Curiosity value takes sting out of this plant

Press, 4 May 1984, Page 11

Curiosity value takes sting out of this plant

ARDENER’S ! DIARY

Derrick Rooney

I first came across the name “Blumenbachia” in the “Autumn and Winter” volume of E. A. Bowles’s gardening classic about his garden near the New Forest.

Recently I was reminded of it when I took a seasonal dip into the book. So when I spotted this pretty stinging plant growing in a friend’s garden I wasn’t backward in asking for a pinch of seed.

He did better than that, and came forward with a brace of seedlings.

Now I have the task of finding a sheltered, but out-of-the-way, corner for them where no-one will have to brush against them, and I won’t be in any danger of grabbing a fistful of minute hypodermic needles while weeding. Though the blumenbachias must be reasonably hardy if Bowles was able to grow them at Myddelton House, they are of subtropical origin and not to be taken casually in frosty areas.

Part of their appeal to Bowles lay in the extraordinary structure of the venom-filled stinging hairs which cover all the aboveground parts of these plants; another part of the appeal was the curious construction of the seedpods. These are in segments tightly arranged in a spiral, so that a ripening fruit looks like a light bulb mounted on a centrifuge.

There are several, perhaps seven or eight, species, in cultivation and probably more in Central and South America, to which they are confined in their natural state. I’m not sure which of the species is mine; it has pretty soft orange flowers. The blumenbachias, whose name commemorates a noted German anatomist of the early nineteenth century, belong to a family of New World climbers called the Loascaeae. One of the characters of this family is that its members tend to ,have showy flowers.

Another is the stinging hairs, which cover all above-ground parts of the plant, including (and this is unusual) the flowers and fruit.

One of E. A. Bowles’ friends, tired of continual filching of his prize blooms,

grew species of Loasa over the climbing roses in his driveway, hoping that their armament would deter would-be thieves.

I don’t have a driveway lined with roses, nor do I normally have a filching problem, but there are times wheen I think something like a loasa or a blumenbachia might be useful — such as when I intercepted a garden club members from one of the snootier Christchurch suburbs at the gate with a branch she had tom from a flowering shrub. She looked quite offended when I told her she couldn’t keep it. Fortunately, most visitors have better manners.

Another newcomer for which I must find garden space is also South American.

This is Tropaeolum pentaphyllum, one of the dainty perennial climbing cousins of the common garden nasturtium, a plant which, despite fussing and coddling, refuses to grow in our garden, though it is rampant in the disused rubbish dump less than a mile away in the riverbed, where it flings flowering trailers in all directions among the stones.

I was once told that if you train a nasturtium up an apple tree you will have no trouble with the woolly aphids which cluster on the stems of some apple trees, causing large, ugly galls to develop.

So far I haven’t been able to put this theory to the test, (a) because there is no wooly aphis in my garden and (b) because the nasturtiums don’t grow. I suppose their recalcitrance is because I have declined to accept their title to the name “nasturtium,” which long ago became attached to them by some involved process of nomenclatural confusion which I have given up trying to unravel.

Garden “nasturtiums” are tropaeolums, a group of

plants with long-spurred flowers, like little dancing birds. The only plant truly entitled to the name “nasturtium” is the common watercress, which belongs to the same family as cabbages and radishes. The common “climbing nasturtium” is Tropaeolum majus.

Oddly enough, gardeners are happy to use the name “tropaeolum” for the perennial members of the family, one of which, Tropaeolum speciosum, is widely naturalised. Another name for this pretty flame-coloured flower is “Scottish creeper,” and although it is of Chilean origin it is mainly a plant of the cooler “Scottish” provinces — Otago and South-

land. Other members of the family are less well known. I grew one of them — Tropaeolum tuberosum — for a while, but found it rather sensitive to frost and caterpillars, and eventually gave it away to a friend with a warmer town garden, where it thrives. I saw a mass of its near-orange flowers the other day.

Tropaeolum pentaphyllum thrives in the same garden. This is, like its two perennial cousins, a tuberousrooted plant whose shoots will wander sideways beneath the ground for many centimetres, sometimes for metres, before emerging. Though it will climb to two metres up a fence or through a bush, it is very dainty, with small leaves and reddish flowers shorter than a little finger and of about the same diameter.

Like the others, it dies down in winter to a persistent tuber, which is reputedly edible. Last spring I raised a plant of this species from seed, and it grew strongly throughout the summer until one gloomy February day when I knocked its pot down from the bench and decapitated the plant. Though there is a healthylooking young tuber in the pot, there has been no sign of fresh top growth since the accident, but this doesn’t surprise me, because these plants have the ability to lie dormant for a couple of seasons.

In any case, I have since acquired another plant which not only has shoots but is flowering, and if my seedling never shows fresh signs of life I won’t be sorry.

This is, incidentally, reputedly the easiest species to establish in the garden. Tropaeolum speciosum is probably the prettiest, but despite its widespread apCearances in old hedges and ush margins it is not very amenable to cultivation.

I have repeatedly failed in attempts to establish it in my garden, though not two miles away, in an area of blackberry, broom, lupin and other woody weeds marking the site of a longdemolished cottage, the Scottish creeper is rampant over perhaps quarter of an acre, which it lights up with a red glow in summer.