The wild poinsettia is an entirely different kettle of fish from the showy potted plants that mount an annual Yuletide invasion on our garden centre shelves. In its natural habitat in Mexico, the red-bracted Euphorbia pulcherrima is a stately - some might say, straggly - shrub, up to 4 metres in height. Modern science, through breeding, selection, dwarfing compounds and artificial day-length has given us the plants that have become as indelible a part of Christmas as mince pies and head-aches.
Fourth generation nurseryman Peter Byrne grows poinsettias by the barrow-load under an acre of glass near Brittas Bay in Co Wicklow. He's trying out 11 new varieties in his father's garden centre, Harry Byrne's in Sandycove, where they cost £7.35. Among these are `Snowcap' and `Freedom' (both with white bracts), `Cortez' (hot pink) and `Silver Star' (dark red with a variegated leaf).
Harry Byrne's has many other festive house plants including the trailing, tubular-belled Columnea (£7.50) and the rather rude-looking Anthurium (£15 - £20), both originating in tropical America. There are also seasonal fleets of cyclamens, a good number of orchids (£11.95 - £29) and citrus plants such as kumquats, oranges, lemons and grapefruit (up to £55).
Next door, in Mackey's, there are camellias in a range of sizes (£15 - £75). Besides the large-flowered C. japonica and C. x williamsii hybrids, there is an early-flowering C. sasanqua (£99) with delicate, palepink blooms - a more understated plant than its bold relatives. (It's worth noting here that in cold weather, frost-bitten camellia flowers can be damaged by over-quick thawing, so the accepted wisdom is not to plant them in an east-facing position where they may be warmed up too swiftly by the morning sun. Camellias also like a moist soil: if planted in a sunny position, mulching and watering is essential to avoid buds dropping off.)
As always, Mackey's has lots of lovely topiary: small box balls (£19.95), bay lollipops and pyramids (£85), and small-leaved Chinese privet (Ligustrum delavayanum) trained into lollipops (£50 and £95). Darklyhandsome, columnar box-leaved holly (Ilex crenata `Fastigiata') grows naturally into slim pillars, and would make a terse, no-nonsense statement outside a smart front door (£40.95).
Natty geometric plants are the speciality of Formality in Dun Laoghaire, including hard-edged box cubes (£65) and an extravagant swallow (£340), ready-tailored out of Chinese privet - for the ornithologist who has it all. Tree ferns, which lend an expensive, tropical tone to a shady, sheltered corner cost from £70 to £500.
Avoca Nurseries at Kilmacanogue, Co Wicklow, opened earlier this year, yet another facet to the many-sided Avoca Handweavers' business. It's a pet project of owner Donald Pratt, an enthusiastic man of the soil. He has a team of gardeners propagating and growing on plants in the lightfilled glasshouses that glow yellowly over the N11 dual carriageway.
Avoca has an extensive - but fast diminishing - stock of citrus trees, including ornamental standards (£55 - £70). I also noted neat little bonsai trees for £8.70, numerous different streptocarpus (£3.90), azaleas (£4.99), camellias (£7.95 and £11.95) and hibiscus (£9.50).
DISCERNING Dublin gardeners eventually end up in Murphy and Wood on Johnstown Road in Cabinteely. Their Christmas offerings include orchids (from £15 to £25): not just the usual pretty-pretty Phalaenopsis and Cymbidium, but the acid-yellow Oncidium and the challenging Dendrobium also. Genuine dwarf conifers that don't turn into monsters when your back is turned are the cultivars of Pinus mugo with the undignified handles of `Mops' and `Humpy' (£14.50 and £16.55).
And, although Japanese maples are minus their leaves by the time Christmas rolls around, many varieties will set the heart of most gardeners a-flutter. Murphy and Wood have at least 15 different types (from £15 £125) including `Red Pygmy' and `Shindeshojo'. The latter has brilliant-red new foliage maturing to red-veined green and finally turning to orangey-red as the nights get colder.
In Cork, Con O'Sullivan's of Blarney gets the vote of keen plants-people as one of the best places for interesting outdoor plants. "I go nowhere else now and meet a lot of the local gurus there," says one keen Corkonian. Japanese maples do especially well in the south's moist climate and Mr O'Sullivan's nursery always keeps a wide assortment. `Seiryu' (£22.50) has a finely-dissected leaf, bright green in summer and crimson with orange and yellow splashes in autumn. `Chishio', also known as `Shishio' (£18.75), is another chameleon-like maple, going from red to green and back to red.
Camellias grow wonderfully in Cork, and their slightly over-the-top blossoms look at home in the comparatively lush vegetation in that county. O'Sullivan's carries 20 or 30 different varieties (£8.50 - £17.50).
Of course, there are excellent garden centres and nurseries all over Ireland, and many are filled to the gunwales with tempting plants aimed at the Christmas market. Some words of caution: make sure that the plant you buy suits its eventual environment. The beautiful bougainvillea, for instance, with its shocking-pink, petal-like bracts certainly conjures up memories of happy holidays in sunny climes - but "sunny" is the key word. If there is no conservatory or porch at the bougainvillea's potential home, don't buy it.
The same goes for most citrus plants - although calamondins (miniature, sour oranges) are happy in a bright living room, if misted regularly. Streptocarpus, cyclamen, poinsettias and orchids are tolerant of the light conditions in most houses.
Obviously before you buy, check that all plants are healthy and free from pests or diseases. Take a moment to examine the compost (should be slightly moist) and the undersides of the leaves (definitely no critters). And, finally, if you buy an outdoor plant for a Christmas gift, please don't bring it into the warm, dry, uncongenial house for longer than the couple of hours, if you value its health. Remember: a plant can be for life, not just for Christmas.
Jane Powers is at jpowers@irish-times.ie