Practical
Plants

Rhododendron maximum

Rosebay Rhododendron

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Taxonomy and growth

Family
Ericaceae
Life cycle
perennial
Foliage
evergreen
Woodiness
woody
Height
3.5 m
Fertility
Bees
Flower type
hermaphrodite
Pollinators
Bees

Uses

Toxicity

Toxicity warning. The historical record reports a hazard for this plant. Do not use it to decide which parts are safe to eat or use medicinally.

The leaves are poisonous[5]. Ingestion can cause convulsions and coma[5]. The pollen of many if not all species of rhododendrons is also probably toxic, being said to cause intoxication when eaten in large quantities[2].

Medicinal uses

Historical medicinal uses. These records describe reported uses. They do not establish safety or effectiveness. Ask a qualified health professional before using any plant medicinally.

The poulticed leaves are used to relieve arthritic pain, headaches etc[11][5]. A decoction of the leaves is occasionally employed internally in domestic practice in the treatment of rheumatism[13][8]. The leaves are taken internally in controlled dosage for the treatment of heart ailments[5]. Caution is advised, see the notes above on toxicity.

Product or use
Analgesic
Product or use
Antirheumatic
Product or use
Cardiac

Material uses

Wood - fine-grained, hard, heavy, strong, rather brittle[10][11][13][6]. It weighs 39lb per cubic foot[7]. Used for tool handles and as a boxwood (Buxus spp.) substitute in engraving[10][11][13][6].

Product or use
Wood

Environment

Range
Eastern N. America - Nova Scotia and south to Georgia and Alabama.
Habitat
Damp places along streams, edges of bogs and ponds, woods and mountain slopes to 900 metres[9][3], often forming impenetrable thickets[7].
Shade tolerance
partial shade
Water
moderate
Hardiness
Zone 3+
Soil textures
sandy, loamy
Soil pH
very acid, acid
Drainage
well drained
Tolerates Nutritionally Poor Soil
No
Drought
intolerant

Propagation

Seed - best sown in a greenhouse as soon as it is ripe in the autumn and given artificial light. Alternatively sow the seed in a lightly shaded part of the warm greenhouse in late winter or in a cold greenhouse in April. Surface-sow the seed and do not allow the compost to become dry[4]. Pot up the seedlings when they are large enough to handle and grow on in a greenhouse for at least the first winter. Layering in late July. Takes 15 - 24 months[12]. Cuttings of half-ripe wood, August in a frame. Difficult[12].

Cultivation

Succeeds in a most humus-rich lime-free soils except those of a dry arid nature or those that are heavy or clayey[1]. Prefers a peaty or well-drained sandy loam[1]. Succeeds in sun or shade, the warmer the climate the more shade a plant requires[4]. A pH between 4.5 and 5.5 is ideal[1]. Hardy to about -30°c[3]. Succeeds in a woodland though, because of its surface-rooting habit[4], it does not compete well with surface-rooting trees[1]. Plants need to be kept well weeded, they dislike other plants growing over or into their root system, in particular they grow badly with ground cover plants, herbaceous plants and heathers[4]. Plants form a root ball and are very tolerant of being transplanted, even when quite large, so long as the root ball is kept intact[4]. Plants in this genus are notably susceptible to honey fungus[4].

References

  1. F. Chittendon. RHS Dictionary of Plants plus Supplement. 1956 Oxford University Press 1951-00-00

    ↩1↩2↩3↩4

  2. Facciola. S. Cornucopia - A Source Book of Edible Plants. Kampong Publications 1990-00-00 ISBN 0-9628087-0-9

    ↩

  3. Phillips. R. & Rix. M. Shrubs. Pan Books 1989-00-00 ISBN 0-330-30258-2

    ↩1↩2

  4. Huxley. A. The New RHS Dictionary of Gardening. 1992. MacMillan Press 1992-00-00 ISBN 0-333-47494-5

    ↩1↩2↩3↩4↩5↩6

  5. Foster. S. & Duke. J. A. A Field Guide to Medicinal Plants. Eastern and Central N. America. Houghton Mifflin Co. 1990-00-00 ISBN 0395467225

    ↩1↩2↩3↩4

  6. Elias. T. The Complete Trees of N. America. Field Guide and Natural History. Van Nostrand Reinhold Co. 1980-00-00 ISBN 0442238622

    ↩1↩2

  7. Britton. N. L. Brown. A. An Illustrated Flora of the Northern United States and Canada Dover Publications. New York. 1970-00-00 ISBN 0-486-22642-5

    ↩1↩2

  8. Moerman. D. Native American Ethnobotany Timber Press. Oregon. 1998-00-00 ISBN 0-88192-453-9

    ↩

  9. Fernald. M. L. Gray's Manual of Botany. American Book Co. 1950-00-00

    ↩

  10. Uphof. J. C. Th. Dictionary of Economic Plants. Weinheim 1959-00-00

    ↩1↩2

  11. Usher. G. A Dictionary of Plants Used by Man. Constable 1974-00-00 ISBN 0094579202

    ↩1↩2↩3

  12. Sheat. W. G. Propagation of Trees, Shrubs and Conifers. MacMillan and Co 1948-00-00

    ↩1↩2

  13. Sargent. C. S. Manual of the Trees of N. America. Dover Publications Inc. New York. 1965-00-00 ISBN 0-486-20278-X

    ↩1↩2↩3

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