Irish gardeners, plant breeders and plant hunters are worthy of celebration today
Hail glorious St Patrick's cabbage . . . Well, it being the day that's in it, there's only one thing to talk about. Irish plants. The "real" St Patrick's cabbage, in case you wondered, is a little plant found mainly in the west of Ireland - with a rosette of succulent leaves, and delicate sprays of pretty pink flowers. But the plant most commonly known by that name is a related garden hybrid (Saxifraga x urbium), known also as London pride, and it is by no means uniquely Irish.
As it happens, the shamrock isn't particularly Irish either - it is widespread over Europe and elsewhere. Actually, I should say "shamrocks", because there is no single species that can be exclusively identified as the three-leafed emblem. According to a survey carried out in 1988 by Charles Nelson and the National Botanic Gardens, yellow clover (Trifolium dubium) and white clover (T. repens) are the most common, but red clover (T. pratense), black medick (Medicago lupulina) and even wood sorrel (Oxalis acetosella) have all been used.
The species that is grown now by commercial growers here is yellow clover, which is native throughout Europe, in north Africa and in western Asia.
I'd still like to celebrate Irish plants today - but this means turning our backs on the wild for a few minutes, and casting our eyes around our gardens. Observant gardeners know that some plants are fairly promiscuous, breeding with related varieties, and occasionally creating interesting offspring. Sometimes plants also spontaneously mutate, suddenly throwing out "sports". This genetically divergent material might arise by seed, or even when a bud decides to behave in a different way to the rest of the plant, producing a shoot with distinctive flowers or leaves. The trick is to keep one's eyes open for anything unusual - which is how sharp-eyed Irish gardeners have discovered some fine crosses and sports.
One of the more recent Irish cultivars, which has been snapped up by gardeners in Europe and north America, is a dainty navelwort (I know, it's hard to imagine anything with such a name being delicate, but the "navel" refers to the shape of the seed capsule and "wort" simply means soft-stemmed plant). Omphalodes cappadocica is a Turkish woodlander, and the variety, 'Starry Eyes', was discovered by Rathfarnham gardener, Eithne Clarke, at Woodtown Park in the 1980s. Its azure flowers are rimmed by the palest blue.
In the southwest, Griselinia littoralis 'Bantry Bay' originated from a single aberrant branch on a shrub of the New Zealand evergreen, planted at Ilnacullin on Garinish Island, off Glengarriff in west Cork. The unadorned species is often used as hedging, and is recognisable by its waxy, pea-green leaves. The foliage of 'Bantry Bay' is heavily flamed and splotched with cream and pale green. To my eyes it is an ugly, splashy-dashy brute, but to others it is a thing of beauty - and so must it have appeared to Murdo MacKenzie, the gardener at Ilnacullin, who first spotted it in 1950. To be fair, I suppose it should be cherished as an Irish oddity.
A variegated evergreen that does get my vote, however, is Pittosporum tenuifolium 'Silver Queen', with grey-green leaves elegantly margined in cream. It probably arose in Castlewellan, Co Down, and it was propagated and sold at Slieve Donard Nursery in Newcastle, Co Down.
Slieve Donard was renowned for its dwarf Dierama: cultivars of the South African wand flower, or angel's fishing rod. According to Charles Nelson's encyclopaedia of Irish garden plants, A Heritage of Beauty, almost all the Donard Dierama cultivars are now extinct, but some of the nursery's other introductions survive, including the blue poppy, Meconopsis 'Slieve Donard', and some potentillas and escallonias. The nursery introduced new material not just from its own beds, but from many northern Irish gardens, including Castlewellan and Rowallane.
Northern Ireland was also famous for its rose breeders, the Dicksons and the McGredys. The latter family opened a nursery in Portadown in 1880, and produced its first award-winning roses a couple of decades later. The operation was moved to New Zealand in 1972, where it still flourishes. McGredy roses include the climbing trio: 'Galway Bay' (rose-pink flowers), 'Bantry Bay' (pink) and 'Dublin Bay' (blood red), as well as the popular pink floribunda 'Sexy Rexy' and the rare, and aptly named 'Brown Velvet'.
And, while we're celebrating the Irish today, let's not forget the intrepid plant hunters who came from this country: Dundalk's Thomas Coulter, who introduced the white tissue-paper California poppy, Romneya coulteri, to cultivation; Lieut Col Edward Madden, who sent seeds and plants from India in the mid-19th century; and of course, Augustine Henry, who, 100 years ago, discovered more than 1,500 new plant species and varieties in China.
• The Irish Garden Plant Society is devoted to plants with an Irish connection, Irish garden history and related matters. Membership (€25) is open to all. IGPS c/o The National Botanic Gardens, Glasnevin, Dublin 9. A Heritage of Beauty, an illustrated encyclopaedia of the garden plants of Ireland, by Charles Nelson, is available from the IGPS at €15 (plus €8 p&p)