Colocasia Black Magic

Amongst the largest leaves in my garden belong to the genera Colocasia plants, which are sometimes referred to as 'elephant's ears'. The resemblance is rather remarkable and these imposing foliage plants can really make a statement in a garden.

This plant belong to the broad plant family known as the Araceae, the members of which are sometimes known as aroids. Many of these plants come from tropical climates and were traditionally used as houseplants. However, in Sydney we can grow many of them outdoors as permanent plantings, or in pots. On the whole, they are best suited to shadier parts of the garden, with sufficient moisture: many can actually grow well in ponds. They can introduce an element of bold contrast with their distinctive leaves and flowers, and mix in well with other warm-climate plants that grow well in our climate, creating the ambience of a tropical rain forest.

Flower of Spathiphyllum species

Flower of Spathiphyllum species

The sculptural flower of aroid plants is usually a cylindrical spadix, surrounded by an enclosing leaf-like spathe; in some instances the flowers have a horrible smell, on order to attract insects for pollination. The dead-white arum or calla lily (Zantedeschia aethiopica) is a classic example of the floral form of the family; there are now coloured hybrid Zantedeschia around, such as orange, yellow and pink, though the original white remains the easiest to grow. Other decoratively flowered forms include the various Anthurium species and cultivars (ht 60 cm), the spathes of which come in various colours, including white, pink and red, appearing to be almost made of plastic. The peace lily, Spathiphyllum (ht 30 cm), is similar, with lovely white flowers (turning green with age) almost all year round, which are very pretty in a shaded garden bed with silvery-leaved plants - I find it easier to grow than the Anthurium, which are probably at the edge of their comfort zone in some Sydney suburbs. There is a giant form of Spathiphyllum, called 'Sensation', which is very effective.

Syngonium

Syngonium

There is a huge variety of foliage forms in the aroid family, ranging from the curious three-leaved Pinellia ternata (ht 30 cm), the often highly patterned and coloured, arrowhead-shape-leafed Caladium bicolor (ht 60 cm; alas, they generally don't survive through winter in Sydney's climate) and similar Syngonium (ht 30-50 cm), glossy Thaumatophyllum xanadu (previously known as Philodendron 'Xanadu', ht 75 cm), the extraordinary perforated 'Swiss cheese' leaves of Monstera deliciosa to the dramatic Alocasia and Colocasia specimens. Some of the aroids have aerial roots, which allow the plants to climb up trees: Monstera, somePhilodendron and some Syngonium have this feature. They can change their personalities when they do this and become rather fearsome so I would avoid letting them anywhere near a tree! I do use Syngonium as a groundcover in difficult dry areas where little else will grow. There are some interesting Syngonium leaf colours available these days, including gold, silver and pink, and some miniature-leaved ones that don't spread anywhere near as much as the original species.

Alocasia macrorrhiza (centre)

Alocasia macrorrhiza (centre)

The classic 'elephant's ear' is the glossy green Alocasia macrorrhiza (ht 1 m), but I find the velvety leaves of Colocasia esculenta cultivar 'Black Magic' (ht 60-100 cm) the closest to the real thing in terms of colour - and less inclined to take over! Mine have grown to become enormous this past summer, perhaps because of all the rain we have had over the past few months. It can die back a bit in winter and is certainly not at its best at that time, though in general Alocasia macrorrhiza doesn't seem to mind our winter months and always looks presentable. There are some unusual variegated forms of Alocasia sometimes available, including ones with dramatic silver veins or dark markings on the foliage - though these may be more sensitive to cold than the basic species. The big broad leaves of Alocasia and Colocasia provide a very satisfying contrast to ferny, strappy or grass-like foliage in the garden. Their flowers are not very showy.

Lime form of Xanthosoma sagittifolium in the former garden of Sandra Wilson, Sydney

Lime form of Xanthosoma sagittifolium in the former garden of Sandra Wilson, Sydney

A similar plant is Xanthosoma sagittifolium (ht 80 cm -1 m) and a particularly lovely cultivar has vibrant lime-green leaves, which really light up a dark spot in the garden. It is probably cold sensitive and should be protected in winter even in Sydney - growing it in a pot allows it to be moved under shelter in the colder months. Some aroids have edible yam-like tubers and others, such as Monstera deliciosa, have flavoursome fruit. Many others are toxic, though, so please don't sample them indiscriminately!

These plants are a world away from the sorts of plants I used to grow in my traditional English-style cottage garden, but I am finding them more and more exciting as time goes on, and much easier to cultivate in the garden. Their strong form provides a much-needed contrast in what can be a sea of amorphous foliage.

Blog first posted 21 March 2010; updated 19 March 2023.