Choice of mahonias, scented or not

Press, 1 September 1989, Page 10

Choice of mahonias, scented or not

Sardener’sll X DIARY ;

Derrick Rooney

A few months ago I chainsawed, to lawnmower height, a frostblasted and wind-battered evergreen (its name does not matter) which not only looked awful, but was casting too much shade on part of the garden. I have just been standing outside, in the rain, feeling good about one of the consequences of this action: a heavy crop of flower buds, and signs of renewed vigour, for the first time in years, in Mahonia repens, which had been having a lean time. This distinguished Californian is a low, creeping shrub which sprouts new stems at irregular intervals from underground runners, so that it forms scattered clumps. Normally, this habit enables it to run away from competition, but on this occasion, surrounded by other plants, it had nowhere to go. Give the poor little thing a chance, I thought.

I would not like to lose it, because it is not common in cultivation and is a more attractive plant, I

think, than its well-known cousin, M. aquifolium, the “Oregon-grape,” which spreads more vigorously and, if the soil is good enough, can make shoulder-high thickets inlight shade. I have Oregon-grape in the garden, but only because a seed was dropped there by a bird which had been feeding on one of the wild patches behind the nearby domain. I donot think I would pur-

posely plant it, because while it is tenacious, hardy, and long-lived, and has pretty yellow flowers, it hardly ranks in the top tier of flowering shrubs nowadays, except perhaps for large gardens with big, old trees, beneath which there is a need for tough plants to fill space. Oregon-grape used to be a rich man’s plant, and back in the 1820 s, when it

was introduced to cultivation, it commanded the princely price of £25, but its high-flying career was abruptly terminated in the 1840 s by the arrival of two superior Asiatic mahonias, M. bealei and M. japonica. The latter two reigned for 90 years until Laurence Johnston, of Hidcote Manor, in Gloucestershire, brought home from Yunnan seeds of M. lomariifolia, which he raised and distributed from his other garden in Menton, France. There is no doubting the quality of M. lomariifolia. W. J. Bean called it the handsomest of the mahonias, and the current English gardening guru, Christopher Lloyd, remarked that it left him “weak and babbling with admiration.” I am less enthusiastic about it. Here, it loses marks because of its habit of flowering in May, which ensures that in four years out of five its display is ruined by frosts. In mild gardens, it is simply spectacular. In colder areas, its hybrid, “Char-

ity,” is a better plant The other parent of “Charity” is M. japonica, which in gardens is often confused with M. bealei. The two are probably not separate species in the true sense, but represent extremes of the variation within the one species. Horticulturaily, they are distinct entites, however. M. japonica has drooping flower spikes; M. bealei has more erect flowers, and broader leaflets, with the terminal leaflet generally noticeably bigger than the others. The young foliage of M. japonica sometimes turns yellow in winter. Both have very sweetly scented flowers. Scent on the other hand is something I do not associate with either M. aquifolium or M. repens, but they have other virtues, including the ability to recover from long

summer droughts. Most of their growth is made in spring. Both are fairly easy to propagate from cuttings, especially if the cuttings include a little bit of underground stem, but sometimes they are slow to grow away. Most mahonias are best planted in their permanent positions as soon as they have strong root systems, and left undisturbed while they get on with growing. All but a few of the lesserknown species will survive transplanting but may look shabby . for several years afterwards.

All the plants of M. aquifolium grown in New Zealand probably stem from a single introduction, but in North America, and especially in Oregon (where the Ore-gon-grape is the official state flower) a number of named varieties are grown, including one with blight red young foliage. There are hybrids with M. repens, too, of which the plant known as M. repens var. rotundifolia

may be one. This is a stout, erect bush, eventually reaching one metre, according to the books. The leaflets are scarcely prickly, and are deep, matt green instead of the typical bluegreen of M. repens. The flowers are a good, bright yellow. If all this sounds too good to be true, it is; although this shrub ought to have hybrid vigour, it can be reluctant to settle in the garden. A friend gave me a sucker from his plant, and it languished for years, until I moved it to a damper spot, in shade; now it is a nice little bush, just beginning to make a thicket and to flower freely, but I predict that it will qualify for the pension before it reaches the projected height of one

metre. Few of the other mahonias — there are about 50 species in all — are in cultivation. They are very closely related to the barberries, but are segregated by their having pinnate leaves and no spines on the

stems (though the leaves are prickly), whereas the barberries all have simple leaves, and stem spines. A third shrubby genus in this family and one which few gardeners would recognise as a cousin of the barberries, is the so-called "Chinese sacred bamboo,’’ Nan-

dina domestica. Most garden centres stock the small-growing form of nandina, known as “Nana Purpurea,” but the original, tall plant is less often seen, although it is a shrub of real quality. The probable reason for this is that the original clone was largely selfsterile, so that although its masses of while flowers were on display every summer it seldom converted them into its brilliant, sealing-wax-red berries. “Richmond,” a New Zealand-raised clone which is now obtainable (at a price) removes this anomaly. It is self-fertile and carries heavy crops of berries, which hold on all winter. Birds do not take them. The “Nana” variety seldom flowers. I do not consider it worth growing.

Oregon-grape once a rich man’s plant

Flowers are a good, bright yellow