Ledum was a genus in the family Ericaceae, including eight species of evergreen shrub native to cool temperate and subarctic regions of the Northern Hemisphere and commonly known as Labrador tea. It is now recognised as a subsection of section Rhododendron, subgenus Rhododendron, of the genus Rhododendron.
Description Ledum species often grow 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.
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 listed in genus Ledum (accepted and synonyms), with their current accepted names are: Ledum speciesAuthorGBIF statusTPL statusGBIF Accepted speciesAuthorGBIF statusTPL Accepted speciesAuthorTPL statusLedum L. Accepted Ledum angustifolium Hort. ex Lavallée Accepted Ledum buxifolium Bergius Synonym Kalmia buxifolia (Bergius) Gift & Kron AcceptedLedum californicum Kellogg Synonym Ledum glandulosum AcceptedLedum columbianum Piper Synonym Accepted Rhododendron columbianum (Piper) Harmaja Accepted Ledum decumbens (Ait.) Lodd. Synonym Rhododendron tomentosum subsp. decumbens (Aiton) Elven & D.F.Murray Accepted Ledum decumbens (Ait.) Lodd. ex Steud. Synonym Synonym Rhododendron tomentosum subsp. decumbens (Aiton) Elven & D.F.Murray Accepted Ledum palustre subsp. decumbens AcceptedLedum decumbens Small Accepted Accepted Ledum glandulosum Nutt. Synonym Accepted Rhododendron neoglandulosum Harmaja Accepted Ledum glandulosum subsp. glandulosum Synonym Ledum glandulosum AcceptedLedum glandulosum var. californicum (Kellogg) C.L.Hitchc. Synonym Ledum glandulosum AcceptedLedum glandulosum var. glandulosum Synonym Ledum glandulosum AcceptedLedum groenlandicum Oeder Synonym Synonym Rhododendron groenlandicum (Oeder) K.A.Kron & W.S.Judd Accepted Ledum palustre subsp. groenlandicum AcceptedLedum groenlandicum Retz. Accepted Ledum groenlandicum f. denudatum Vict. & J.Rousseau Accepted Ledum groenlandicum subsp. glandulosum (Nutt.) Á.Löve & D.Löve Synonym Synonym Rhododendron neoglandulosum Harmaja Accepted Ledum glandulosum AcceptedLedum groenlandicum var. aridiphilum D.Löve Accepted Ledum hypoleucum Kom. Synonym Synonym Rhododendron diversipilosum (Nakai) H.Harmaja Accepted Rhododendron hypoleucum (Kom.) Harmaja AcceptedLedum idahoensis Accepted Ledum macrophyllum Tolm. Synonym Accepted Rhododendron diversipilosum (Nakai) H.Harmaja Accepted Ledum maximum (Nakai) A.P.Khokhr. & M.T.Mazurenko Synonym Accepted Rhododendron tomentosum Harmaja Accepted Ledum palustre L. Synonym Accepted Rhododendron tomentosum Harmaja Accepted Ledum palustre Michx. Synonym Rhododendron groenlandicum (Oeder) K.A.Kron & W.S.Judd Accepted Ledum palustre f. decumbens (Aiton) Y.L.Chou & S.L.Tung Synonym Ledum palustre subsp. decumbens AcceptedLedum palustre subsp. angustissimum Worosch. Synonym Rhododendron subulatum (Nakai) Harmaja Accepted Ledum palustre subsp. decumbens (Aiton) Hultén Accepted Ledum palustre subsp. diversipilosum Hara Synonym Ledum macrophyllum AcceptedLedum palustre subsp. groenlandicum (Oeder) Hultén Synonym Accepted Rhododendron groenlandicum (Oeder) K.A.Kron & W.S.Judd Accepted Ledum palustre var. angustifolium Hook. Accepted Ledum palustre var. angustum E.A.Busch Synonym Ledum palustre AcceptedLedum palustre var. decumbens Aiton Synonym Ledum palustre subsp. decumbens AcceptedLedum palustre var. diversipilosum Nakai Synonym Synonym Rhododendron diversipilosum (Nakai) H.Harmaja Accepted Ledum macrophyllum AcceptedLedum palustre var. latifolium (Jacq.) Hook. Synonym Rhododendron groenlandicum (Oeder) K.A.Kron & W.S.Judd Accepted Ledum palustre var. latifolium (Jacq.) Michx. Synonym Rhododendron groenlandicum (Oeder) K.A.Kron & W.S.Judd Accepted Ledum palustre var. maximum Nakai Synonym Ledum maximum AcceptedLedum palustre var. palustre Synonym Ledum palustre AcceptedLedum palustre var. subulatum Nakai Synonym Rhododendron subulatum (Nakai) Harmaja AcceptedLedum serpyllifolium Accepted Ledum subulatum (Nakai) A.P.Khokhr. & M.T.Mazurenko Synonym Synonym Rhododendron subulatum (Nakai) Harmaja Accepted Rhododendron subulatum (Nakai) Harmaja Accepted
Species references Ledum
Rhododendron
Other
Hybrids Natural hybrids (nothospecies) also occur. Ledum columbianum = Rhododendron × columbianum (R. groenlandicum × R. neoglandulosum) is listed by Harri Harmaja as a natural hybrid. Rhododendron vanhoeffeni Abromeit is a probably hybrid between Ledum palustre subsp. decumbens and Rhododendron lapponicum.
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.
See also List of sections in subgenus Rhododendron
Notes
References
Bibliography