# 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. 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. | Accepted | | | | | | | |
| 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
* ↑ GBIF Secretariat, ed. (2016). "Ledum L." GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ GBIF Secretariat, ed. (2016). "Ledum angustifolium Hort. ex Lavallée". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ TPL Reference: group=Ledum name=tro-50176889 Coming soon
* ↑ TPL Reference: group=Ledum name=tro-50092423 Coming soon
* 1 2 3 4 5 6 TPL Reference: group=Ledum name=tro-12300614 Coming soon
* ↑ GBIF Secretariat, ed. (2016). "Ledum columbianum Piper". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ TPL Reference: group=Ledum name=tro-12300613 Coming soon
* ↑ GBIF Secretariat, ed. (2016). "Ledum decumbens (Ait.) Loddiges". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ GBIF Secretariat, ed. (2016). "Ledum decumbens (Ait.) Loddiges ex Steudel". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ TPL Reference: group=Ledum name=kew-2349911 Coming soon
* 1 2 3 4 TPL Reference: group=Ledum name=kew-2355735 Coming soon
* ↑ GBIF Secretariat, ed. (2016). "Ledum decumbens Small". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ TPL Reference: group=Ledum name=tro-12300073 Coming soon
* ↑ GBIF Secretariat, ed. (2016). "Ledum glandulosum Nutt". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ TPL Reference: group=Ledum name=tro-12302631 Coming soon
* ↑ TPL Reference: group=Ledum name=tro-12300615 Coming soon
* ↑ TPL Reference: group=Ledum name=tro-12302504 Coming soon
* ↑ GBIF Secretariat, ed. (2016). "Ledum groenlandicum Oeder". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ TPL Reference: group=Ledum name=kew-2349909 Coming soon
* 1 2 TPL Reference: group=Ledum name=kew-2355734 Coming soon
* ↑ GBIF Secretariat, ed. (2016). "Ledum groenlandicum Retz". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ GBIF Secretariat, ed. (2016). "Ledum groenlandicum f. denudatum Vict. & J.Rousseau". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ GBIF Secretariat, ed. (2016). "Ledum groenlandicum var. aridiphilum D.Löve". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ TPL Reference: group=Ledum name=tro-50298977 Coming soon
* ↑ GBIF Secretariat, ed. (2016). "Ledum groenlandicum var. aridiphilum D.Löve". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ GBIF Secretariat, ed. (2016). "Ledum hypoleucum Komarov". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ TPL Reference: group=Ledum name=tro-12303119 Coming soon
* ↑ GBIF Secretariat, ed. (2016). "Ledum idahoensis". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ GBIF Secretariat, ed. (2016). "Ledum macrophyllum Tolm". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* 1 2 3 TPL Reference: group=Ledum name=tro-12300074 Coming soon
* ↑ GBIF Secretariat, ed. (2016). "Ledum maximum (Nakai) A.P.Khokhrjakov & M.T.Mazurenko". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* 1 2 TPL Reference: group=Ledum name=tro-50194624 Coming soon
* ↑ GBIF Secretariat, ed. (2016). "Ledum palustre L." GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* 1 2 3 TPL Reference: group=Ledum name=kew-2349893 Coming soon
* ↑ GBIF Secretariat, ed. (2016). "Ledum palustre Michx". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ TPL Reference: group=Ledum name=tro-50156076 Coming soon
* ↑ GBIF Secretariat, ed. (2016). "Ledum palustre subsp. angustissimum Worosch". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ TPL Reference: group=Ledum name=tro-12303120 Coming soon
* ↑ GBIF Secretariat, ed. (2016). "Ledum palustre subsp. groenlandicum (Oeder) Hulten". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ GBIF Secretariat, ed. (2016). "Ledum palustre var. angustifolium Hook". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ TPL Reference: group=Ledum name=tro-50156075 Coming soon
* ↑ TPL Reference: group=Ledum name=kew-2355732 Coming soon
* ↑ GBIF Secretariat, ed. (2016). "Ledum palustre var. diversipilosum Nakai". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ TPL Reference: group=Ledum name=tro-12303121 Coming soon
* ↑ GBIF Secretariat, ed. (2016). "Ledum palustre var. latifolium (Jacq.) Hook". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ GBIF Secretariat, ed. (2016). "Ledum palustre var. latifolium (Jacq.) Michx". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ TPL Reference: group=Ledum name=tro-50194625 Coming soon
* ↑ TPL Reference: group=Ledum name=tro-50156073 Coming soon
* ↑ TPL Reference: group=Ledum name=tro-50194628 Coming soon
* ↑ GBIF Secretariat, ed. (2016). "Ledum serpyllifolium". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ GBIF Secretariat, ed. (2016). "Ledum subulatum (Nakai) A.P.Khokhrjakov & M.T.Mazurenko". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ TPL Reference: group=Ledum name=tro-50194629 Coming soon
Rhododendron
* ↑ GBIF Secretariat, ed. (2016). "Rhododendron columbianum (Piper) Harmaja". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* 1 2 GBIF Secretariat, ed. (2016). "Rhododendron tomentosum subsp. decumbens (Aiton) Elven & D.F.Murray". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* 1 2 GBIF Secretariat, ed. (2016). "Rhododendron neoglandulosum Harmaja". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* 1 2 3 4 5 GBIF Secretariat, ed. (2016). "Rhododendron groenlandicum (Oeder) K.A. Kron & W.S. Judd". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* 1 2 3 GBIF Secretariat, ed. (2016). "Rhododendron diversipilosum (Nakai) H. Harmaja". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* ↑ TPL Reference: group=Rhody name=tro-50303827 Coming soon
* 1 2 GBIF Secretariat, ed. (2016). "Rhododendron tomentosum Harmaja". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* 1 2 GBIF Secretariat, ed. (2016). "Rhododendron subulatum (Nakai) Harmaja". GBIF Backbone Taxonomy. Retrieved 2017-09-20.
* 1 2 TPL Reference: group=Rhody name=tro-50223463 Coming soon
Other
* ↑ TPL Reference: group=Kalmia name=tro-50310693 Coming soon

### 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.