Zantedeschia elliottiana: Calla Lily
The calla lily was a traditional part of bridal bouquets in our grandmother’s day and at one time it was also a very popular house plant. Times change, however, and with the increasing number of centrally-heated homes the originally cultivated species Zantedeschia aethiopica has been relegated to the sidelines. Offered in its stead are other, far lovelier thermophilous species with a spathe that is not white but brigthly coloured. It is almost impossible to understand why they are so slow to be adopted in cultivation when they are such extraordinarily attractive plants. As a rule they are not even to be found in large botanical gardens and are apparently waiting to be brought by interested persons from their native habitats in tropical and South Africa.
A common species, encountered in collections belonging to experienced amateurs and grown for the cut flower trade, is the Zantedeschia elliottiana (syn. Calla elliottiana) from the highlands of south-east Africa. It grows from a large, or rather a shortened tuberous rhizome. The leaves are long-stalked, shortly oval, heart-shaped, with numerous white, transparent ‘windows’. The spathe is about 15 cm (6 in) long and coloured deep yellow; it is not brown at the base.
Several beautiful cultivars have been raised in the United States of America, derived chiefly from this species with large brightly-coloured. Also found in culture are bright pink cultivars, derived apparently from T. rehmannii, which has a violet-purple spathe.
Unlike the traditionally grown cool-loving species, Z. elliottiana as well as other variously-coloured cultivars and thermophilous species are suitable for modern centrally-heated homes. Their tubers require absolutely dry conditions in winter and temperatures of up to 30°C (86°F); the pots may be put on top of a radiator. This, seemingly drastic, procedure is necessary if the plants are to flower. In spring the tubers should be transferred to a fresh potting mixture composed of peat, sand and loam, and watering should be resumed; water as well as feed should be applied liberally throughout the growing season. The greatest enemies are mites and white flies, which are readily ‘attracted’ to the plants, and so it is necessary to spray them with an insecticide now and then.