Native Bluebells and Spanish Bluebells in Croydon

The native Bluebell Hyacinthoides non-scriptus is widely distributed in Croydon. It grows in almost every wood and many hedgerows and its flowers make spectacular displays in many of our larger woods in Spring. The garden plant is usually the Spanish Bluebell Hyacinthoides hispanica. This is a larger and more robust plant than the native Bluebell, with broad leaves, and paler blue, more open flowers which stand out around the stem.¹ It was grown in gardens here by 1683 and has been known in the wild since 1909.² Spanish Bluebells may escape from gardens or are dumped with garden rubbish. The two species hybridise to produce plants which are intermediate in character between the parents. The hybrids are fertile and swarms of plants may arise which show a complete spectrum of characters. There is currently concern that the Spanish Bluebell will threaten the native Bluebell population by hybridising with it, and the plant conservation organisation Plantlife has set up a survey of the two species in 2003.³

We noted the occurrence of native Bluebells and Spanish Bluebells in 74 woods and woodland fragments in Croydon during 2000 and 2001. Native Bluebells were found in 71 woods, and Spanish Bluebells or hybrids in 31 woods. The latter were usually in small numbers at the edges of woods or where there was obvious evidence of dumping of garden rubbish. Hybrids may result from dumping or from cross-pollination by insects of garden plants and wild plants in the adjoining woods.

When the occurrence of Spanish Bluebells is tabulated according to whether or not the woods have adjacent houses, the correlation is obvious (χ² [chi-squared] test, statistically significant at P = 0.001). Spanish Bluebells and hybrids are associated more with woods with adjacent houses, and are only occasionally found in woods which do not have houses as immediate neighbours.

Although the numbers of Spanish Bluebells are currently small and the distribution is restricted, it does pose a potential threat to our native Bluebell, and spare plants from gardens should not be planted or dumped in the wild.

Jane McLauchlin and Gwyneth Fookes

References

1. Stace C (1997). New Flora of the British Isles, Second Edition. Cambridge University Press.
2. Preston C D, Pearman D A & Dines T D (2002) New Atlas of the British & Irish Flora. Oxford University Press.
3. Plantlife magazine, Spring 2003.

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Last updated October 7^th 2003
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