Herbs & Plants

Rhododendron japonicum

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Botanical Name :Rhododendron japonicum
Family: Ericaceae (er-ek-AY-see-ee) (Info)
Genus: Rhododendron (roh-do-DEN-dron) (Info)
Species:japonicum (juh-PON-ih-kum) (Info)
Kingdom Plantae – plantes, Planta, Vegetal, plants
Division:Tracheophyta – vascular plants, tracheophytes
Subdivision:Spermatophytina – spermatophytes, seed plants, phanérogames
Order: Ericales

Synonyms:  R. metternichii. Sieb.&Zucc.

Common Names: Japanese azalea

Habitat :Rhododendron japonicum is native to E. Asia – Japan. It grows in the dense woods in mountains in C. and S. Japan, to 1800 metres.

Rhododendron japonicum is a deciduous Shrub growing to 2 m (6ft 7in).
It is in flower from Apr to May. The flowers are hermaphrodite (have both male and female organs) and are pollinated by Insects.


Leaf type:the leaf blade is simple (i.e., lobed or unlobed but not separated into leaflets)

Leaves per node:there is one leaf per node along the stem

Leaf blade edges:the edge of the leaf blade has no teeth or lobes

Leaf duration:the leaves drop off in winter (or they wither but persist on the plant)

Armature on plant:the plant does not have spines, prickles, or thorns

Leaf blade length: 40–100 mm

Leaf stalk:the leaves have leaf stalks

Fruit type (general):the fruit is dry and splits open when ripe

Bud scale number: there are three or more scales on the winter bud, and they overlap like shingles, with one edge covered and the other edge exposed
Succeeds in a most humus-rich lime-free soils except those of a dry arid nature or those that are heavy or clayey. Prefers a peaty or well-drained sandy loam. Succeeds in sun or shade, the warmer the climate the more shade a plant requires. A pH between 4.5 and 5.5 is ideal. This species is closely related to R. molle and perhaps not distinct from it. Succeeds in a woodland though, because of its surface-rooting habit, it does not compete well with surface-rooting trees. 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. 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. Plants in this genus are notably susceptible to honey fungus.
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. 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. Cuttings of half-ripe wood, August in a frame. Difficult
Edible Uses: …Leaves. No more details are given but some caution is advised, see the notes above on toxicity.

Medicinal Uses:
Diuretic, tonic

Known Hazards; Although no specific mention of toxicity has been seen for this species, it belongs to a genus where many members have poisonous leaves. The pollen of many if not all species of rhododendrons is also probably toxic, being said to cause intoxication when eaten in large quantities.

Disclaimer : The information presented herein is intended for educational purposes only. Individual results may vary, and before using any supplement, it is always advisable to consult with your own health care provider.

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