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Rhododendron - Rhododendron ponticum Biodiversity High Risk

ReproductionIt can reproduce by both sexual (seed) and asexual (vegetative) means. Each flower head can produce unto 7,000 seeds.


Rhododendron seeds can be dispersed by wind up to 100 metres.


It is also capable of reproducing by suckering from roots and by layering wherever branches touch the ground. 

Rhododendron - Rhododendron ponticum Flower Petals

Rhododendron Flower

Rhododendron is a large perennial evergreen, acid loving shrub which is native to the Iberian Peninsula and Asia. It was introduced to Ireland during the 18th Century as an ornamental garden plant because of its attractive flowers.


There are over 900 species of Rhododendron, but only Rhododendron ponticum is invasive in Ireland.


Since its introduction, Rhododendron has escaped into the wild and is particularly invasive in the west, north-west and south-west of the country. Rhododendron thrives on acidic soil in areas with mild, moist climatic conditions.


It can colonise a range of habitats including agricultural land, grasslands, woodland, urban areas, roadsides and wastelands 

How To Identify Rhododendron?

Flower: Purple flower

Leaf: Deep green waxy leaf 

Stem: Woody and tangled

Rhododendron - Rhododendron ponticum Large Stand
Rhododendron - Rhododendron ponticum Leaf and Flower Bud

Rhododendron invasive stand

Rhododendron - Rhododendron ponticum ID Guide

Rhododendron - Rhododendron ponticum ID Guide

Rhododendron leaf

Why Is Rhododendron A Problem?

Rhododendron is an aggressive coloniser which is both environmentally and ecologically damaging to infected sites.


Once established, it forms dense, long-lived thickets which smother the ground flora and suppress the regeneration of native trees and shrubs. Its dense thickets can reach several metres in height.


Well established thickets eventually form a toxic layer of leaf litter which produces a dark sterile environment and supports little wildlife.


The foliage of Rhododendron is unpalatable to grazing animals. Dense tangles of Rhododendron stems can block pathways, smother watercourses and encroach on roadways, resulting in an impingement of sight- lines.


In some cases, infestations have been so expensive to control that land has been abandoned. 

Rhododendron - Invasive Species Information

What Is Rhododendron - (Rhododendron ponticum)?

Distribution in Ireland: Extensive

Family name: Ericaceae

European Communities (Birds and Natural Habitats) Regulations 2011 non-native invasive plant species A-Z (Updated 2017)

There are currently 35 invasive plant species listed in the European Communities (Birds and Natural Habitats) Regulations (annex 2, Part 1)...


Click on a species from the following list to find out more regarding non-native species subject to restrictions under Regulations 49 and 50.

  1. American Skunk-CabbageLysichiton americanus

  2. Brazilian Giant-RhubarbGunnera manicata

  3. Broad-Leaved RushJuncus planifolius

  4. Cape PondweedAponogeton distachyos

  5. Cord-GrassesSpartina (all species and hybrids)

  6. Curly Waterweed - Lagarosiphon major

  7. Dwarf Eel-GrassZostera japonica

  8. FanwortCabomba caroliniana

  9. Floating PennywortHydrocotyle ranunculoides

  10. Fringed Water-LilyNymphoides peltata

  11. Giant HogweedHeracleum mantegazzianum

  12. Giant KnotweedFallopia sachalinensis

  13. Giant-RhubarbGunnera tinctoria

  14. Giant SalviniaSalvinia molesta

  15. Himalayan BalsamImpatiens glandulifera

  16. Himalayan KnotweedPersicaria wallichii

  17. Hottentot-FigCarpobrotus edulis

  18. Japanese KnotweedFallopia japonica

  19. Large-Flowered WaterweedEgeria densa

  20. Mile-a-Minute WeedPersicaria perfoliata

  21. New Zealand PigmyweedCrassula helmsii

  22. Parrots FeatherMyriophyllum aquaticum

  23. Red AlgaGrateloupia doryphora

  24. RhododendronRhododendron ponticum

  25. SalmonberryRubus spectabilis

  26. Sea-Buckthorn Hippophae rhamnoides

  27. Spanish Bluebell Hyacinthoides hispanica

  28. Three-Cornered LeekAllium triquetrum

  29. WakameUndaria pinnatifida

  30. Water ChestnutTrapa natans

  31. Water FernAzolla filiculoides

  32. Water LettucePistia stratiotes

  33. Water-PrimroseLudwigia (all species)

  34. WaterweedsElodea (all species)

  35. WireweedSargassum muticum

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