SAXIFRAGA (saxifrage, rockoil)

There are about 370 species in this genus, many being excellent plants for growing in pans in an alpine greenhouse. Many of these could be experimented with on window-sills, provided the situation is very bright and airy. Little more than frost-free conditions are required. However, the most popular houseplant is undoubtedly S. stolonifera (syn. S. sarmentosa), which is a very old favourite and has acquired a number of common names. For example, mother of thousands, strawberry geranium. pedlar’s basket, and rowing sailor. It is a creeping and trailing plant, sending out long runners with reddish stems. The foliage is roundish, with irregular edges, silvery veining, green above and reddish below, and slightly hairy. The form ‘Tricolor’ has the foliage variegated with creamy-yellow and pink, and is very pretty. Unfortunately, it is rather less vigorous and is best kept slightly warmer than the minimum 5 deg C (41 deg F) needed for the type species. The plants are excellent, for hanging pots or small baskets, and for pedestals or for trailing over the edges of troughs. A characteristic is that the stems produce numerous plantlets complete with roots, hence the name mother of thousands. These plantlets can be detached and used for propagation by potting them separately.

In the form ‘Tricolor’, plantlet production is very much reduced. Both these saxifrages should be given a shady posi-

tion and kept well watered and humid during summer. A spray with a mist of water from time to time is beneficial. A loam-based potting compost, such as John Inncs. with a little extra washed grit, forms an excellent medium. In winter, water should be applied very sparingly and the air kept drier. The best time for potting is spring, but when carrying out this operation do not press the compost down too firmly. In positions where there is too much light, the foliage may bleach and fall. However. the plants do not like excessive gloom. Of the many other saxifrages, one that is achieving more popularity as a house-plant is.S. cotyledon, which is quite hardy and suitable for bright but chilly places in the home. It forms a dainty rosette of narrow foliage which has a lime-like encrustation along the margins. It is native to the Pyrenees. A special attraction are the flowering stems that arise well above the rosette all summer. These bear graceful sprays of numerous pure white flowers and are very pretty. However, they sometimes need support and this is best done using thin split-cane, or very thin stiff wire. After flowering, remove the remains of the stems cleanly and put the pots outdoors, preferably with the pots plunged and where it is slightly shaded. New rosettes will usually form. Before the first frosts, bring the plants back into the home and put them in a

cool place. The best time to remove young rosettes for propagation is in April and May. They should be treated like cuttings and rooted in a peat and grit mixture. Water sparingly at lirst and do not apply water freely until the cuttings are well rooted, which may take almost a year. This species likes a well-drained rather alkaline compost, and John Innes potting compost with some limestone grit added is suitable. A very desirable form of this species with white flowers daintily speckled with red can sometimes be obtained; the stems are more arching in habit.

S. stolonifera is liable to attack from aphids and whitefly. S. cotyledon is rarely affected by pests or diseases, but over-watering or bad drainage can soon cause yellowing and deterioration, and once roots begin rotting recovery is unlikely.

SCHEFFLERA

This is a genus of small trees or shrubs with handsome evergreen foliage, originating in warm areas of the world. Some have showy flowers, usually crimson, but it is extremely rare for plants grown in pots to produce these. The species described here are very easy to raise from seed on a window-sill. S. actinophytta, the umbrella tree, bears glossy green spear-shaped leaflets from the tops of stems, umbrella fashion. In young plants, the number of leaflets is about three, but this increases to five or six, and to more in mature plants. In pots, the plant usually reaches 1.8m (6ft) after some years, depending on the size of container. Large containers will encourage much more extensive growth, but growth is very slow and a plant will remain useful in the home for a long time. Since it is happy in 10 deg C (50 deg F) minimum, it can make a very impressive plant for relatively cool places when grown to an appreciable size. Moreover, this species will do well in slight shade, although this does not imply gloom. In winter more light is preferable.

S. arboricola (syn. Heptapleurwn arbo-ricola) from South-east Asia, called green rays is very similar except that it is very much more compact and shrubby in habit. The full number of leaflets to each stem also seem to develop more quickly. It is a very deep, lustrous green, and the extra-shiny gloss is notable. It is a very striking plant set against a light background. S. digitata, from New Zealand, is also of a similar low-growing shrubby habit, and especially easy to raise from seed. The leaflets are not quite so pointed, but are toothed. This species will survive quite low temperatures if kept on the dry side during winter, and in mild areas of the country can even be grown outdoors, although a severe winter may kill it. Grown in pots it will reach about the same height as S. ac-tinophylla. In all cases plants should be retained in no larger than 20cm (5 in.) pots for as long as healthy growth is made.

Potting-on should be done in spring and the plants kept moist at all times. However. if there is risk of cool winter conditions, watering should then be adjusted accordingly. Seed germinates freely at 21 deg C (70 deg F). and the seedlings should be potted as required.

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