Dryas integrifolia Vahl.
Mountain avens.
Rosaceae, rose family.
Skr. Nat. Hist. Selsk. Kjøbenh. 4, 2: 171. 1798.
Described from Greenland.
Subsp. integrifolia var. canescens Simm.
Dryas
octopetala L. var. integrifolia (Vahl) Hooker f.
Vegetative morphology. Plants shrubs; dwarf shrubs, or low shrubs; (2–)5–15(–17) cm high; not caespitose; with branched intertwined stems forming mats 10–100 cm in diameteron barren tundra. Taproot present (not often preserved), or absent (poorly developed lateral roots, developed along the branches, may be present on herbarium specimens). Caudex absent. Ground-level or under-ground stems horizontal; 5–10 mm wide. Aerial stems prostrate; obscured by stipules and petioles. Leaves distributed along the stems; alternate; simple (a contrast with other Arctic members of the family); marcescent. Stipules present; scale-like; 12–18 mm long; 1.5–2.5 mm wide; not sheathing; green (when very young), or brown (turning brown with age). Stipules hairy. Stipules hairs short-silky; apex acuminate. Petioles 1–10(–15) mm long; hairy; villous, or woolly, or hairs long-silky; hairs more than the diameter of the petiole. Petioles hairs spreading; straight, or wavy; rough. Leaf blade bases cordate (slightly), or truncate. Blades 5–22 mm long; (1–)2–4(–6) mm wide. Blades leathery; linear, or oblong, or lanceolate (narrowly triangular at least towards the apex); flat, or revolute (just at the margins or involving most of the leaf blade); veins pinnate. Blades secondary veins impressed into adaxial surface, protruding on abaxial surface (slightly). Blades adaxial surface without sessile glands; glabrous. Blades abaxial surface hairy. Blades abaxial surface hairs very dense. Blades abaxial surface tomentose (between the veins), or hairs long-silky (along the mid-vein). Blades abaxial surface hairs white, or translucent hairs; wavy; spreading. Blade margins entire, or crenate (slightly); glabrous, or with non-glandular hairs; with teeth toward the base (mainly). Leaf apices acuminate, or acute. Leaflets veins conspicuous.
Reproductive morphology. Flowering stems present. Flowering stems conspicuously taller than the leaves; without leaves; hairy. Flowering stem hairs woolly; simple. Flowering stems glandular hairs present (usually more non-glandular hairs present). Flowering stem hairs longer than the diameter of the flowering stem; white or translucent. Flowers solitary. Inflorescence not elongating as the fruit matures (the styles elongate, in solitary flowers). Flowers medium-sized, 5–15 mm in diameter or length, or large, more than 15 mm in diameter or length. Epicalyx absent. Calyx sepals 7–8; free; 3–9 mm long; 1.5–3 mm wide. Calyx green, or brown, or black; hairy (at the tips of the sepals); woolly (with conspiciuous black glandular hairs usually: some plants collected on Baffin Island lack the black glandular hairs on the calyx). Calyx hairs glandular; white or translucent (rarely), or brown, or black. Petals free; 7–11; white, or yellow (cream); ovate, or obovate; unlobed; 5–13 mm long; 5–10 mm wide. Stamens 40–70; filaments glabrous. Anthers yellow; subglobose; 0.15–0.25 mm long. Gynoecia superior. Carpels apocarpous; 20–40. Styles 3–5 mm long. Styles conical; basal portion with hairs at the base. Stigmas receptive surface at the end of an otherwise unmodified style. Fruit sessile. Fruit with calyx persisting; dry; an aggregate of nutlets; obovate; indehiscent. Fruit 2–5 mm long (without stigmas); brown, or straw coloured; hairy; surface appearing veinless (obscured by hairs). Styles modified and persisting (elongated to 1.5–2.5 cm; initially styles are intertwined and twisted, unwinding as the fruits mature); becoming plumose (becoming white, and fluffy from long hairs on the style).
Chromosome information. 2n = 18. 18 (2x). - Böcher and Larsen (1950 Greenland); Löve (1954b); Packer (1964 western Canada, perhaps 'sylvatica'); Elkington (1965 Greenland); Zhukova (1965a Chukotka as D. chamissonis, 1966 north eastern Asia, 1982 north eastern Asia, as D. chamissonis); Mosquin and Hayley (1966 northern Canada); Hedberg (1967 northern Canada); Packer and McPherson (1974 northern Alaska); Löve and Löve (1982a arctic Canada). Ploidy levels recorded 2x.
Distribution. Northern hemisphere distribution: North American (just crossing into Chukotka); Greenland, Canada, United States. Arctic. Range in the Canadian Arctic Archipelago widespread. Common. Arctic Islands: Baffin, Devon, Ellesmere, Axel Heiberg, Parry Islands, Cornwallis, Banks, Victoria, Prince of Wales, Somerset, King William, Southampton, Coats (Salisbury).
Ecology and habitat. Substrates: wet meadows (rarely, e.g. CAN 264266), depressions of low centre polygons (occasionally, e.g. CAN 74268), river terraces, tundra, slopes, ridges; imperfectly drained moist areas (rarely), or dry, or moderately well drained areas; rocks, gravel, sand, silt, clay; with low organic content.
Indigenous knowledge. Inuit names malikkaat, isuqtannguat,
isurramuat. The word malikkaat is used in Pangiqtuuq while
isuqtannguat, is used in Kinngait. According to their etymology, these
plants are called malikkaat because they follow the seasons. The word
isurramuat refers to the fact that they follow the path of the sun. These
plants are said to indicate the seasons: when summer is coming they fold out in
one direction and when winter is coming they fold in and twist in the other
direction (Ootoova et al. 2001).
The leaves may be called
qasilinnait, or atungaujat, and are possibly known as the plant
that numbs the tongue (Ootoova, 2001). Atungaujat in Igluik are leaves of
mountain avens. In some communities in South Baffin the term is used for gilled
mushrooms; in some communities in both North and South Baffin it refer to leaves
that seem to sprout individually right from the ground, that are reddish in
colour and shaped like willow leaves. These leaves are known as alatsaujat in
other communities.
Piluit: the dye and seeds of avens.
Notes. The common name, 'moutain avens' is used for the species
Dryas ccotopetala in northern Europe.
The flowers of Dryas are
heliotropic and face the sun as it moves across the horizon. The flower sepals
in bud often appear black from the many course hairs that may be
glandular-tipped. Occasionally these hairs are absent and the sepals appear
grey-green, see for example, Baffin Island, Camp Kungovik, J.D. Soper
125996, 15 July, 1929. CAN 74264.
A cold interval in the Early Holocene
is known as the Younger Dryas, after the genus Dryas that spread
southward with the frigid conditions. The trend was accentuated slightly before
13000 years ago when the northern hemisphere began to shift back toward full
glacial conditions in a shift that took place over about 200 years and resulted
in cold conditions that persisted for more than 1000 years. Younger Dryas
cooling was global in scale, causing mountain glaciers to expand well below the
present limits. The Younger Dryas suddently ended about 11,600 years ago. Oxygen
isotope measurements in ice cores reveal that the climatic shift took place
within just three years, most of it during a single year (Stanley 1999).
Porsild (1947) indicated that D. integrifolia in North America it is
by far the most common and widespread member of the genus and in postglacial
time has reoccupied nearly all land surface in the Arctic once occupied by ice.
It is an arctic-alpine species which within its main area is an ubiquitous
pioneer species in rocky and gravelly places such as river flats and screes. but
less common in the dwarf shrub heath where it cannot long survive competition
for space. Dryas integrifolia fruits abundantly, and its immature achenes
form an important food item for numerous species of small rodents and for
several species of birds.
Porsild (1947) stated that D. integrifolia
seems to be entirely lacking in ecotypes, an opinion that might be debated based
on specimens from the eastern Canadian Arctic Archipelago. He noted that D.
integrifolia from Greeenland, D. octopetala s.s. from Europe, and
D. drummondii from the eastern Canadian Rockies have long been grown
commercially, as well as in botanical gardens, where they have all preserved
their characteristics and there is little reason to expect that fundamental
characters such as the presence or absence of glands would be controlled by
ecological variables. He also noted that it would be of considerable interest to
grow many of the other taxa that have been recognized in the genus in
cultivation, but many of them are isolated in most inaccessible areas and fresh
seed material cannot easily be procured.
Juzepczuk (1920 in Fl. SSSR, X.
1941) provided a comprehensive treatment of the genus Dryas chiefly
dealing with Asiatic plants. Porsild (1947) wrote on the genus in North America
extending the treatment by Juzepczuk to areas in North America where that author
had few specimens to work with. These authors recognized within the genus
Section Notodryas Juz. that has leaves pointed at the base; petals
and sepals erect-spreading or quite erect during florescence and receptacle
flattened, species D. drummondii and D. grandis;
Section
Eudryas Juz., leaves mostly rounded, truncate or sub-cordate at the base;
petals and sepals spreading during florescence, receptacle convex.
Within
Eudryas they recognized three sub-sections:
Sub-section
Chamaedrifoliae Juz., leaves crenate or dentate in their entire length,
the upper surface deeply impressed over the secondary veins, wrinkled of almost
smooth, without punctiform glands, example species D. octopetala;
Sub-section Punctatae Juz., leaves incised-crenate in their entire
length, the upper surface deeply impressed over the secondary veins, wrinkled
with punctiform glands, example species D. punctata Juz.,
Sub-section
Tenellae Juz., leaves entire or dentate in the basal part only, or
minutely crenulate in their entire length, the upper surface scarcely or hardly
at all impressed over the seconday veins, smooth or slightly wrinkled, without
punctiform glands, example species D. intergifolia.
Porsild (1947)
and Hultén (1959) considered Dryas as an old holoarctic genus
particularly interesting for studies in phytogeography and phylogeny. Dryas
octopetala is thought to have once had a complete circumpolar distribution
reaching iNorth Americaerica from Alaska south to Colorado and east to
north-eastern Greenland. Hultén (1959) considered Dryas to be a
tertiary genus that early differentiated into three types, two closely related,
D. octopetala and D. integrifolia, and the third more
differentiated, D. Drummondii that occurs in western Continental North
America, and possibly a fourth, D. grandis that occurs in Eastern Russia.
He stated that both D. octopetala and D. integrifolia are probably
fairly old and must have existed before the glacial period. During the glacial
period southern isolated populations of D. octopetala also occurred in
Central Europe, in the Caucasus, in Japan and in the Rocky Mountains, where more
or less different races were developed and still remain isolated in most cases.
Considering the eastern Canadian Arctic Archipelago Hultén (1959)
stated that this is where D. integrifolia is presumed to have survived
the glacial period and to have hybridised with D. octopetala so strongly
that today only a remnant of the hybrid is left, while in eastern Greenland
D. octopetala still survives, although a large part of its population
apparently shows the hybrid influence of D. integrifolia in lacking
octopetala scales.
Hultén (1959) considered hairs, glands, and
scales on the leaves are very good characters for identifying the different
races within the D. octopetala complex, while the form of the leaves and
other characteristics used for that purpose he considered less reliable. He
described octopetala scales as long narrow more or less flat
brownish-colored tuft-like scales, built up of several rows of cells with white
hairs in their margins. The scales occur on the underside of the leaves on the
leaf mid-nerve and to a lesser extent on the lateral nerves. Hultén
(1959) commented that it is remarkable that octopetala scales which are
so significant for some taxa, can be missing where they would be expected and
occur where they are not expected. For example D. octopetala-like taxa
lacking octopetala scales occur in Alaska and in East Greenland.
Hultén (1959) opinioned that D. integrifolia is supposed to
have occurred in the Rocky Mountains, south of its present range and also in
eastern Asia westwards to Lake Bajkal, but was so strongly influenced by D.
octopetala there that only hybrids remain today, except in the north-eastern
corner of Asia where D. integrifolia still occurs. In unglaciated Alaska
and Yukon special races both of D. integrifolia (subsp. sylvatica
Hultén) and D. octopetala (subsp. alaskensis Porsild)
developed during the glacial period. There the areas of at least six different
entities (not counting D. drummondii) overlap and cross more or less
freely and can only more or less arbitrarily be distinguished from each other.
Cody (1995) provides a key to try and do so. Hultén (1959) provided a key
to taxa and hybrids that he recognized.
In the eastern Canadian Arctic
Archipelago, Hultén (1959) recognized D. integrifolia Vahl. subsp.
integrifolia x octopetala L. subsp. octopetala
citing specimens collected from Southampton Island and Prince Patrick Island but
nobody else appears to have recognized this combination.
Nordal et al.
(1999) held a workshop to discuss a proposed treatment of the genus Dryas
for the developing Checklist of the Panarctic Flora. Yurtsev (1997) recognized
15 species in the genus globally and of these nine reach the Arctic. The taxa
are mainly defined and delimited by characters from indumentum, glands
(presence/absence and types), and leaf shape, incision and structure. The
workshop provided a modified translation of the key given by Yurtsev (1997) with
hybrid combinations that he proposed removed. The discussions concerned the
interpretation of the morphological variation and its taxonomic significance,
especially the use of single characters and of the assumptions of hybridogenous
origins of taxa with intermediate features. No consensus was reached. The
conclusion was that here is an obvious need for modern analyses of both arctic
and non-arctic Dryas, involving both more extensive morphological
analyses, investigation of molecular markers, and further application of
eco-geographic methods.
The collection at CAN of more than 200 Dryas
specimens from the eastern Canadian Arctic Archipelago was examined, especially
for the ‘octopetala’ scales on the under surface of the leaves. The
four specimens referred to in the notes under D. punctata were included
in the survey. Some morphological variation was observed but until further study
no reason for recognizing more than one taxon in the area has been found and
that taxon is D. integrifolia.
There seems to have been much
‘hair splitting’ in some taxonomic treatments of Dryas. It may
be that a DNA study of circumpolar samples from the genus may show many
different cpDNA haplotypes as has been shown for Saxifraga oppositifolia
by Abbot et al. (2000) examined the cd-DNA restriction site variatioNorth
Americaong 548 plants sampled from 90 different populations from around the
circumpolar and circumboreal area and found 14 cpDNA haplotypes. Whether
morphological differences can be linked to DNA differences would still need to
be demonstrated. As Dryas is a member of the Rosaceae, a relatively
primative flowering plant family that is known to have variation in the number
of parts of the flower, it does not seem unusual that small variations in leaf
surface characters occur and that some of these have been isolated in localized
areas given the glacial history of the genus. Perhaps ‘octopetala
scales’ are like freckles that are found on certain pale skinned members of
the human race, although never on others. As the presence or absence of freckles
is not considered taxonomically important in humans, it is tempting to consider
the presence or absence of the octopetala scales, or punctiform glands, in
Dryas about as significant until proved otherwise.
Illustrations. • Plant habitat. Dry Dryas mats (at markers) on dry, rocky tundra. Plants with inflorescences that are beginning to set seed. Ellesmere Island, near John Richardson Bay 80°21'N, 71°21'W. Aiken 98–051. CAN. Photograph by Mollie MacCormac. • Plant habit. Lush flowering plants growing in a sheltered gully, N.W.T., Banks Island, Sachs Harbour. 27 July 1981, J.M. Gillett 18857. CAN. • Close-up of bud. Flower in bud. Note reddish black hairs on the sepals. These possibly aid in warming the developing flower. Banks Island in Aulavik National Park, near green cabin, June 29, 1999. Aiken. CAN. • Close-up of plants. Flowers in bud, flowering and past flowering. Banks Island in Aulavik National Park, near green cabin, 13 July, 1999. Aiken. 99–064. CAN. Scale bar in cm. • Close-up of flowers. Prostrate woody shrub in flower. N.W.T. Banks Island, Sachs Harbour, 27 July 1981, J.M. Gillett 18857. CAN. • Fly pollination. Fly actively foraging on Dryas flower. that is almost completely open. Nunavut, Baffin Island, Soper River Valley. Aiken 2002. No voucher. • Flowers with and without petals. • Surface view of leaves. Upper leaf: note hairy stipules at the base of the petiole and deep green upper surface to the leaf. Lower leaf showing light green "duffle-coated undersurface. Aiken 2002. Leaves in front of NRI, Iqaluit. • Close-up of flower. Flower approximately 1 cm in diameter after the petals have been shed. The inner surface of the sepals is pale green, there is a ring of numerous anthers, and twisted styles in the center. Banks Island in Aulavik National Park, 3 July, 1999. Aiken. 99–064. CAN. • Plant in fruit. Plants with developing fruits. Note narrow, almost entire leaves, glandular hairs on calyx and elongating flower stalk and styles after flowering. N.W.T., Tuktoyaktuk, 21 July 1981, J.M. Gillett 18727. CAN. • Habitat. Soil polygon landscape in Northern Arctic Tundra Zone, with Dryas (octopetala) in all the cracks. Norway: Svalbard, Siklarhallet. Aug. 1997. Photographed by R.Elven. • Arctic Island distribution.
Cite this publication as: ‘S.G. Aiken, M.J. Dallwitz, L.L. Consaul, C.L. McJannet, L.J. Gillespie, R.L. Boles, G.W. Argus, J.M. Gillett, P.J. Scott, R. Elven, M.C. LeBlanc, A.K. Brysting and H. Solstad. 1999 onwards. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 29th April 2003. http://www.mun.ca/biology/delta/arcticf/’. Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993, 1995, 2000) should also be cited (see References).
