checklist (in
this volume) is a consensus proposal rather than a compromise, even if points of
The species of Salix extending to the Arctic are derived from
numerous branches of the genus and belong to three subgenera and numerous
sections. The temperate-boreal character of Salix is also reflected in the large
number of species touching or only slightly extending across our arctic boundary. There
are probably no exclusively arctic species, and even species like S. arctica, S.
nummularia, S. polaris and S. rotundifolia have extensive alpine
extensions, especially in East Asia and western North America.
Salix is known for frequent polyploid taxa, probably of
alloploid origin and often results of intersectional crosses, as alloploid origins in Salix
often involve more distantly related diploids rather than close relatives. A subgeneric
classification would be better based on diploids rather than on the entire assemblage but
this is impossible as some series only include high polyploids.
Hybridization has been deemed of great importance in Salix,
especially in the Nordic tradition following Enander and Floderus, whereas it has been
given little attention in other traditions or assumed to be taxonomically unimportant. It
has been proved experimentally, several times, that very many species of Salix can
hybridize. That they also do so in nature is evident from variation patterns. The question
is whether this hybridization influences the species to any significant extent, and should
be recognized taxonomically. Our opinion is that hybridization (in the modern sense, not
of Floderus) seems to have little lasting influence on the species, especially at diploid
level, and can be disregarded in the PAF checklist.
The Saxifraga workshop
By Pavel Yu. Zhmylev, Christian Brochmann, Reidar Elven, Inger Nordal
& Vladimir Yu. Razzhivin
workshop was held in Oslo in the spring of 1999 and fully or partly attended by Dr. P.
Zhmylev (Moscow), Dr. V. Razzhivin (St. Petersburg), and Drs C. Brochmann, R. Elven, and
I. Nordal (all Oslo). Translation was carried out Katya Razzhivina and V. Razzhivin. The
discussions were particularly based on a new draft checklist of arctic Saxifraga by
Zhmylev, which in turn was based on his recent systematic reviews of the entire genus in
Russia and adjacent territories (Zhmylev 1997a, b), on a translation of parts of the Saxifraga
treatment in Arctic Flora of USSR (to Norwegian by Jan Wesenberg), and on the fairly
recent, comprehensive treatment of the genus by Webb & Gornall (1989), which focuses
on European species and represented the western tradition in the discussions.
Abundant herbarium material was available from the North Atlantic region, but only very
limited material was available from Alaska and Russia (in particular western areas).
Living material from the N Atlantic region was flowering in the phytotrone in Oslo at the
time of the workshop, and this material was important for clarification at some points.
This large, and probably polyphyletic (cf. several recent works by the
Soltis group), genus contains some 480 species traditionally classified into several
subgenera, many sections, and subsections. A main distinction between Zhmylevs
(1997) and earlier taxonomic treatments is that the new treatment splits the sections into
more subsections (the subsection level will probably be excluded from the Panarctic
checklist). The arctic species of Saxifraga represent many of the infrageneric
taxa, reflecting independent colonization of arctic areas by a number of different
evolutionary lineages in the genus. Most of the diversity is found in Siberia and North
America, and the lack of material from these areas (as well as the comparatively
superficial treatment of Russian and N American species in Webb & Gornall) limited our
discussions on the workshop. The North Atlantic area per se presents relatively few
taxonomic problems, but the North Atlantic variation represents, in some cases, only part
of a more complex circumpolar variation.
During the workshop we tentatively accepted arctic species and
subspecies belonging to four subgenera (Micranthes, Diptera, Hirculus, and
Saxifraga) and 13 sections. The workshop was, in the main part, characterized by consensus.
Examples of some problems as to width of species concepts and points that were clarified
1) Zhmylevs divides the arctic Russian material of subsection Rotundifoliatae
(sect. Chionophila, subgen. Micranthes) into a several species, which in the
American tradition have been recognized as subspecies of S. nelsoniana. A possible
compromise is to accept two species.
2) The extreme polymorphism within Saxifraga cespitosa (as well
as its distinction towards S. rosacea, in particular in S Greenland and the
British Isles) is poorly understood. New and partly unpublished data from Svalbard
indicate, for example, that S. cespitosa in this area comprises two genetically
fairly divergent lineages, one with large, white or rarely yellowish petals growing
primarily in gravelly pioneer sites, and one with smaller, deep yellow petals growing in
dense moss vegetation (cf. also Ronnings last edition of the Svalbard flora).
3) We examined living and pressed material of the postulated Svalbard
endemic S. svalbardensis to determine if this material corresponds to one of the
forms of S. cernua described in Flora Arctica USSR, which also is stoloniferous and
grows in humid places. According to Zhmylev, this Russian form of S. cernua is
distinctly different from S. svalbardensis, which thus probably should be
maintained as a Svalbard endemic.
4) Examination of a large material of the S. hyperborea/rivularis
complex revealed that the western European and Russian interpretations of this complex
have emphasized different morphological characters, resulting in different subdivisions of
the material. The Russian tradition has emphasized calyx and hair characters. More work
must be done in this complex to determine the number of species (e.g., what about S.
arctolittoralis?) and their circumscription. A project is currently being carried out
in Oslo, including chromosomal, morphological, and molecular analyses.