Tuesday 17 October 2017

Diarmuid Gavin: 'Carnivorous plants can add a splash of beauty to the garden while stirring the imagination of children'

Sarracenia flava rubricorpora
Sarracenia flava rubricorpora

Diarmuid Gavin

Carnivorous plants aren't a group that we tend to give a great deal of attention to in our gardens, sometimes regarding them as children's curiosities or an invention of science fiction.

However, if we do ignore them, we are missing out on some fascinating species which have evolved over many thousands of years, and which have fairly distinctive characteristics involving amazing mechanisms they have developed to trap insects - and in some cases small animals. They're not completely alien to us, there are even species native to Ireland which grow freely in some parts of the country.

As a method of engaging youngsters with the wonders of horticulture and the plant kingdom, they have no equal. Young eyes widen in amazement as the Venus flytrap snaps its jaws tight on its victim. Imagine, plants that could possibly eat insects and maybe even small animals!

One of the roles of our National Botanic Gardens is taxonomic research into Irish and world flora. In recent years the director, Matthew Jebb, has co-published 12 new species of the carnivorous Pitcher Plant genus Nepenthes.

Some of these had been collected nearly a century ago, others more recently. All come from the Philippines, which is now one of the most diverse islands on Earth for these plants.

Some of these have been named after their islands of origin, including Leyte, Negros, Ramos and the Samar Islands. Others have been named after mountains (Mt Kitanglad and Mt Alzapan) and a couple are named after other botanists (Shigeo Kurata and F Cid). Many carnivorous plants are also very beautiful with quite remarkable foliage and flowers. Sarracenias (above), for example, commonly known as pitcher plants, are among the most hardiest - especially Sarracenia purpurea, the purple pitcher plant. They attract prey by emitting a sweet nectar.

Creatures enter the plant tempted by the nectar and lose their footing on the waxy surface, slipping to the bottom of the funnel-shaped vessel where they are digested by plant enzymes.

From the wetlands of North America, this plant has been known to devour frogs and lizards as well as slugs and insects!

Their insect-eating ability is a natural adaptation to growing in very low nutrient boggy soil where there is little other nourishment to be found.

So if you wish to grow these in your back garden, those are the conditions you need to mimic. This could be the edge of a pond that is naturally wet, or you can create an artificial bog with pond liner, punctured with some holes for minimal drainage. You will need a mixture of peat or coir, and perlite or washed sand to create a low-nutrient compost.

They like to be in the sunshine and you can also grow them in containers on windowsills or in glasshouses, but need to keep their roots permanently in water. They won't need feeding - they will survive on insect life alone! If keeping indoors, only use rainwater to water as our hard tap water will be too alkaline for them.

They will also need a cold period in the winter to rest so move to an outdoor cold area such as an unheated glasshouse or shed for a period. Other hardy sarracenias include S flava, the elegant yellow pitcher plant, and S leucophylla, the white trumpet which has exquisite white markings at the top of the pitcher, and all have very beautiful nodding flowers in spring.

The common butterwort (left), Pinguicula vulgaris, a British native, is also an insectivorous plant. Its fleshy leaves are ­covered in a gluey substance which traps insects that have the ­misfortune to land on them. They are then slowly consumed by the plant's excretions.

Growing wild in bogs, they produce a lovely bright violet flower. Growing conditions indoors and outdoors will be similar to Sarracenias - boggy, low-­nutrient conditions - but they would like some shade during the day.

Gardening experts

Expert organic grower Klaus Laitenberger will join Anja Gohlke (head gardener at Kylemore Abbey) and Síle Nic Chonaonaigh for a gardening weekend in Connemara from May 5-7 at the Renvyle House Hotel. For further information visit renvyle.com

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