Ledum

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Rhododendron subsect. Ledum
Rhododendron neoglandulosum (Ledum glandulosum)
Scientific classification
Kingdom:Plantae
(unranked):Angiosperms
(unranked):Eudicots
(unranked):Asterids
Order:Ericales
Family:Ericaceae
Genus:Rhododendron
Species

See text.

 
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Rhododendron subsect. Ledum
Rhododendron neoglandulosum (Ledum glandulosum)
Scientific classification
Kingdom:Plantae
(unranked):Angiosperms
(unranked):Eudicots
(unranked):Asterids
Order:Ericales
Family:Ericaceae
Genus:Rhododendron
Species

See text.

Ledum is a genus name formerly widely recognised in the family Ericaceae, including 8 species of evergreen shrubs native to cool temperate and subarctic regions of the Northern Hemisphere and commonly known as Labrador Tea.

Contents

Taxonomy

Reclassification into Rhododendron

Recent genetic evidence has shown that the species previously treated in this genus are correctly placed in the genus Rhododendron, where they are now treated as Rhododendron subsect. Ledum.

Because some of the species names used in Ledum could not be used in Rhododendron (the names already having been used for other species already in this large genus), new names had to be coined for them.

Species

The species formerly listed in Ledum, with their current accepted names in Rhododendron, are:

Hybrids

One natural hybrid also occurs:

Uses

Ledum (L. groenlandicum) essential oil in clear glass vial

Some species (e.g. L. groenlandicum) have been used to produce Labrador Tea. Other species have varying levels of toxicity (e.g. L. glandulosum). Evergreen Labrador Tea grows slowly, but retains its leaves year-round. Users should take care not to over-harvest leaves from any single plant.

Ledum sp. often grows together with poisonous plants such as Bog-laurel and Bog-rosemary, but certain species (e.g. L. groenlandicum and L. palustre) are easily distinguished by the distinctive rust coloured fuzz on the bottom of leaves.

According to a Russian study from 1991[citation needed], Ledum was able to almost completely inactivate the tick-borne bacterial infection caused by Borrelia, involved in the pathogenesis of Lyme Disease.

References

1. Kron, Kathleen A. & Judd, Walter S. (1990) Phylogenetic Relationships within the Rhodoreae (Ericaceae) with Specific Comments on the Placement of Ledum Systematic Botany (1990), 1S(1): pp. S7-68

2. Harmaja, Harri (1990) New names and nomenclatural combinations in Rhododendron (Ericaceae) Ann. Bot. Fennici 27:203-204

3. Harmaja, Harri (1991) Taxonomic notes on Rhododendron subsection Ledum (Ledum, Ericaceae), with a key to its species. Ann. Bot. Fennici 28: 171-173.

4. Harmaja, Harri (1999) Rhododendron diversipilosum, comb. nov. (Ericaceae). Ann. Bot. Fennici 35: 263-264

5. Harmaja, Harri (2002) Rhododendron subulatum, comb. nova (Ericaceae). Ann. Bot. Fennici 39: 183-184

6. Kihlman, Bengt A. (2004) Hybrids Between Ledums and Lepidote Rhododendrons. Journal of the American Rhododendron Society 58(2):74-81

7. Fokina, GI. Vopr Virusol, (1991) Experimental phytotherapy of tick-borne encephalitis,