Empetraceae A.F. Gray
Crowberry family.
Empetraceae, crowberry family.
Vegetative morphology. Plants shrubs; dwarf shrubs, or low shrubs; 5–10(–30) cm high; prostrate, matted, freely branching, evergreen, with trailing branches. Ground-level or under-ground stems not developed horizontally or vertically (no rhizomes or stolons, but branches are usually prostrate). Aerial stems prostrate, or ascending; with glandular hairs; sparsely hairy, or densely hairy; stem hairs spreading, or erect. Branches epidermis flaky (older stems). Leaves distributed along the stems; alternate; simple; evergreen. Petioles absent (leaf blade attentuate). Leaf blade bases attenuate. Blades 2–6 mm long; 0.5–1 mm wide. Blades spreading, or divaricate; leathery, or succulent (deeply furrowed on the lower side, the groove more of less closed outside by the marginal pubescence, seeming to form a central longitudinal cavity so that the leaf seems to be rolled); straight; linear; revolute (hollow); with inconspicuous veins. Blades secondary veins flat on adaxial surface, protruding on abaxial surface. Blades adaxial surface glabrous, or hairy. Blades adaxial surface hairs glandular. Blades abaxial surface hairy. Blade margins entire; with glandular hairs. Leaf apices acute, or obtuse.
Reproductive morphology. Plants monoecious, or dioecious, or bisexual. Flowering stems absent. Flowering stems with leaves (single flowers are on short shoots that arise laterally from the main axis and bear only scale leaves below the flower). Flowers solitary (in leaf axils). Bisexual spike(s) with empty bracts at the base (1 or more). Flowers small, less than 5 mm in diameter or length; actinomorphic. Perianth present (as tepals). Calyx sepals 3; free; 0.2–0.3 mm long (tiny); 0.08–0.12 mm wide. Calyx green (green at the base), or purple (towards the apex); petaloid; without sessile glands; glabrous. Petals free; 3; purple; 1–2 mm long. Flowers unisexual (subsp. nigrum), or bisexual (subsp. hermaphroditum). Stamens 2. Anthers ovoid (without appendages); 0.6–0.8 mm long. Nectaries absent. Gynoecia superior. Carpels syncarpous; (2–)4–9. Ovaries subglobose; glabrous. Styles variable, reflexed; partially fused. Placentation axile. Ovules 2–5. Fruit sessile. Fruit with calyx persisting; fleshy; a drupe; spherical; indehiscent. Fruit 3–8 mm long; 3–8 mm wide; black, or purple, or blue; glabrous; surface appearing veinless. Seeds 2–9; 1.6–1.8 mm long; brown; with surfaces verrucose.
Distribution. Northern hemisphere distribution: circumpolar; Greenland, Canada, United States, Eurasia, Norden.
Indigenous knowledge. Inuit name, paurngait.
Notes. The two European taxa, treated as subsp. nigrum and
subsp. hermaphroditum in Flora Europaea, by Tutin, are often
treated as separated species, largely because of their difference in chromosome
number; but the correlation between number and reproductive pattern, though
good, is not perfect (the latter being possibly susceptible to environmental
influences), and the differences in vegetative characters show some overlap.
Tzvelev (2001) recognized six subspecies within E. nigrum. Three of
them are restricted to Beringian areas: subspp. androgynum,
sibiricum and stenopetalum. Subspecies hermaphroditum is
widely amphi-Atlantic whereas a subsp. subholarcticum mainly replaces
subsp. hermaphroditum from Polar Ural throughout Siberia and Far East to
Northern Canada. Elven has personal knowledge of four of these ('nigrum',
'androgynum', 'hermaphroditum' and 'subholarcticum') and
finds them very difficult to separate consistently. Thus, he is very reluctant
to accept several subspecific taxa without a thorough documentation, especially
as at least one of them seems not to have been published at the level of
subspecies. As no-one else recognises the six subspecies, justification for
doing so must come from Russian botanists.
In north easternorth
Americaerica, Löve (1960) chose a different approach. She treated the
easterNorth Americaerican and arctic plants as different from the European E.
nigrum s. str. She recognized E. eamesii Fernald and Wiegand (Rhodora
15: 215, 1913) with three subspecies: (i) the non-arctic subsp. eamesii,
(ii) subsp. atropurpureum (Fernald and Wiegand) D. Löve, Rhodora,
62: 289, 1960, and (iii) the circumpolar subsp. hermaphroditum. This
approach is not reflected in Tzvelev's account. At species level E.
eamesii (1913) has priority before E. hermaphrodictum (1927).
Tzvelev's key to the taxa entered in the Flora of the Russian Far East as
roughly translated by David Murray follows:
1a. Current year's branches with
only very short glandular hairs; older branches glabrous or covered with remains
of glandular hairs. . . . . . . . . . . . 2
1b. Current year's branches,
except for short glandular hairs, more or less covered by longer flexuose hairs,
normally forming a thin tomentum. . . . . . . . . . . 3
2a. Plants
monoecious, almost always only with hermaphrodite flowers. Leaves usually
elongate-linear. - E. subholarcticum
2b. Plants dioecious, almost
always with unisexual flowers. Leaves usually linear. - E.
stenopetalum
3a. Plants monoecious, almost always only with hermaphrodite
flowers. Fruits black. - E. androgynum
3b. Plants dioecious, almost
always only with unisexual flowers. . . . . . . .4
4a. Leaves (5) 6–9 mm
long. - E. albidum
4b. Leaves 4–5 (6) mm long. . . . . . . . . .
. . 5
5. Fruits black. Leaves usually linear. - E. sibiricum
5.
Fruits red. Leaves usually elongate-linear. - E. kardakovii
The
entities 'subholarcticum', 'stenophyllum', 'androgynum',
and 'sibiricum' are among the ones included in Tzvelev's draft for the
Panarctic Flora (Tzvelev 2001).
In 2001, when Elven and Murray tried to
apply this treatment to Alaskan material (Alaska) where at least subsp.
subholarcticum and possibly subsp. sibiricum should occur,
according to Tzvelev's draft about half of the investigated specimens fell into
'subholarcticum', a significant group into 'sibiricum', a
similarly large group into 'androgynum', and a very significant group
combined characters across the criteria given by Tzvelev. Elven and Murray
concluded that there is probably significant taxonomic variation, but that the
current treatment by Russian botanists is unsatisfactory and does not adequately
fit the observed variation. The system given for the arctic north eastern Asian
(and Alaskan) variation, is virtually a two-character system of sex distribution
and current year's twig indumentum. In northernorthern Europe, the correlation
between ploidy level and flower sexuality, unisexual ('nigrum' s. str.)
versus hermaphrodite ('hermaphroditum') is unstable and the correlation
with other morphological characters uncertain. One approach that PAF may take is
that no subspecific taxa be recognized.
Empetrum nigrum L.
subsp. nigrum 2n=26 (2x) is a boreal entity in
northernorthern Europe and probably very rarely reaches the North Boreal, let
alone the Arctic. Arctic records should be checked very carefully. No convincing
material has been seen from Iceland and there are no diploid counts from there
by the Löves. Inorthern Norway subsp. nigrum stops far south
of the Arctic.
Empetrum nigrum L. subsp. hermaphroditum
(Hagerup) Böcher , Medd. Grønl. 149, 9: 81. 1952.
Basiynom E.
hermaphroditum Hagerup, Dansk Bot. Ark. 5, 2: 1.1927.
Synonom
Empetrum eamesii Fernald and Wiegand subsp. hermaphroditum
(Hagerup) D.Löve, Rhodora 62: 289. 1960.
2n = 52 (4x).
Löve and Löve (1975) listed numerous counts, several as arctic,
but many counts probably refer to other taxa in Tzvelev's proposal.
The
range of subsp. hermaphroditum should probably be dramatically reduced
from its usually indicated circumpolar range if subsp. subholarcticum is
recognised. Tzvelev in Tolmachev and Yurtsev (1980, Fl. Arct. USSR 8), mainly
based on the treatment of V.N.Vassilev, excluded it from the Russian Far East
and almost all of Siberia and the same is probably the case with Alaska and much
of Canada. Löve and Löve (1975) included E. androgynum
V.N.Vassil. in this entity (Elven). At this time we have retained the subspecies
status of this taxon to draw attention to the hermaphrodite flowers found in
plants of this taxon growing in the eastern Canadian Arctic Archipelago.
Illustrations. • Close-up of fruit. Mature blue Iqaluit blackberries. The leaves are cylindrical. The leaf margins almost meet and surround an internal air space. A leaf showing the underside is above the piece of fluf on the rock. Nunavut, Baffin Island, Iqaluit. Aiken 97–005.
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).
