ISSN 1188-603X

No. 389 February 21, 2008 Victoria, B.C.
Dr. A. Ceska, P.O.Box 8546, Victoria, B.C. Canada V8W 3S2


From: Ken Marr, John Pinder-Moss and Richard Hebda c/o  []

Michael Cheney died suddenly of a massive stroke on Friday, November 2, 2007.  Our friendship with Mike began in August 2002, when he emailed to Ken Marr an image of a plant that he had been unable to identify and asked for help.  Since that initial contact several times each year Mike has phoned or emailed questions regarding specific plants that he was trying to identify, recommendations for plant taxonomy texts, identification keys, and recommended readings to understand molecular systematics.  There are more than 40 email messages from him in Ken's "Inbox".

 In the spring of 2003 he emailed Ken images of an unknown Apiaceae that he had been trying to identify for more than a year.  This plant turned out to be Oxypolis occidentalis Coult. & Rose, a species new to Canada and almost certainly native to the Queen Charlotte Islands (Haida-Gwaii).  An article regarding this species has been accepted by the Canadian Field Naturalist (Cheney & Marr in press).  Mike made many collections of both native and introduced species that were first records for the QCI and donated his specimens to the herbarium of the Royal British Columbia Museum in Victoria,  BC (V).  Occasionally when he encountered a plant lacking flowers or some other critical morphological character he dug it up and brought it to his home in order to make further observations as the plant grew. 

In the last couple of years or so, he became interested in the history of the Haida Gwaii landscape and understanding how long plants like Oxypolis had been there. We were contemplating strategies for taking cores or soil profiles in the most promising sites in search of ancient pollen grains.

Mike was an Old Testament scholar, on the faculty of Athabasca University.  Michael Cheney received his PhD in Old Testament Exegesis, and is the author of Dust, Wind and Agony: Character, Speech and Genre in Job an exploration of the Book of Job and its relationship to Egyptian and Mesopotamian literature, published by Almqvist and Wiksell in 1994,

Because he was not formally trained as a botanist, initially we checked his identifications, but soon realized that his were always correct.  In September 2007 Mike together with two others published a checklist of "The Vascular Plants of Haida Gwaii" (Cheney et al. 2007).  Mike’s involvement with the Invasive Plant Council of British Columbia resulted in his production of DVD that documented his efforts to control some of the large invasive "Knotweed" species by spraying them with seawater. [For more information on this DVD contact .]

Mike was a valued friend for many botanists who did not have the resources themselves to reach the Queen Charlotte Islands, a place whose biota are of significant interest due to the isolation of the archipelago and the great likelihood that some of their terrain escaped the last glaciation. (i.e. ice free during the late Pleistocene glaciations).  If it was within his reach, Mike could be counted on to make collections of specimens or tissue for DNA analysis.  Our own research on the phytogeography of Oxyria digyna benefited greatly from the tissue collections that he made.  Only a few days ago we mailed tissue samples of a rare reedgrass, Calamagrostis sesquiflora that Mike collected at Takakia Lake, to researchers at the Smithsonian Museum of Natural History who are undertaking a phylogenetic study of the genus in North America.

During his visits to our herbarium we appreciated greatly his easy going nature and sense of humour.  Thanks to his passion for botany, the botanical community of North America has benefited greatly from Mike’s enthusiasm and intense natural curiosity.  As a colleague and friend he will be greatly missed.


Cheney, M. &  K. L. Marr.  in press.  Oxypolis occidentalis from the Queen Charlotte Islands, British Columbia.  A new species for Canada.  Canadian Field Naturalist.

Cheney, Mike, Patrick Bartier, & Barb Johnston. 2007. The Vascular Plants of Haida Gwaii. Gwaii Haanas National Park Reserve and Haida Heritage Site, Skidegate, British Columbia.  23 p. Available from Patrick Bartier e-mail:


From: Wilbur L. Bluhm [], Originally published in the Bulletin of the Native Plant Society of Oregon, Vol. 34 (2001) No. 3, page 36.

Ninety-nine percent of the annual commercial crop of filberts, or hazelnuts, Corylus avellana, in North America is grown in the Willamette Valley of Oregon. Nuts, foraged by birds and squirrels, are often dropped or buried beyond the boundaries of many C. avellana orchards. As a result populations of C. avellana and the native C. cornuta var. californica are commonly interspersed.

It can be difficult to distinguish the two species using the commonly available keys, which often use the differing involucre characteristics. Many plants, however, of both species do not fruit outside of cultivation. Further, characteristics of Willamette Valley plants appear to sometimes differ from descriptions in the keys.

The following comparison of the two species was developed with the assistance of Dr. Shawn Mehlenbacher, Professor of Horticulture, hazelnut breeder at Oregon State University, and Dr. Kenneth Chambers, Professor of Botany emeritus, Oregon State University.

Plant Characteristic

 Corylus cornuta var. californica

Corylus avellana

Winter Buds

 silvery in fall; appressed puberulent to villous or hirsute; oval; mostly obtuse to acute

bright green in fall; mostly glabrous, puberulent on margins; oblong to oval; acute

Stem, Leaf, and Petiole Hairs [Hairs diminish as season progresses]

whitish, hispid (tend to be prickly, will prick human skin); tend to be appressed or forward pointing; glandular hairs often mixed with hispid hairs, especially on leaf petioles

glandular, bristly, glandular hairs often mixed with finer puberulence

Leaves Stipules

often appearing bi-serrate or bi-dentate persist into fall during summer

more or less evenly serrulate drop during spring, or, mostly,


earlier than C. avellana

leaves remain green longer than with C. cornuta var. californica

Catkin Peduncles

short, almost sessile

longer, from sessile to c.1 cm

Catkins per Cluster

1 to 2

commonly more than 1 or 2

Pollen Release

3 months later than C. avellana

 starts in December

Pollination (female flower receptivity)

generally during March


Nut Involucre

 nut enclosed c.1.5-2.5 cm, with bristles (like nettles)

nut not enclosed beyond its end in cv. ‘Barcelona’; Turkish cvs. have long clasping husks; cvs. ‘DuChilly’, ‘White Lambert’,and others have tubular husks

Hybridization between C. cornuta var. californica and C. avellana is unlikely to occur. Although C. cornuta var. californica is receptive of C. avellana pollen its female flowers are later in the season and would rarely receive C. avellana pollen. C. avellana is not receptive of C. cornuta var. californica pollen. C. avellana cultivars hybridize with each other.


From: Reidar Elven (Oslo) and David F. Murray (Fairbanks)

[This article is based on the authors’s treatment of Potentilla for the Flora of North America project. The authors would gratefully acknowledge your comments.]

Potentilla nivea is a Linnaean name founded, it was long thought, on plants from northern Scandinavia. Initially P. nivea was applied to potentillas with 3-foliolate leaves (sometimes 4–5-foliolate) having a dense white tomentum over the abaxial leaf surface. Beyond that the use of the name is anything but simple and straight forward, and some historical background is necessary.

A major revision of the Linnaean species concept occurred when Juzepczuk (1941) and Hultén (1945) separated from P. nivea those species with stiff, spreading hairs on the petioles (P. arenosa (Turcz.) Juz., P. kuznetzovii (Govor.) Juz., P. chamissonis Hultén), which left P. nivea a species comprised of plants with only soft floccose petiole hairs.

Hultén, in his revision (1945), annotated a specimen of P. nivea in the Linnaean herbarium from northern Sweden as his P. chamissonis (stiff, spreading hairs) assuming the other specimen to be P. nivea s. str. (floccose hairs). He (1968b) later revised his taxonomy of P. chamissonis and accepted the name P. hookeriana Lehm. for a species with straight verrucose petiole hairs and reassigned his amphi-Atlantic P. chamissonis to that species as  P. hookeriana subsp. chamissonis (Hultén) Hultén. He assumed subsp. hookeriana to encompass western North America and Asia; he accepted both P. hookeriana subsp. hookeriana and subsp. chamissonis for northwestern North America.

Soják (1989) also studied the Linnaean specimens and concluded that the second one, assumed by Hultén to be P. nivea s. str., actually belonged to P. arenosa and speculated that it had been received by Linnaeus from Gmelin from Siberia. If true, this means that none of the Linnaean specimens correspond to P. nivea as that name had been used for European plants for more than 200 years!

Soják then adopted the name P. prostrata Rottb. 1770 for what had been called P. nivea, based on Greenland material, and named the European plant in the Linnaean herbarium P. prostrata subsp. floccosa Soják. This treatment was not well received as it turned established usage on its head. See for example Cody (1996) in which the long accepted name P. nivea was now applied to something entirely different--what was being called P. hookeriana-- and what had been understood as P. nivea was now given the very unfamiliar name P. prostrata. Although Soják had a legitimate point to make, a canon of the International Code of Botanical Nomenclature—stability—had been, if not violated, roughed up a bit.

Thus Eriksen et al. (1999) proposed to conserve the name P. nivea as traditionally used with a neotype from northern Sweden. The proposal was accepted by International Botanical Congress in Vienna 2005 (McNeill et al. 2006) in the nomenclature sessions where such matters are decided. Potentilla nivea is now the correct name for the European (and Greenlandic) species with floccose petiole hairs. This was accepted by Soják (2004) who had reconsidered and proposed anew that the Greenland P. prostrata is a hybrid P. chamissonis x nivea.

Yurtsev (1984) decided that the Beringian plants with floccose petioles actually consisted of two species: P. nivea s. str. and P. crebridens Juz., and within that latter species he recognized a northern subsp. hemicryophila Jurtz. This subspecies was reported by him as widespread in Alaska, together with P. nivea.  Yurtsev (1984) also considered P. nivea s. str. as restricted to non-arctic Europe (and perhaps Greenland) and the plants from Russia, Siberia and most parts of North America as P. nivea subsp. mischkinii or P. mischkinii, which Soják (2004) considered a synonym of P. prostrata, i.e., P. chamissonis x nivea.

Our questions, then, when studying specimens prior to a treatment of this group for the forthcoming volume of Flora of North America, were: (1) Are there two distinct species with floccose petiole hairs in Beringian North America, viz., P. nivea and P. crebridens (subsp. hemicryophila)? (2) How does the Beringian American P. nivea (P. mischkinii sensu Yurtsev, P. prostrata sensu Soják) relate to the European or amphi-Atlantic P. nivea s. str.? (3) Is the correct name for the Beringian plants with petioles having straight-hairs P. arenosa, P. hookeriana, or perhaps P. chamissonis? (4) Is there one (arenosa / hookeriana) or are there two (also chamissonis) straight-haired plants?

Morphological variation

The material can be divided very clearly into two major groups: one with floccose petiole hairs and one without. Some intermediates are found, but such plants are also found throughout northern Asia, northern Europe, Greenland, and other parts of North America, and they are interpreted by us as hybrids not deserving formal taxonomic recognition and rank. We do not, therefore, accept Soják's P. prostrata or Yurtsev's P. mischkinii as independent hybrid species.

In the beginning we did not see two Beringian species with floccose petiole hairs (i.e., P. nivea and P. crebridens), but we quickly had to revise our opinions. The specimens were easily placed into two piles, following the diagnostic characters given by Yurtsev (1984) and Soják (2004), see key below. Among well developed plants, we have not seen a single one we could not assign with certainty, that is, with no intermediates. We, therefore, accept P. crebridens (subsp. hemicryophila)  in addition to P. nivea for Beringian America. This is also supported by the chromosome numbers reported: P. crebridens is tetraploid (2n = 28), whereas P. nivea is a variable high polyploid (2n = 49, 56, 63, 70).

Some slight morphological differences are found between Beringian and Atlantic P. nivea (Elven in Aiken et al. 2007), which is congruent with molecular differences (Eriksen & Töpel 2005). The high and variable ploidy levels suggest that P. nivea has a complicated (polyphyletic and polytopic) evolutionary background, inasmuch as different combinations of parental genomes may have participated in the Atlantic plants on one hand and the Beringian plants on the other. Yurtsev's (1984) supposition that the Atlantic and Beringian plants were different is thus reinforced by independent sources. However, we have not yet found morphological differences distinct enough to formaliy recognize two races.

Beringian plants having leaf petioles with straight hairs are fairly uniform (except for presumed hybrids) and consistently different from plants of southern arctic parts of eastern Canada, Greenland and northern Europe. Potentilla chamissonis is distinguished from P. arenosa / hookeriana by the absence of a underlayer of short stiff or crisped hairs beneath the long, straight verrucose hairs. In a study of the arctic Canadian material (Elven in Aiken et al. 2007), plants corresponding closely with the European concept of P. chamissonis were found in southern Greenland and southeastern parts of the Canadian Arctic, north to Devon Island and to west of Hudson Bay. The plants in northern Greenland, Ellesmere Island and westwards, corresponded to the Beringian plants. Our conclusion is that "chamissonis" and "arenosa / hookeriana" represent two largely allopatric but closely related races, i.e., subspecies, of one species. The correct name of this species has been resolved fairly recently.

The Siberian name P. arenosa (Turcz.) Juz. belongs, without doubt, to our taxon, but is an older name available? This name has priority at the rank of species from 1941. The North American (Rocky Mountains) name P. hookeriana has priority from 1849 and would be the correct name if it is indeed the same as our species as assumed by Hultén (1968b) and many subsequent authors.

The type of P. hookeriana ("Amer. septentr. R Mount", leg. Burke, Herb. Lehmann PR 378171 holotype) is, however, more or less 5-foliolate and deviates in other features (Soják pers. comm. and 1996). Soják (1996) considered P. hookeriana a hybrid species from P. arenosa x P. bimundorum, the same as P. rubricaulis Lehm. 1830. We concur in the view that P. hookeriana most probably is a hybrid between species of sect. Niveae and sect. Pensylvanicae but not necessarily the same combination as in P. rubricaulis.

In any case, this removes P. hookeriana as a possible name for our species in the P. nivea group; the correct one is then P. arenosa with two subspecies: subsp. arenosa in Beringian North America (and Asia) and P. chamissonis in the amphi-Atlantic regions, recombined as P. arenosa subsp. chamissonis in Murray & Elven (2007).

With respect to the key below, note that styles in Potentilla are loosely attached to the achenes, mostly subterminal or in sect. Anserinae distinctly lateral. Styles wither and fall off from the achenes at maturity so they must be observed on late-flowering material. The styles are either tubular, i.e., of equal width from base to top, or narrowly conical, i.e., broadening towards the base; either smooth at the base or glandular-papillate.


1.   Petioles with short tomentum of floccose hairs; central leaflet not distinctly stipitate   

      2. Epicalyx bractlets elliptic or lanceolate, nearly as broad as sepals; styles with several distinct basal papillae; leaflets not overlapping, central leaflet with 3–5 well separated teeth per side, upper surface not densely hairy (green), base cuneate ……………………………………………………………………………………                      P. nivea

      2. Epicalyx bractlets linear, much narrower than sepals; styles with few basal papillae; leaflets overlapping, central leaflet with 4–8 approximate teeth per side, upper surface mostly densely hairy (gray), base broadly cuneate                                                          
                                                          P. crebridens
subsp. hemicryophila

1. Petioles without floccose hairs, with upper layer of long straight verrucose (50x        
    magnification) hairs; central leaflet distinctly stipitate                       P. arenosa

      3. Petioles with lower layer of short stiff or crisped hairs
                                                                               P. arenosa subsp. arenosa
      3. Petioles without lower layer of short hairs
                                                                         P. arenosa subsp. chamissonis


Potentilla nivea is widespread in northern and western North America, with a range nearly continuous from the Bering Strait eastwards to Greenland and reaching southwards in the western Cordillera to Montana, Wyoming and Colorado (for the southern relative P. holmgrenii, see Murray & Elven 2007). The transition between the eastern and western morphs takes place west of Hudson Bay; plants from Quebec, southeastern Nunavut and southern Greenland are indistinguishable from European (and type) plants.

Potentilla crebridens subsp. hemicryophila is strictly Beringian in North America, restricted to Alaska and northern and western parts of Yukon Territory. The other part of its range is Beringian Asia.

Potentilla arenosa subsp. arenosa is widespread throughout the northern parts of North America from Alaska to northern Greenland. It is replaced by subsp. chamissonis in southern Greenland and eastern parts of arctic Canada north to Baffin and Devon islands and west to the west coast of Hudson Bay. The occurrence of P. arenosa south of Yukon is unresolved; we have seen a few specimens, perhaps subsp. arenosa, from British Columbia and Alberta. It is widespread in Asia westward to northeastern European Russia.


Potentilla arenosa (Turcz.) Juz. in Kom., Fl. URSS 10: 137. 1941. – Basionym: P. nivea L. var. arenosa Turcz., Bull. Soc. Imp. Naturalistes Moscou 16: 607. 1843. Described from southeastern Siberia: Transbaikal.

Potentilla arenosa (Turcz.) Juz. subsp. arenosa. – P. nivea sensu Soják 1989, non L. 1753 emend. Eriksen et al. (1999). – P. hookeriana auct., non Lehm. 1849. – P. nipharga Rydb., N. Amer. Fl. 22: 332. 1908. Described from northwestern Canada: Mackenzie District, Fort Good Hope on the Mackenzie River, leg. I.S. Onion (NY). – P. nivea sensu Soják var. nipharga (Rydb.) Soják, Candollea 44: 751. 1989.

Potentilla crebridens Juz., Bot. Mater. Gerb. Bot. Inst. Komarova Akad. Nauk SSSR 17: 218. 1955. Described from southeastern Siberia: Angara Mts, Irkut River.

Potentilla crebridens Juz. subsp. hemicryophila Jurtz., Fl. Arct. URSS 9(1): 318, 169. 1984. Type: Russian Far East: west Chukotka, "montes Anjuenses, systema fl. Bolschoi Keperveem ad fontes fl. Koralveem", 23.06.1966, leg. P. Zhukova & V. Petrovsky 66-28 (2n = 28) (LE) holotype. – P. matsuokana Makino subsp. hemicryophila (Jurtz.) Soják, Candollea 44: 752. 1989.

Potentilla nivea L., Sp. Pl. 499. 1753 [nom. cons.]. Type: north Sweden: Torne Lappmark, Abisko area, Latnjajaure, leg. B. Eriksen 620 (GB) neotype [typ. cons.], designated by Eriksen et al., Taxon 48: 165 (1999). – P. prostrata Rottb. subsp. floccosa Soják, Candollea 44: 751. 1989. Type: France: Hautes-Alpes, Le Lautaret, ŕ-Prime-Messe, 1909, leg. Faurie (PR) holotype. – ?P. mischkinii Juz. in Pojark., Fl. Murmansk. Obl. 4: 323, 76. 1959. Type: northwest European Russia: Murman area, "montes Chibinenses in declive meridionali Poatschvumtschorr ...", 27.07.1946, leg. B. Mischkin 111 (LE) holotype. – ?P. nivea L. subsp. mischkinii (Juz.) Jurtz., Fl. Arct. URSS 9(1): 173. 1984.


Aiken, S.G. et al. 2007. Flora of The Canadian Arctic Archipelago.

Cody, W.J. 1996. Flora of the Yukon Territory. NRC Research Press, Ottawa. 643 p.

Eriksen. B., Jonsell, B. & Nilsson, Ö. 1999. (1394) Proposal to conserve the name
     Potentilla nivea
(Rosaceae) with a conserved type. – Taxon 48: 165–166.

Eriksen, B. & Töpel, M.H. 2006. Molecular phylogeography and hybridization in
     members of the circumpolar Potentilla sect. Niveae (Rosaceae). – Amer. J. Bot.
     93: 460–469.

Hultén, E. 1945. Studies in the Potentilla nivea group. – Bot. Not. 1945: 127–148.

Hultén, E. 1968a. Flora of Alaska and neighboring territories. A manual of the
     vascular plants.
– Stanford Univ. Press, Stanford.

Hultén, E. 1968b. Comments on the flora of Alaska and Yukon. – Ark. Bot., ser. 2,
     7, 1: 1–147.

Juzepczuk, S.V. 1941. Potentilla. Pp. 78–223 in: Komarov, V.L. (ed.), Flora URSS
– Moscow & Leningrad.

McNeill, J. et al. 2006. International code of botanical nomenclature (Vienna Code).
     – Regnum Veget. 146.

Murray, D.F. & Elven, R. 2007. A new species and two new combinations in
sect. Niveae (Rosaceae). – J. Bot. Res. Inst. Texas 1: 811–814.

Rydberg, P.A. 1908. North American Flora. 22.4. Rosaceae (pars). – New York
     Botanical Garden, New York.

Soják, J. 1989. Notes on Potentilla (Rosaceae). VIII. P. nivea L. aggr. – Candollea
     44: 741–762.

Soják, J, 1996. Notes on Potentilla (Rosaceae). XIV. Type specimens in the
     Lehmann herbarium. – Preslia 68: 97–124.

Soják, J. 2004. Potentilla L. (Rosaceae) and related genera in the former USSR
     (identification key, checklist and figures). Notes on Potentilla XVI. – Bot. Jahrb.
     Syst. 125: 253–340.

Yurtsev, B.A. (ed.) 1984. Flora arctica USSR. IX, 1. Droseraceae–Rosaceae. –
     Nauka, Leningrad.

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