Rhododendron subsect. Ledum

Rhododendron subsect. Ledum
	Rhododendron columbianum (Ledum glandulosum)
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Asterids
Order:	Ericales
Family:	Ericaceae
Genus:	Rhododendron
Subgenus:	Rhododendron subg. Rhododendron
Section:	Rhododendron sect. Rhododendron
Subsection:	R. subsect. Ledum; (L.) Kron & Judd
Species
	See text

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.^[1] 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.^[2]

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 1]}
Ledum angustifolium	Hort. ex Lavallée	Accepted^{[Ledum 2]}
Ledum buxifolium	Bergius		Synonym^{[Ledum 3]}				Kalmia buxifolia	(Bergius) Gift & Kron	Accepted^{[Kalmia 1]}
Ledum californicum	Kellogg		Synonym^{[Ledum 4]}				Ledum glandulosum		Accepted^{[Ledum 5]}
Ledum columbianum	Piper	Synonym^{[Ledum 6]}	Accepted^{[Ledum 7]}	Rhododendron columbianum	(Piper) Harmaja	Accepted^{[Rhody 1]}
Ledum decumbens	(Ait.) Lodd.	Synonym^{[Ledum 8]}		Rhododendron tomentosum subsp. decumbens	(Aiton) Elven & D.F.Murray	Accepted^{[Rhody 2]}
Ledum decumbens	(Ait.) Lodd. ex Steud.	Synonym^{[Ledum 9]}	Synonym^{[Ledum 10]}	Rhododendron tomentosum subsp. decumbens	(Aiton) Elven & D.F.Murray	Accepted^{[Rhody 2]}	Ledum palustre subsp. decumbens		Accepted^{[Ledum 11]}
Ledum decumbens	Small	Accepted^{[Ledum 12]}	Accepted^{[Ledum 13]}
Ledum glandulosum	Nutt.	Synonym^{[Ledum 14]}	Accepted^{[Ledum 5]}	Rhododendron neoglandulosum	Harmaja	Accepted^{[Rhody 3]}
Ledum glandulosum subsp. glandulosum			Synonym^{[Ledum 15]}				Ledum glandulosum		Accepted^{[Ledum 5]}
Ledum glandulosum var. californicum	(Kellogg) C.L.Hitchc.		Synonym^{[Ledum 16]}				Ledum glandulosum		Accepted^{[Ledum 5]}
Ledum glandulosum var. glandulosum			Synonym^{[Ledum 17]}				Ledum glandulosum		Accepted^{[Ledum 5]}
Ledum groenlandicum	Oeder	Synonym^{[Ledum 18]}	Synonym^{[Ledum 19]}	Rhododendron groenlandicum	(Oeder) K.A.Kron & W.S.Judd	Accepted^{[Rhody 4]}	Ledum palustre subsp. groenlandicum		Accepted^{[Ledum 20]}
Ledum groenlandicum	Retz.	Accepted^{[Ledum 21]}
Ledum groenlandicum f. denudatum	Vict. & J.Rousseau	Accepted^{[Ledum 22]}
Ledum groenlandicum subsp. glandulosum	(Nutt.) Á.Löve & D.Löve	Synonym^{[Ledum 23]}	Synonym^{[Ledum 24]}	Rhododendron neoglandulosum	Harmaja	Accepted^{[Rhody 3]}	Ledum glandulosum		Accepted^{[Ledum 5]}
Ledum groenlandicum var. aridiphilum	D.Löve	Accepted^{[Ledum 25]}
Ledum hypoleucum	Kom.	Synonym^{[Ledum 26]}	Synonym^{[Ledum 27]}	Rhododendron diversipilosum	(Nakai) H.Harmaja	Accepted^{[Rhody 5]}	Rhododendron hypoleucum	(Kom.) Harmaja	Accepted^{[Rhody 6]}
Ledum idahoensis		Accepted^{[Ledum 28]}
Ledum macrophyllum	Tolm.	Synonym^{[Ledum 29]}	Accepted^{[Ledum 30]}	Rhododendron diversipilosum	(Nakai) H.Harmaja	Accepted^{[Rhody 5]}
Ledum maximum	(Nakai) A.P.Khokhr. & M.T.Mazurenko	Synonym^{[Ledum 31]}	Accepted^{[Ledum 32]}	Rhododendron tomentosum	Harmaja	Accepted^{[Rhody 7]}
Ledum palustre	L.	Synonym^{[Ledum 33]}	Accepted^{[Ledum 34]}	Rhododendron tomentosum	Harmaja	Accepted^{[Rhody 7]}
Ledum palustre	Michx.	Synonym^{[Ledum 35]}		Rhododendron groenlandicum	(Oeder) K.A.Kron & W.S.Judd	Accepted^{[Rhody 4]}
Ledum palustre f. decumbens	(Aiton) Y.L.Chou & S.L.Tung		Synonym^{[Ledum 36]}				Ledum palustre subsp. decumbens		Accepted^{[Ledum 11]}
Ledum palustre subsp. angustissimum	Worosch.	Synonym^{[Ledum 37]}		Rhododendron subulatum	(Nakai) Harmaja	Accepted^{[Rhody 8]}
Ledum palustre subsp. decumbens	(Aiton) Hultén		Accepted^{[Ledum 11]}
Ledum palustre subsp. diversipilosum	Hara		Synonym^{[Ledum 38]}				Ledum macrophyllum		Accepted^{[Ledum 30]}
Ledum palustre subsp. groenlandicum	(Oeder) Hultén	Synonym^{[Ledum 39]}	Accepted^{[Ledum 20]}	Rhododendron groenlandicum	(Oeder) K.A.Kron & W.S.Judd	Accepted^{[Rhody 4]}
Ledum palustre var. angustifolium	Hook.	Accepted^{[Ledum 40]}^[a]
Ledum palustre var. angustum	E.A.Busch		Synonym^{[Ledum 41]}				Ledum palustre		Accepted^{[Ledum 34]}
Ledum palustre var. decumbens	Aiton		Synonym^{[Ledum 42]}				Ledum palustre subsp. decumbens		Accepted^{[Ledum 11]}
Ledum palustre var. diversipilosum	Nakai	Synonym^{[Ledum 43]}	Synonym^{[Ledum 44]}	Rhododendron diversipilosum	(Nakai) H.Harmaja	Accepted^{[Rhody 5]}	Ledum macrophyllum		Accepted^{[Ledum 30]}
Ledum palustre var. latifolium	(Jacq.) Hook.	Synonym^{[Ledum 45]}		Rhododendron groenlandicum	(Oeder) K.A.Kron & W.S.Judd	Accepted^{[Rhody 4]}
Ledum palustre var. latifolium	(Jacq.) Michx.	Synonym^{[Ledum 46]}		Rhododendron groenlandicum	(Oeder) K.A.Kron & W.S.Judd	Accepted^{[Rhody 4]}
Ledum palustre var. maximum	Nakai		Synonym^{[Ledum 47]}				Ledum maximum		Accepted^{[Ledum 32]}
Ledum palustre var. palustre			Synonym^{[Ledum 48]}				Ledum palustre		Accepted^{[Ledum 34]}
Ledum palustre var. subulatum	Nakai		Synonym^{[Ledum 49]}				Rhododendron subulatum	(Nakai) Harmaja	Accepted^{[Rhody 9]}
Ledum serpyllifolium		Accepted^{[Ledum 50]}
Ledum subulatum	(Nakai) A.P.Khokhr. & M.T.Mazurenko	Synonym^{[Ledum 51]}	Synonym^{[Ledum 52]}	Rhododendron subulatum	(Nakai) Harmaja	Accepted^{[Rhody 8]}	Rhododendron subulatum	(Nakai) Harmaja	Accepted^{[Rhody 9]}

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.^[2]
Rhododendron vanhoeffeni Abromeit^[3] is a probably hybrid between Ledum palustre subsp. decumbens and Rhododendron lapponicum.^[2]

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.

Notes

References

Bibliography

Judd, Walter S. & Kron, Kathleen A. (2009). "Rhododendron Linnaeus, Sp. Pl. 1: 392. 1753; Gen. Pl. ed. 5, 185. 1754". Flora of North America. Vol. 8.
Kron, Kathleen A. & Judd, Walter S. (1990). "Phylogenetic Relationships within the Rhodoreae (Ericaceae) with Specific Comments on the Placement of Ledum". Systematic Botany. 15 (1): 57–68. doi:10.2307/2419016. ISSN 0363-6445. JSTOR 2419016.
Harmaja, Harri (1990). "New names and nomenclatural combinations in Rhododendron (Ericaceae)". Ann. Bot. Fennici. 27 (2): 203–204. JSTOR 23725435.
Harmaja, Harri (1991). "Taxonomic notes on Rhododendron subsection Ledum (Ledum, Ericaceae), with a key to its species". Ann. Bot. Fennici. 28 (2): 171–173. JSTOR 23725406.
Harmaja, Harri (1999). "Rhododendron diversipilosum, comb. nov. (Ericaceae)" (PDF). Ann. Bot. Fennici. 35: 263–264.
Harmaja, Harri (2002). "Rhododendron subulatum, comb. nova (Ericaceae)" (PDF). Ann. Bot. Fennici. 39: 183–184.
Kihlman, Bengt A. (2004). "Hybrids Between Ledums and Lepidote Rhododendrons". Journal of the American Rhododendron Society. 58 (2): 74–81.

[1]

[2]

[Ledum 1]

[Ledum 2]

[Ledum 3]

[Kalmia 1]

[Ledum 4]

[Ledum 5]

[Ledum 6]

[Ledum 7]

[Rhody 1]

[Ledum 8]

[Rhody 2]

[Ledum 9]

[Ledum 10]

[Ledum 11]

[Ledum 12]

[Ledum 13]

[Ledum 14]

[Rhody 3]

[Ledum 15]

[Ledum 16]

[Ledum 17]

[Ledum 18]

[Ledum 19]

[Rhody 4]

[Ledum 20]

[Ledum 21]

[Ledum 22]

[Ledum 23]

[Ledum 24]

[Ledum 25]

[Ledum 26]

[Ledum 27]

[Rhody 5]

[Rhody 6]

[Ledum 28]

[Ledum 29]

[Ledum 30]

[Ledum 31]

[Ledum 32]

[Rhody 7]

[Ledum 33]

[Ledum 34]

[Ledum 35]

[Ledum 36]

[Ledum 37]

[Rhody 8]

[Ledum 38]

[Ledum 39]

[Ledum 40]

[a]

[Ledum 41]

[Ledum 42]

[Ledum 43]

[Ledum 44]

[Ledum 45]

[Ledum 46]

[Ledum 47]

[Ledum 48]

[Ledum 49]

[Rhody 9]

[Ledum 50]

[Ledum 51]

[Ledum 52]

[3]

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