Rhododendron lapponicum (L.) Wahlenb.
Lapland Rosebay.
Ericaceae, bilberry family.
Fl. Lapp. 104. 1812.
Azalea lapponica L. Sp. Pl. 151. 1753.
Rhododendron parvifolium Adams, Nouv. Mém. Soc. Naturalistes
Moscou 3, 9: 237. 1834.
Rhododendron lapponicum L. var.
parvifolium (Adams) Herder
Rhododendron lapponicum (L.)
Wahlenb. subsp. alpinum (Glehn) Khokhr. Sosud. Rast. Sovet. Dal'nego
Vostoka 5: 133. 1991.
Vegetative morphology. Plants shrubs; dwarf shrubs, or low shrubs; 5–10 cm high (to 80 cm tall in protected sites where plants grow erect); semi-prostrate, rarely erect, matted from much branching, scruffy twigs and bearing conspicuous purple-pink flowers. Aerial stems erect (in sheltered sites), or prostrate; glabrous. Leaves distributed along the stems; alternate; evergreen. Stipules absent. Petioles present; 0.5–1.5 mm long; with sessile glands; glabrous. Leaf blade bases acute. Blades 4–12 mm long; 3–6 mm wide. Blades spreading; leathery; elliptic, or oblanceolate; flat; appearing single-veined. Blades adaxial surface with sessile glands; glabrous. Blades abaxial surface with sessile glands (that are very dense and appear as pock marks); glabrous. Blade margins entire; glabrous. Leaf apices acuminate, or acute.
Reproductive morphology. Flowering stems absent. Inflorescence fasciculate (with a few flowers); axillary. Pedicels present. Pedicels bract leaves 5–10 mm long. Flowers per inflorescence (1–)3(–5); medium-sized, 5–15 mm in diameter or length. Calyx sepals 5; fused (at the base); 0.5–1 mm long (tiny). Calyx brown; rotate; 5-lobed; with sessile glands; glabrous. Petals fused; 5; purple (fading pale purple or pinkish; very fragrant); 7–12 mm long. Corolla rotate; 5-lobed. Stamens 10. Anthers yellow; 0.8–1.4 mm long (opening by 1–2 terminal pores). Nectaries present. Gynoecia superior. Carpels syncarpous; 5. Ovaries ovate; with sessile glands. Styles 1. Placentation axile. Ovules numerous. Fruit stalked; stalk 8–10 mm long. Fruit with calyx persisting; dry; a capsule; conical; not distinctly flattened; dehiscent; opening with teeth at the top of the capsule; teeth 5. Fruit 4.5–5.5 mm long; 3.5–4.5 mm wide; yellowish; glabrous (covered with sessile glands); surface appearing veinless. Seeds 1–1.2 mm long (ellipsoid); yellowish; with surfaces smooth.
Chromosome information. 2n = 26 and 52. Hagerup (1928);
Janaki-Ammal et al. (1950); Jørgensen et al. (1958 Greenland); Löve
and Löve (1966b north eastern USA, 1982a arctic Canada); Zhukova (1967
north eastern Asia, as R. parvifolium); Murin et al. (1984 central Asia,
as R. parvifolium).
52 (4x). - Janaki-Ammal et al. (1950).
Ploidy levels recorded 2x&4x.
Distribution. Northern hemisphere distribution: North American; Greenland, Canada, United States, Eurasia. Yukon, Northwest Territories Islands, Continental Northwest Territories, Nunavut Islands, Continental Nunavut, Northern Québec. Low arctic, or alpine. Range in the Canadian Arctic Archipelago widespread (on islands south of the Parry Channel, e.g. Southamptons, Salisbury, and Boothia Peninsula). Arctic Islands: Baffin, Devon, Banks, Victoria, Southampton.
Ecology and habitat. Substrates: tundra, slopes, ridges, dry meadows; dry; non-littoral; rocks, gravel; with low organic content.
Notes. There is a second taxon that has been recognized and that is
R. parviflorum. The main difference between the taxa is the number of
stamens: 5 in typical R. lapponicum, 10 in typical R. parvifolium,
and (5) 8 (10) in many East Siberian - Far East populations (Khokhryakov and
Mazurenko 1991), mostly 7–8 in the plants of Alaska and Yukon
(Hultén 1968). Vinogradova in Vinogradova and Yurtsev (1980) confirmed
constant occurrence of 10 stamens in the Asian population.
Statistical-geographic studies over the whole range of the R. lapponicum
(L.) Wahlenb. aggregate are needed to determine the status of both taxa
(subspecies? gene geography?) At the present stage of knowledge of R.
lapponicum s.l., the taxon R. parvifolium is included in R.
lapponicum s.l., pending further study (Elven personal communication 2001).
Kron and Judd (1990) [Syst. Bot. 15: 57–68.] analyzed the relationships
among the genera close to Rhododendron and argued strongly for inclusion
of Ledum in Rhododendron, even at as low level as a subsection of
one of the eight subgenera. As yet, this has not been widely taken up.
Illustrations. • Plant habitat. Short plants towards the northern limit of their distribution. Nunavut, Baffin Island. Aiken 02–003. CAN. • Plant habitat. Shrubby plants beside the markers, growing prostrate away from the rock and erect on the surface of the rock. Manitoba, Churchill, July 22, 2001. Aiken and Brysting 01–006. CAN. • Stunted plant.. Stunted plant towards the northern limit of the species distribution. Nunavut, Baffin Island, Soper River Valley near Mt. Joy. Aiken, 7 July, 2002. No voucher. • Inflorescence in bud.. Inflorescenc with 3 possibly 4 young buds with grey and rusty brown sepals, and purple petals. Aiken 02–003. Nunavut, Baffin Island, Iqaluit. • Inflorescence with opening buds. Inflorescence with three buds. One sepal that is in the process of being shed is still present. Nunavut, Baffin Island, Iqaluit. Aiken 02–003. • Close-up of fruiting plant. Shrubby plants beside the markers, growing prostrate away from the rock and erect on the surface of the rock. Manitoba, Churchill, July 22, 2001. Aiken and Brysting 01–006. CAN. • Close-up of leaves. Close-up of mature leaves that are covered with glandular dots. Note pale yellow green new leaves that are surrounded by stipules. Nunavut, Baffin Island. Iqaluit. 02–003. CAN. • Surface view of growing apex.. Leaf with conspicuous white sessile glands. Note stipules at the base of leaf buds that ore out of focus. AIken July, 2002. Nunavut, Baffn Island. • Flowering plant habit. Conspicuous purplish-pink flowers (5-)10–15 mm in diameter borne in groups of 2–4. Plants growing in a dense low Arctic tundra with Dryas, willow, Carex and Bilberry. Nunavut, Baffin Island, on rocky hillside north of Iqaluit. 19 July 1982, J.M. Gillett 18959. CAN. • Close-up of flowers. Flowers 10–15 mm across, with bright pink petals, pale pink filaments topped by dark red anthers shedding yellow pollen from apical pores, and dark pink-red styles with small yellow capitate stigmas. Brown fruit capsules from the previous season have dehisced. Nunavut, Baffin Island, Iqaluit, growing on rocky hillside, north of the town, 19 July 1982, J.M. Gillett 18959. CAN. • Close-up of fruit. Fruit capsules with persistent, long, slender styles. On the right hand fruit, the remains of the petals are still attached. The stippled appearance of the leaf surfaces results from sessile glands. Manitioba, Churchill, 22 July, 2001. Aiken and Brysting 01–006. CAN. • Close-up of fruit. Capsules that have split into the five segments of the original carpels (light brown) and show the (dark brown) central axis of the axile placentation, characteristic of the family. The seeds have been dispersed. The upper leaf surfaces have numerous sessile and whitish glands. Aiken and Brysting 01–006. • Herbarium specimen. Note undersides of leaves that are rusty reddish, from the abundant, sessile glands present. Flowers deepened to darker purple when dried. Nunavut, Baffin Island, Burwash Bay, South coast; Nettilling Lake. 15 July 1986. J.D. Jacobs and L. Maus s.n. CAN 517677. • 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).
