Nature on our doorsteps: Spanish Bluebells – a problem or not?

Rosaleen Dwyer is the County Heritage Officer at South Dublin County Council – every week she gives us an insight into nature on our doorsteps and the beautiful biodiversity of its plants and wildlife.

WHILE Bluebells are generally widespread in Ireland, they are a threatened species throughout Europe.

It is important therefore to protect the habitats in Ireland where Bluebells thrive, including woodlands, old hedgerows, scrub, and shady roadsides and riverbanks. These habitats are often lost to development and agriculture.

Bluebell habitats are also threatened by invasive non-native plants like Japanese Knotweed and Himalayan Balsam.

These can grow and spread rapidly through Bluebell habitats, competing with them for space and soil nutrients.

Another threat has been highlighted in recent years.

The Spanish Bluebell is a non-native garden variety of Bluebell that was introduced by the Victorians. It does very well in gardens, but when it spreads into local habitats it reduces the area where native Bluebells can grow.

Spanish Bluebell can also cross-pollinate with native Bluebells, producing hybrid Bluebells which contain genes from both parents.

Hybridization often causes the reduction in fertility of one or both plant parents, where fewer or no seeds are produced.

The stems of the native Bluebell arch gracefully to one side

This could affect the ability of native Bluebell populations to survive into the future.

Recent scientific studies in Britain have investigated these concerns.

Genetic tests of Bluebells across Britain discovered that the original ‘Spanish’ Bluebell is in fact a plant that originated in Portugal, not Spain.

Also, it appears that what we call Spanish Bluebell today is a hybrid species itself.

They were formed at the time that the Portuguese plants were first introduced to Britain, when they were either accidently or deliberately hybridized with native Bluebells.

The studies indicate that because the pollen grains of this hybrid are not well-formed and are often unhealthy, the plants do not produce many seeds.

This suggests that Spanish Bluebells are therefore unlikely to completely dominate native Bluebell habitats.

However, as the pollen of Spanish Bluebells are often unhealthy, this may be a problem for pollinating bees who need all the protein and minerals that healthy pollen offers in springtime.