Ledum

Uses
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, Ledum was able to almost completely inactivate the Tick-Borne indolent bacterial infection caused by the Genus Borrelia, some people believe to be involved in the pathogenesis of Lyme Disease which can lead to many chronic conditions.

Species
The species formerly listed in Ledum, with their current accepted names in Rhododendron, are:
Ledum decumbens = Rhododendron subarcticum Harmaja
Ledum glandulosum = Rhododendron neoglandulosum Harmaja
Ledum groenlandicum = Rhododendron groenlandicum (Oeder) Kron & Judd
Ledum hypoleucum = Rhododendron hypoleucum (Kom.) Harmaja
Ledum macrophyllum = Rhododendron tolmachevii Harmaja
Ledum palustre = Rhododendron tomentosum Harmaja
Ledum palustre var. diversipilosum = Rhododendron diversipilosum (Nakai) Harmaja
Ledum subulatum = Rhododendron subulatum (Nakai) Harmaja

Hybrids
One natural hybrid also occurs:
Ledum columbianum = Rhododendron × columbianum (R. groenlandicum × R. neoglandulosum)

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.

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.