1.
Empetrum nigrum
Linnaeus, Sp. Pl. 2: 1022. 1753.
Empetrum eamesii
Fernald & Wiegand subsp.
hermaphroditum
(Hagerup) D. Löve;
E. hermaphroditum
Hagerup;
E. nigrum
subsp.
hermaphroditum
(Hagerup) Böcher;
E. nigrum
var.
hermaphroditum
(Hagerup) T. J. Sørensen
Branches
green, brown, or reddish, distally glabrous, eglandular or glandular, sparsely white-tomentose.
Leaves
divergent, becoming reflexed; blade 2.5-7 mm.
Flowers
unisexual or bisexual (plants synoecious, sometimes polygamous, or dioecious); sepals greenish pink becoming reddish purple.
Drupes
black, opaque, 5-10 mm diam.
Seeds
light brown, 1.5-3 mm.
2
n
= 26, 39, 52.
Flowering spring. Exposed, coastal bluffs and sphagnum bogs, windswept southern arctic and alpine tundra and open subalpine and boreal forests and mountain summits; 0-1900 m; Greenland; St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Nunavut, Ont., P.E.I., Que., Sask., Yukon; Alaska, Calif., Maine, Mich., Minn., N.H., N.Y., Oreg., Vt., Wash.; Europe; Asia.
All black-fruited plants of the genus in North America are here considered to be
Empetrum nigrum
in the broad sense. There is great variation within the species, and various names have been proposed. Boreal and arctic diploids (2
n
= 26, E. Hultén 1968) with unisexual flowers, dioecious plants, have been treated as
E. nigrum
, and tetraploids (2
n
= 52) with bisexual flowers, synoecious plants, as
E. hermaphroditum
.
Empetrum nigrum
is typified on European, dioecious, diploid plants, and in this strict sense, there has been a question whether the name should be applied to North American plants (Á. Löve and D. Löve 1959) in areas with synoecious tetraploids, where diploids were thought to be absent.
Dioecious, diploid, black-fruited crowberries are now well known from Maine, New Brunswick, Newfoundland, and Nova Scotia (J. Maunder, pers. comm.; P. Morisset, pers. comm.). There appears to be some ecological separation between the dioecious
Empetrum nigrum
and the synoecious
E. nigrum
; the dioecious plants in Newfoundland are reported to be replaced by the synoecious ones at higher elevations or in very exposed localities (J. Maunder, pers. comm.).
Dioecious plants have been long known in the Pacific Northwest (J. A. Calder and R. L. Taylor 1968) and Alaska (E. Hultén 1968), and diploids have now been confirmed for the Cascade Range, Washington; Prince Rupert, British Columbia; and the Kenai Peninsula, Alaska (V. Mirré 2004). Some of these western diploids have chloroplast DNA more closely related to South American accessions (diploid
Empetrum rubrum
) than to any Northern Hemisphere
Empetrum
investigated with chloroplast
trn
S-
trnf
M and
trn
S-
trn
G sequences (M. Popp et al., unpubl.). The nuclear sequence data show a more complex pattern wherein the alleles found in the South American accessions represent a subset of the alleles found in the Northern Hemisphere accessions (nuclear low copy RPB2 and RPC2 sequences).
Empetrum hermaphroditum
, a name in prominent usage, is typified on a Greenlandic, synoecious tetraploid, and this name and combinations of it have been applied to virtually all black-fruited synoecious plants in North America and wherever else black-fruited, synoecious crowberries are found (cf. Á. Löve and D. Löve 1959). In Europe, in addition to the diploids, there are synoecious tetraploids of
E. nigrum
.
V. Mirré (2004) concluded that tetraploid synoecious plants have arisen multiple times from different combinations of diploids resulting in a large pool of unstructured genetic variation. We conclude that synoecious tetraploids do not necessarily represent a distinct lineage and must, for the present, be subsumed by
Empetrum nigrum
as understood here.
The population of
Empetrum nigrum
reported from Montauk Point, Long Island, New York, has been extirpated (S. E. Clemants, pers. comm.).
