59.13 Potentilla L. (1753), Sp. Pl. 495. [BY]
Comments:
(1)
Genus concept. In the Russian drafts, Pentaphylloides, Comarum and Sibbaldiopsis
are treated as separate genera. This solution is retained here but should be discussed.
There are very good cladistic reasons to do it. If these groups are kept inside
Potentilla, we also have to include, e.g., Fragaria to avoid serious paraphyly.
A fourth group, included in Potentilla in Yurtsev's draft, must also then be
recognised as a separate genus - Argentina - and that has been done in this draft to
keep it consistent. (Elven)
(2)
Check-list of the genus Potentilla for the Panarctic Flora compiled by Boris Yurtsev
takes up 70 taxa of which 33 are proposed hybrids. In its present form the check-list
reflects taxonomy presented by Yurtsev (1984) in the Flora Arctica USSR and this
will be our starting point for further work. In general, we agree that the identity of
hybrids must be examined much more thorougly, but until we have more evidence for
their being or non-being (as hybrids), the names remain in the list [i.e., the original
draft]. Under the section Niveae, the species aggregates identified in the study on hair
and other characters have been incorporated. (Eriksen)
(3)
The decisions on Potentilla and Dryas (original drafts author: Yurtsev) will
exemplify how we are to proceed with the checklist throughout and perhaps also with
the Flora itself in the future, if we reach that stage. These are probably the most
important decisions we will have to make in the project altogether. I have therefore
summarised some of my general viewpoints here.
It is and may continue to be a problem that the final decision to start a
Panarctic Flora project was made in 1990 whereas the first guidelines for taxonomic
treatments were made as late as in 1999. There was a division of responsibilities in
that first phase. Databasing was (at least partly) to be a North American responsibility
whereas production of drafts of names and taxonomy was to be a Russian
responsibility. The drafts produced until Spring 1999, and partly also later, are
therefore naturally based on Russian traditions and principles, especially those of
Flora Arctica URSS.
Flora Arctica URSS and other Russian floras are very heterogeneous as to
how widely species are delimited and to application of the categories subspecies and
varieties. It has been, to a large degree, up to the single author (expert) how to apply
the principles. If we compare with western European and Hulténian treatments, some
authors of checklist drafts apply a wider species delimitation with little use of
subspecies (e.g., Skvortsov in Salix and Epilobium), some an intermediate
delimitation (e.g., Rebristaya, Tikhomirov and partly Korobkov), and some a
narrower delimitation (e.g., Yurtsev, Tzvelev and partly Petrovsky and Zhmylev). In
Flora Arctica URSS, this was even apparent within single families, e.g., in Poaceae
where Skvortsov's treatment of Festuca differed strongly from Tzvelev's treatment of
other genera.
We decided in Spring 1999 that we should proceed otherwise in the PAF
project by setting some general principles, one of them ($ 2a) as follows: "The
species concept(s) shall, as far as possible, be applied consistently throughout the
geographical areas treated and across different taxonomic groups and genetic and
reproductive situations." This leaves less freedom for the 'authors' than in some other
large flora projects, less than in Flora Arctica URSS and perhaps less than in Flora of
North America. It is, however, in accordance with the principles of Flora Europaea
and Flora Nordica, even if the practices in these floras also differed and differs.
Some other principles we decided on were based on a reluctance to accept a
priori theories as basic for the treatments until experimentally supported, especially
theories about hybridisation as a major source of novelty at all levels ($$ 9-11). This
point is specially important for the treatments of Potentilla and Dryas in this family,
for Poaceae (Tzvelev) and for parts of Saxifraga (Zhmylev). In Potentilla, $ 2c is
also relevant, stating that: "Apomictic aggregates shall be defined widely, in some
cases allowing for several narrowly defined agamospecies to be included in a
functional species".
The practical outcome of the principles and the other guidelines decided on in
Spring 1999 is that the original Russian drafts are input to the checklist process, to be
considered as the viewpoints of their authors, but they are to be modified and changed
according to the justified arguments of all the other participants in the PAF project. It
is improbable that any draft of any size will survive unchanged through that process.
A major problem is the language barrier. Russian literature is inaccessible to
most participants in the other countries for whom English is the common language of
communication. We can translate some small and important parts (as we have done,
e.g., in Dryas, Gastrolychnis and Papaver), but we have virtually no funding to do
such. It must therefore, by necessity, be the responsibility of the Russian contributors
to justify their viewpoints in English, or in a data format that can be 'automatically'
translated into some kind of English. It is not enough to say that "we prefer to do it
like this". And, the arguments must take into account the aims and principles we have
decided on (see Proceedings pp. 363-373). During the checklist production phase,
these arguments and justifications are best given as comments to be included in the
edited drafts for parts of the checklist. At the end, superfluous comments (where we
have reached some agreement) will be deleted. Remaining viewpoints will be edited
into shorter comments which will highlight the problems.
My general comments to the Potentilla draft are then as follows, with
reference to paragraphs in our taxonomic principles:
* The treatment is largely based on a model where extensive hybridisation
and stabilisation of hybrid products (by agamospermy) is assumed. Such processes
are active in Potentilla but very few of the arctic taxa proposed as such have been
investigated experimentally. Of the four proposed 'hybridogenous species' in the
North Atlantic area, two have been investigated experimentally and don't have the
parentage proposed (P. insularis and P. subquinata), the two others (P. protea and P.
scandica) are equally improbable and the latter has been found to be part of the
normal variation within a species (P. crantzii). This should be a warning against the
'hybridisation' approach as an a priori method in treatments of arctic Potentilla ($$ 9,
10, 11).
* Soják considers the leaf structure of paramount importance. Ternate and
pinnate leaves are 'primary' whereas digitate and semi-pinnate leaves and unstable
numbers of leaflets are indications of a hybrid origin. This is, however, proved to be
ecologically conditioned in several cases. Ternate leaves often become digitate under
favourable conditions and digitate leaves change into pinnate. The a priori
assumption underlying his model is therefore disproved by cultivation experiments
(and also by field observations) and should not be basic for the taxonomic treatment
(see the 'Species concept' part of the decisions).
* Many of the proposed hybridogenous taxa occur well outside the range of
their proposed parents, partly also very discontinuously without close connection to
their 'parents'. They are therefore inconsistent phytogeographically ($ 5).
* Agamospermy occurs in Potentilla and most probably also in many arctic
ones even if very little hard facts are available. The agamospermy is, however, not
total and we have to assume that large variation may appear after occasional
hybridisation. Due to the imperfect knowledge of the extent and effects of apomixis
in arctic Potentilla, we should apply a fairly wide species concept, probably wider
than in assumed sexuals. The futility of treating possible semi-agamospermic
aggregates as narrow species has been abundantly demonstrated in European
Hieracium and Taraxacum (the 'Ruderalia' group) and should not be repeated in
Potentilla ($ 2c).
What really is needed here is for someone to look critically at the variation in
the group without the a priori hypothethical 'spectacles' of Soják. (Elven)
(4)
(5)
The treatment is edited with all the taxa in Yurtsev's draft included in one way or
another, even if there are doubts concerning how to handle the many proposed
hybridogenous entities based on Soják's interpretation of the pattern of variation in
the genus. We have decided: (1) Not to accept entities as hybrids without strong
supporting evidence; and (2) Not to accept non-stabilised hybrids as entities for entry.
There is lack of such hard evidence in almost all cases in Potentilla; the evidence
given is mainly based on morphological intermediacy and on suppositions as concern
the paramount importance of some characters (e.g., ternate versus digitate and pinnate
leaves). In a few cases of Soják's proposed hybrids which have been tested (see
above), no evidence of a hybrid origin has emerged, and the same is strongly
indicated for others. Many other of Soják's cases are improbable for
phytogeographical reasons. The proposed hybridogenous entities are therefore treated
in different ways in the draft. Major entities with a significant distribution different
from their proposed parents are treated as species; entities cropping up here and there
or as very local within the range of their proposed parents are only listed after their
alphabetically first proposed parent. The final treatment in the checklist might be very
different from this edited draft. (Elven)
Two subgeneric levels - subgenus and section - are applied in Yurtsev's draft but our
general decision is to apply only one. Most of the species fall into only two
subgenera: Hypargyrium and Potentilla. The sections are more differentiating and
might be a better choice. Until later, both levels are kept in the draft. (Elven)
[Subg. Micropogon Bunge (1836), Suppl. Fl. Altaic. 40.]
Sect. Biflorae (Th. Wolf) Schiman-Czeika ***
B
***
59.13.1 Potentilla biflora Willd. ex Schltdl. (1816), Mag. Ges. Naturf. Fr. Berlin 7: 297.
S
T
[Described from E Siberia.]
2n=
14 (2x).
2nD
Löve & Löve (1975) list five counts, four as arctic; Zhukova & Petrovsky (1985).
G
RFE ALA CAN
Comments:
(1)
Hultén (1946) gives the year of the original publication as 1813. Check. (Elven)
[Subg. Hypargyrium Fourr. (1868), Ann. Soc. Linn. Lyon 2, 16: 371.]
Sect. Multifidae (Rydb.) Juz. in Kom. (1941), Fl. SSSR 10: 113.
B
*** Rydb. (1896), Bull. Torrey Bot. Club 1896: 262.
59.13.2 Potentilla pulchella R. Br. (1823), Chloris Melvill. 19.
S
T
[Described from Canada: Melville Island.]
2n=
28 (4x).
2nD
Löve & Löve (1975) list several counts for the collective species, all as arctic.
Comments:
(1)
The species name was first published as a nomen nudum by R. Br. in Ross (1819),
Voy. Disc, ed. 2, 193. (Elven)
(2)
Along with the circumpolar subsp. pulchella, subsp. gracilicaulis (P. pulchella var.
gracilicaulis) (Yurtsev et al. 1989: 86) is met with in Anabar-Olenyok, Kharaulakh,
Wrangel I., Alaska-Yukon, Central Canada and Baffin-Hudson Bay (more southern
parts), the distribution and status of the latter needs further exploration. (Yurtsev)
(3)
Therefore tentatively added to the draft as a separate entity. (Elven)
WARNING! The two subspecies might be omitted.
59.13.2.1 Potentilla pulchella R. Br. subsp. pulchella
S
2n=
2nD
G
NOR RUS SIB RFE ALA CAN GRL
Comments:
59.13.2.2 Potentilla pulchella R. Br. subsp. gracilicaulis (A.E. Porsild) Jurtz. (1989), Byull.
Mosk. Obshch. Ispyt. Prir., Biol. 94, 3: 86.
B
P. pulchella R. Br. var. gracilicaulis A.E. Porsild (1943), Sargentia 4: 48.
S
T
[Canada: Atkinson Point east of the Mackenzie Delta, leg. A.E. Porsild 3632.]
2n=
2nD
G
SIB RFE ALA CAN
Comments:
(1)
Porsild (1955) indicates a possible identity between this race and P. pulchella R. Br.
var. elatior Lange (1880), Consp. Fl. Groenl. 4. If this is proved, the range will
extend to Greenland and the separation between subsp. gracilicaulis and the type race
will become extremely obscure.
In autumn 2000 we have been through all the material in CAN and O from
the Canadian Arctic Archipelago. There is certainly some variation but not any clearcut pattern that fits the two subspecies. I therefore propose that we reduce the
'gracilicaulis' entity to synonymy in the next version of the checklist draft. (Elven)
59.13.2.3 Potentilla uschakovii Jurtz. (1988), Bot. Zhurn. 73, 11: 1613 [P. pulchella
R. Br. x P. subvahliana Jurtz.] - RFE
Comments:
(1)
Only reported in Yurtsev's draft from Wrangel I., as rare. Should probably be
considered a hybrid (and not a species) until we have available more
documentation. (Elven)
The Potentilla multifida aggregate (P. anachoretica, P. bimundorum, P. tergemina)
(1)
I am sceptical to acceptance of segregates in the P. multifida aggregate as species. I
would much prefer to treat them as more minor agamospecies within a collective P.
multifida. The same is the case with the non-arctic N Fennoscandian segregate
described as P. lapponica (F. Nyl.) Juz. (Elven)
59.13.3 Potentilla tergemina Soják (1964), Preslia 36: 26.
S
P. multifida auct., non L. (1753).
2n=
2nD
G
RFE*
Comments:
WARNING! Might be considered a possible agamotaxon within a more widely defined
P. multifida L.
59.13.4 Potentilla bimundorum Soják (1974), Casopis Národn. Mus. Odd. Pri. 141, 3-4:
195.
S
P. multifida auct., non L. (1753).
2n=
2nD
G
ALA CAN
Comments:
WARNING! Might be considered a possible agamotaxon within a more widely defined
P. multifida L.
59.13.5 Potentilla anachoretica Soják (1974), Preslia 46: 70.
S
P. czukczorum Jurtz. & Petrovsky, nomen nudum, in Jurtzev (1974), Prodl. Bot.
Geogr. SV Azii 61; P. arctica auct., non Rouy (***); P. multifida auct., non L.
(1753).
Comments:
(1)
A diploid karyorace, 2n=14, is recorded from the Chersky Range in the subarctic NE
Yakutia and may deserve the recognition at species level. All three types differ in
some details of ultrastructure of leaf pubescence (Eriksen, Yurtsev, in press).
(Yurtsev)
(1)
We need more information about the two varieties. Var. planiuscula seems to occur
as a rarity entirely within the range of var. anachoretica. Is it ecotypical? (Elven)
WARNING! Might be considered a possible agamotaxon within a more widely defined
P. multifida L.
59.13.5.1 Potentilla anachoretica Soják var. anachoretica
S
2n=
(1) 28 (4x). (2) 42 (6x). (3) 56 (8x).
2nD
(1) Erlandsson in Löve & Löve (1942b); Zhukova & Petrovsky (1971).
G
SIB RFE ALA
Comments:
(1)
Where is the documentation of the Alaskan occurrence? (Elven)
59.13.5.2 Potentilla anachoretica Soják var. planiuscula Jurtz. (1984), Fl. Arct. URSS 9, 1:
321.
S
2n=
2nD
G
RFE
Comments:
WARNING! Will be reduced to synonymy if not more convincingly documented as a
worthwhile entity.
59.13.5.3 Potentilla borealis Soják (1985), Willdenowia 15, 1: 167. [P. anachoretica
Soják x P. arenosa (Turcz.) Juz.] - RFE ALA. 2n=42, 56.
Comments:
(1)
Reported by Yurtsev from four regions and might be widespread enough to
deserve recognition. The hybrid hypothesis is, however, unsubstantiated by
experimental evidence. Another explanation of this and the forthcoming
'hybrids' is that they could be parts of a more widespread and variable
species. (Elven)
59.13.5.4 Potentilla petrovskyi Soják (1984), Cas. Nár. Muz. (Prague) 153, 2: 102
[P. anachoretica Soják x P. nivea L. s. lat.] - RFE ALA. 2n=28, 56.
Comments:
(1)
The parent from the section Niveae is to be identified. (Yurtsev)
(2)
Reported from four regions. Se comment under P. borealis. (Elven)
59.13.5.5 Potentilla tschaunensis Juz. ex Jurtz. (1984), Fl. Arct. URSS 9, 1: 317,
165. [P. anachoretica Soják x P. nivea L. s. lat.] - RFE ALA. 2n=28, 56.
Comments:
(1)
(2)
Potentilla tschaunensis differs from P. petrovskyi, besides the disposition of
leaflets (predominantly pseudopalmate versus mostly shortly pinnate), also in
the type of tomentum on petioles: floccose vs. crispate. (Yurtsev)
Similar variation is found within species elsewhere in Potentilla. Reported
from three regions. See comment under P. borealis. (Elven)
59.13.5.6 Potentilla czegitunica Jurtz. (1984), Fl. Arct. URSS 9, 1: 319, 196. [P.
anachoretica Soják x ?P. nivea L. s. lat. x ?P. uniflora Ledeb./subvahliana Jurtz.] RFE
Comments:
(1)
Reported from one region. See comment under P. borealis. (Elven)
59.13.5.7 Potentilla dezhnevii Jurtz. (1984), Fl. Arct. URSS 9, 1: 318, 166. [P.
anachoretica Soják x ?P. subvahliana Jurtz.] - RFE
Comments:
(1)
Reported from one region. See comment under P. borealis. (Elven)
59.13.5.8 Potentilla murrayi Jurtz. (1993), Bot. Zhurn. 78, 11: 80 [?P. anachoretica
Soják x P. subvahliana Jurtz.] - ALA
Comments:
(1)
This species differs significantly from P. dezhnevii in pubescence of petioles.
(Yurtsev)
(2)
Not examined by scanning electronic microscope. (Eriksen)
(2)
Reported from two regions. See comment under P. borealis. (Elven)
59.13.6 Potentilla lyngei Jurtz. & Soják in Jurtz. (1984), Fl. Arct. URSS 9, 1: 317, 160.
S
P. sericea L. var. dasyphylla auct., non Ledeb. (1830).
2n=
2nD
G
RUS GRL?
Comments:
(1)
Potentilla lyngei subsp. spissa Soják ined. (WEA: Svalb.?; G: E Greenl. (n/c)) may
represent a modification of P. lyngei s. str. (cf. also Eriksen & Nylehn, in press; see
also P. insularis). (Yurtsev)
(2)
Potentilla insularis has been tentatively moved from the hybrid complex of P. lyngei
to the P. arenosa aggregate due to combined morphological and genetic
investigations (Hansen 1998, Hansen et al. 2000, Hamre 2000). It probably belongs to
a separate form-group that also includes P. pedersenii and P. rubricaulis.
The Svalbard record of P. lyngei, included in Yurtsev's draft, is based on a
plant that fits much better with P. insularis (Hamre 2000). Svalbard (NOR) has
therefore been excluded. The same seem to be the case with the dubious Greenland
record of a separate subsp. spissa. (Elven)
59.13.7 Potentilla wrangelii Petrovsky (1977), Bot. Zhurn. 62, 5: 675.
S
2n=
2nD
G
RFE
Comments:
(1)
Very little seems to be known about this entity and it needs much further
documentation. (Elven)
WARNING! Must be better substantiated before acceptance.