Bog Rosemary

Appearance

It is a small shrub growing to 10–20 cm tall with slender stems. The leaves are evergreen, alternately arranged, lanceolate, 1–5 cm long and 2–8 mm broad, dark green above and white beneath with the leaf margins curled under. The flowers are bell-shaped, white to pink, 5–8 mm long; flowering is in late spring to early summer. The fruit is a small capsule containing numerous seeds.

Naming

The genus was named by Carl Linnaeus who observed it during his 1732 expedition to Lapland and compared the plant to Andromeda from Greek mythology. The specific epithet is a noun in apposition, which Linnaeus based on Johann Christian Buxbaum's pre-Linnaean generic designation ''Polifolia''. Buxbaum in turn derived the name from Johann Bauhin, who used it to mean "having ''polium''-like leaves". The precise plant that Bauhin meant by ''polium'' is uncertain, but it may have been ''Teucrium montanum''. The common name "bog rosemary" derives from the superficial resemblance of the leaves to those of rosemary, which is not closely related.

Andromeda polifolia L. var. jamesiana (Lepage) Boivin
Andromeda polifolia L. var. glaucophylla (Link) DC
Andromeda polifolia L. var. polifolia

There are two varieties, treated as distinct species by some botanists:
''Andromeda polifolia'' var. ''polifolia''. Northern Europe and Asia, northwestern North America.
''Andromeda polifolia'' var. ''latifolia'' Aiton [1789]. Northeastern North America.

Distribution

Bog rosemary is circumboreal and circumpolar. In North America bog rosemary is transcontinental, occurring from Greenland westward through all of the Canadian provinces to Alaska and south to Washington and Idaho and Nevada. It occurs south along the north Atlantic coast to New Jersey and west to Illinois and Minnesota.

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Habitat

In north America bog rosemary typically occurs in boreal and polar sphagnum (Sphagnum spp.) - and sedge (Carex spp. and Eriophorum spp.) - dominated bog, swamp, peatland, and fen communities. These communities often have a scattered component of scrubby conifers, most commonly black spruce (Picea mariana) and tamarack (Larix laricina), and ericaceous (Ericaceae) shrubs such as leatherleaf (Chamaedaphne calyculata), Labrador tea (Ledum spp.), and bog laurel (Kalmia polifolia).

Reproduction

Bog rosemary primarily regenerates vegetatively by rhizomes. A. polifolia var. polifolia also has stems that root along the nodes. Bog rosemary can reproduce from seeds, but seedling establishment in nature is apparently rare, and vegetative reproduction is presumably more important than that by seeds.

Pollination: Bog rosemary can be self pollinated and is considered highly self fertile. Self pollination readily takes place in bog rosemary when the flowers are newly expanded because the stigma is situated quite close to the anthers, and pollen grains are trapped by hairs lining the corolla. Flowers are also pollinated by bumblebees, honeybees, syrphid flies, and butterflies. Some research suggests that insect pollination is very important, or even required, for seed production in bog rosemary. In a Swedish pollination study, Froborg reported that self-pollinated flowers did not differ from open-pollinated flowers in the percent of flowers producing fruit, but the percent of seed set per ovule was significantly lower (P<0.001) with self pollination. In a pollination study of A. polifolia var. glaucophylla in Ontario, Reader found that the number of seed bearing fruits was reduced significantly (P<0.01) when insects were prevented from visiting flowers by mesh bags. The number of fruits producing seeds ranged from 0 to 1.5 on bagged plants, and 26.1 to 40.8 for nonbagged plants.

Breeding system: Bog rosemary is monoecious.

Seed production: Bog rosemary produces 1 to 44 seeds per fruit, of which 10 to 20 are usually viable.

Seed dispersal: Campbell and others suggest that the potential for wind dispersal of bog rosemary seeds is low because the seeds are enclosed in fleshy fruits. However, Jacquemart writes "the small seeds of bog rosemary are presumably wind dispersed". Perhaps she is speaking to seed dispersal after the fruit has worn away. The fruits have a potential for animal dispersal; however, it is unlikely that the bitter fruits would be eaten in quantity. The fruits of A. polifolia var. glaucophylla have been found to float for 72 hours, indicating a potential for water dispersal of seed.

Seed banking: In a seed banking study of a bog in Finland, viable seeds of bog rosemary were found in the soil surface layer and at a depth of 15.7 to 19.7 inches (40-50 cm). According to Jacquemart, bog rosemary is often "under-represented" in the seed banks of sphagnum bogs in the British Isles.

Germination: Bog rosemary seeds require cold stratification to germinate . The seeds must stay in the soil for at least 1 year before they can germinate. The best available information on seed germination comes from a Belgian greenhouse study. The average germination time was 13 days. Seeds collected in October germinated at a rate of 66.5% at 77 F (25 C) and 16 hours of light. Germination rate was only 24% to 27% in shade or darkness. The study found that cold temperatures reduced bog rosemary seed germination. Germination rates reached 72% at 86 F (30 C), but dropped to 27% at 59 F (15 C). Germination period was 8 days at 86 F (30 C) and 34 days at 59 F (15 C). Chilling treatments in which the seeds were immersed in moist sand at 39.2 F (4 C) did not increase the germination rate, but germination was faster (11 versus 13 days). Two months of dry storage at -4 F (-20 C) was damaging to seeds and resulted in a 4% germination rate. In the first few years following a fire, spring and summer soil temperatures may increase due to the removal of surface litter and overstory vegetation that once shaded the soil surface. According to the results of the germination study, these warmer soil temperatures may favor the germination of banked bog rosemary seeds.

Seedling establishment/growth: Seedling development in bog rosemary is relatively slow. In greenhouse studies, 11 days are required after radicle emergence before the first 2 cotyledons appear. The first 2 foliage leaves appear 18 to 28 days after radicle emergence. After 6 weeks the seedling consists of a slender vertical shoot, 0.4 to 0.8 inch (1-2 cm) long.

Froborg states that seedling establishment of bog rosemary and other clonal plants is "infrequent, but important, in disturbed areas". When dispersal and new establishment of bog rosemary occurs, it is presumably by seed.

On a milled peatland in Quebec, 6 to 20 years after harvesting, bog rosemary had failed to recolonize the disturbed area although it was present in the adjacent undisturbed peatlands. This may have been the result of establishment failure or failure to disperse. Additional information on seedling establishment is lacking, and more studies are needed.

Vegetative regeneration: Bog rosemary sprouts readily from rhizomes that produce roots and aboveground shoots. Shoots develop from the terminal ends of the rhizomes. The creeping stems of A. polifolia var. polifolia commonly root along the nodes, but there is no discussion in the literature regarding stem rooting as a mode of regeneration following disturbance.

Uses

Bog rosemary contains a poisonous glucoside called andromedotoxin. Domestic browsing animals usually reject bog rosemary, but the plant has killed domestic sheep.

The heather vole feeds on leaves and fruits of bog rosemary. Bog rosemary was found in rumen samples of barren-ground caribou in northern Canada, but only in minute amounts. The caribou eat bog rosemary in November and January, when the animals frequent the muskegs. Moose on the Kenai Peninsula, Alaska may occasionally feed on bog rosemary in all months of the year on heavily used range, and in Lapland, capercaille will feed on the bog rosemary leaves. The andromedotoxin found in all parts of bog rosemary plants is poisonous to humans, causing low blood pressure, breathing problems, dizziness, vomiting, and diarrhea.

Cultivar 'Compacta' is a small evergreen shrub to 20cm in height, with oval leaves and terminal clusters of clear pink, globose flowers and is grown as an ornamental. Other cultivated varieties of bog rosemary have been developed, including 'Blue Ice', 'Grandiflora Compacta', and 'Nana'.

Bog rosemary is planted as an ornamental, although it is reportedly hard to grow. It may be collected as seed, stem cuttings, or plant divisions. Seeds should be sown in February or March, and should be cold-stratified at 53.6 F (12 C) for 1 to 2 months before planting. Seedlings should be grown for at least 2 years before outplanting, and they should be overwintered in a greenhouse. Seedlings can be planted in early summer once they reach 6 inches (15 cm) in height. Cuttings of bog rosemary should be collected in November and December. Cuttings planted in summer take root in about 15 months. Plant divisions should be collected in the early spring. The plants should be "dropped" beforehand, which entails digging up the plant 6 to 12 months earlier and replanting it somewhat more deeply. The buried branches then root and form new plants when divided.

Cultural

Used by the Tanana of Alaska as a beverage.