Rhododendrons & Azaleas

European Rhododendron Yellow Azalea European Rhododendron Hybrid Rhododendron

What are they?

The heath family is well known for its dislike of chalky soil, for carpeting great swathes of heathland with brilliant colour in late summer and for providing a number of our garden ornamental plants. Apart from their love of acid soils, the members of this family are rather diverse, but most are woody trees, shrubs or low subshrubs and most have flowers that have the five petals fused together to form a flask-like tube. This page covers the rhododendrons, which are rather different to other members of the family in their large and colourful flowers and in often growing to quite sizeable bushes (even trees in some cases). The group includes both evergreen and deciduous species and many are popular as garden ornamentals with a huge number of hybrids having been created in cultivation.

Where are they found?

The European Rhododendron has been widely introduced as an understory plant in wooded areas on acid soils, from where it has rapidly spread to be a highly successful, invasive alien. Other species and varieties of Rhododendron occur occasionally where planted in woodland on private estates or occasionally as relics of cultuvation.

Identification

Almost all plants found are likely to be the European Rhododendron, but others do occasionally occur and should be taken into consideration. Flower shape and colour will be important to confirm identification, along with leaf detail, including leaf shape and size, plus the presence of any hairs and their colour.

NOTE: Plants in the UK included under Rhododendron ponticum have more recently been found to include a range of introgressed hybrids involving R. ponticum and a cluster of Asian and North American species currently in cultivation. It is thought that these hybrid events are at least in part resonsible for the vigour of many plants in the wider countryside. So far, the presence of these hybrids - lumped under the name of Rhododendron x superponticum - does not seem to have been confirmed in East Anglia but this may simply be through a lack of looking. The hybrids can be told by the presence of hairs on the calyx lobes and sometimes on the underside of the leaves.



European Rhododendron      Rhododendron ponticum

Introduced from southwest Europe and now widely found in wooded or heathy areas on acid soils. Highly invasive (but see note above) and vigorously controlled in a number of places. Flowers May to June. A many-stemmed, large bush or small tree, to 5m in height. Stout, leathery, evergreen leaves. Flowers in various shades of pinkish-purple, with orange, yellow or greenish spots.

European Rhododendron European Rhododendron European Rhododendron European Rhododendron
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European Rhododendron European Rhododendron European Rhododendron European Rhododendron
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Seed capsules
Young growth


Hybrid Rhododendrons     

Introduced as garden ornamentals, mostly from China and the Himalayan region, then extensively crossbred in cultivation to produce a huge range of forms. Common in cultivation on acid soils and just occasionally found as garden throw-outs or survivors from old plantings. Flowers May to June. A great range of forms is covered here, from low, ground-hugging plants to species that may attain 10m in height and with flower colours from white, through pinks and purples, to reds, with or without spots.

Hybrid Rhododendron Hybrid Rhododendron Hybrid Rhododendron Hybrid Rhododendron
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Hybrid Rhododendron Hybrid Rhododendron Hybrid Rhododendron Hybrid Rhododendron
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Yellow Azalea      Rhododendron luteum

Introduced as a garden ornamental from SE Europe/Asia Minor and occasional found persisting where originally planted in woodland. Flowers May to June. A deciduous shrub to 4m in height. Leaves 6-12cm long, rolled inwards when young and opening flat.

Yellow Azalea Yellow Azalea Yellow Azalea Yellow Azalea
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Yellow Azalea Yellow Azalea Yellow Azalea Yellow Azalea
Winter twig
Winter terminal bud
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Bark