Rhododendron subsect. Ledum

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.Template:Sfn 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 species	Author	GBIF status	TPL status	GBIF Accepted species	Author	GBIF status	TPL Accepted species	Author	TPL status
Ledum	L.	Accepted
Ledum angustifolium	Hort. ex Lavallée	Accepted
Ledum buxifolium	Bergius		Synonym				Kalmia buxifolia	(Bergius) Gift & Kron	Accepted
Ledum californicum	Kellogg		Synonym				Ledum glandulosum		Accepted
Ledum 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		Accepted
Ledum decumbens	Small	Accepted	Accepted
Ledum glandulosum	Nutt.	Synonym	Accepted	Rhododendron neoglandulosum	Harmaja	Accepted
Ledum glandulosum subsp. glandulosum			Synonym				Ledum glandulosum		Accepted
Ledum glandulosum var. californicum	(Kellogg) C.L.Hitchc.		Synonym				Ledum glandulosum		Accepted
Ledum glandulosum var. glandulosum			Synonym				Ledum glandulosum		Accepted
Ledum groenlandicum	Oeder	Synonym	Synonym	Rhododendron groenlandicum	(Oeder) K.A.Kron & W.S.Judd	Accepted	Ledum palustre subsp. groenlandicum		Accepted
Ledum 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		Accepted
Ledum groenlandicum var. aridiphilum	D.Löve	Accepted
Ledum hypoleucum	Kom.	Synonym	Synonym	Rhododendron diversipilosum	(Nakai) H.Harmaja	Accepted	Rhododendron hypoleucum	(Kom.) Harmaja	Accepted
Ledum 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		Accepted
Ledum 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		Accepted
Ledum palustre subsp. groenlandicum	(Oeder) Hultén	Synonym	Accepted	Rhododendron groenlandicum	(Oeder) K.A.Kron & W.S.Judd	Accepted
Ledum palustre var. angustifolium	Hook.	AcceptedTemplate:Efn
Ledum palustre var. angustum	E.A.Busch		Synonym				Ledum palustre		Accepted
Ledum palustre var. decumbens	Aiton		Synonym				Ledum palustre subsp. decumbens		Accepted
Ledum palustre var. diversipilosum	Nakai	Synonym	Synonym	Rhododendron diversipilosum	(Nakai) H.Harmaja	Accepted	Ledum macrophyllum		Accepted
Ledum 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		Accepted
Ledum palustre var. palustre			Synonym				Ledum palustre		Accepted
Ledum palustre var. subulatum	Nakai		Synonym				Rhododendron subulatum	(Nakai) Harmaja	Accepted
Ledum 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

File:LedumEssOil.png

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.

See also

• List of sections in subgenus Rhododendron