Lilies form international family of surprises

Press, 2 September 1983, Page 10

Lilies form international family of surprises

gardener’s I DIARY

Derrick Rooney

The lily family, known to most gardeners as a race of expensive bulbs, actually contains a great diversity of plant types from most of the world’s climatic zones. Among the most interesting of these are the succulent ‘lilies” of South Africa — a group of plants which includes sucn genera as aloe, gasteria, haworthia, and astroloba.

Recently the latter has been a source of much pleasure to me, because a plant which has become a favourite in my small collection of succulents is an astroloba. I grew it from a cutting of a dessicated and near-mori-bund plant in a neglected glasshouse which was being cleared out.

It took years to put flesh on its thin bones, but I now have a handsome, bluishleaved plant from it. Many succulents have this marvellous power of recovery. Once, I bought at auction a batch of flower pots from an estate. One of them contained a shrivelled sedum, which I nursed back to health from a state similarly poised on the brink of death, but the story ended less happily; as soon as the sedum was juicy enough, a passing goat ate it. Aloes can perform marvels of rejuvenation too. For a long time I grew a plant of Aloe Saponaria — one of the larger species — outdoors in a big pot. Every spring I marvelled at the way in which this frostblasted plant burst into renewed growth when the days warmed up in October. Eventually I discarded it, at the cost of torn and bleeding hands.

Whereas most aloes neatly and conveniently drop their dead leaves, this one hangs grimly on to them; they assume the texture and colour of sun-dried leather, and the thorns on the margins get sharper and sharper.

This decided me to stick to the aloes with softer thorns, or unarmed leaves. There are plenty of these, though not many are readily available in cultivation.

Wild aloes cover a wide geographical range throughout the African continent, and are naturalised in the Mediterranean area and in several countries with Medi-terranean-type climates, including New Zealand. They range from trees down to tiny, rosulate alpines. It is the latter kind which is most useful in cultivation. All the aloes have tubular or bell-shaped flowers, in spikes. Gasterias and haworthias are very closely related to them, and a number of intergenaric hybrids are cultivated, though these may not occur in the wild. I have grown a few, and the interesting thing about them is that they lack — or rather, in my growing conditions they lack — the expected hybrid vigour, and' are more sensitive to winter damage than the parents. Despite their close relationship, the three genera are distinctly different. The mildest of amateur growers can easily tell them apart (identifying the species

within each genus is another matter).

Aloes have their flowers regularly arranged in spikes, usually in a coneshaped inflorescence; in individual flowers the corolla is always evenly round. Their typical plant form is a rosette.

Gasterias tend to have their leaves in fans and their flowers in curving, one-sided spikes; individual flowers are usually cres-cent-shaped, and pot-bellied, mostly in green and red shades. Haworthia flowers are alternately* arranged in the spike, and fold back at the mouth so that the corolla has a two-lipped appearance.

The typical haworthia leaf shape is a triangle, but there is considerable variation in their size and shape. My favourite is Haworthia tesselata, one of those curious South African succulents whose leaves have “windows” — areas of translucent tissue between the leaf veins, the purpose of which is assumed to be to filter the powerful desert sunlight, thus preventing damage to the sensitive photo-synthetic mechanism .

inside the leaf. The veins between the “windows” are dull reddishbeige, and the whole leaf is a superb example of natural camouflage: put the plant in a pot mulched with sandstone gravel and it becomes nearly invisible. This, too, is a protective mechanism — against browsers in the arid, sparsely vegetated areas where these plants grow. Many of the aloes are so large that they can be accommodated only in a very big glasshouse, or out in the garden in frost-free areas. Small species do exist, and on the whole are hardier than their larger cousins. I’ve often wondered why they haven’t become more popular. Aloe aristata is a good one, clump forming and perfectly happy in a pot or in a sharply drained spot outdoors where it will prove perfectly hardy. The leaves are purplish-beige, and the flowers vermilion red. Aloe humilis, similar in size, a shade less hardy, and with bluish leaves, has coral-red flowers. Aloe tenuior, rather larger and needing a big pot or a spot outdoors against a wall or fence, tends to climb, and though often classified as tender is fairly hardy — I have seen it growing undamaged outside as far inland as Windwhistle. It has yellow flowers. More useful to the grower with limited frame space are a number of miniatures, some of which I maintained for years, in an apparently healthy state, in Bcm pots. Aloe jacksonii, with bright yellow flowers, is one; A. parvula, with lovely bluish rosettes, is another. For some years I have grown these, and a number of hybrids of both these and other — unknown — species. They came from a collection which was being broken up, and do not seem to be available from the few succulent nurseries, unfortunately. An interesting feature of these plants is that most of them flower in winter, just

when colour is in greatest demand.

I don’t think they would be hardy outdoors, but they survive and flower well in my succulent frame.

A measure of their hardiness is this: apart from the corrugated fibreglass light, the only frost protection they receive is an old carpet, which is tossed over the frame on frosty nights. When the temperatures are very low this is not sufficient to exclude frost, and sometimes on winter mornings the soil in the pots is frozen solid.

Surprisingly, losses among them have been light.

In their native home, such rain as falls would come in winter, but they would rarely be exposed to heavy frost, such as we get in Canterbury. In summer they would be dry. The result of this is that their growing is done in the cooler months. No matter how they are treated in cultivation it isn’t possible

to break them of the wintergrowing habit. However, they can be manipulated so that they grow mainly in the very early or very late winter, thus easing the problem of maintaining them through the worst of the frosts. A number of curious and beautiful winter-growing succulents from the western Cape Province and Namibia — especially in the crassula family — can be managed in this way, and it is surprising how they will grow and flower in low temperatures.

I had several of these in flower at the start of winter, and a number are coming into flower now. None of them will survive prolonged periods of cold combined with dampness, though, and if you haven’t got a heated glasshouse from which frost can be excluded — they need no more than that — you have to be very careful in your treatment of them. The technique used to be known as “starvation cultivation.” I will have more to say about it later.