The popular garden and horticultural specimen Calla Lily or Arum Lily are in the genus Zantedeschia, which originated in southern Africa. It is neither a lily nor a calla nor an arum. Nor is it a true flower; rather, what we know as “Calla Lillies” are an inflorescense of tiny flowers surrounded by a petal-like spathe.
Many Calla Lillies have a long flowering season. The new blooms of the popular Zantedeschia aethiopica are faintly scented with a light, slightly sweet, buttery fragrance. The odour becomes less sweet as the flower ages. The central spike, termed the spadix, is an inflorescence that has both female (lower) and male (upper) flowers that spiral up from the bottom. The flowers are usually obscured by the spathe that surrounds the spadix. The dying spathe reveals the fruit which is also of horticultural interest. Calla Lillies with shorter flowering seasons are also grown as ornamental plants due to their lush foliage; of particular note is Zantedeschia elliottiana, with deep green leaves with white spots.
Zantedeschia are hardy, insect-attracting plants with few natural pests. As a result, they are a delight for novice gardeners, but in warm climates they can become a pest. Zantedeschia have naturalised in some areas and are classed as weeds in parts of Western Australia. According to a New South Wales government fact sheet, the species can be invasive and "All Zantedeschia species are highly poisonous when eaten raw." 
In popular culture
Actress Katherine Hepburn immortalized the Calla Lilly in a line from the feature film Stage Door, "The Calla Lillies are in bloom again." Their pure white colour has made them a popular choice for bridal bouquets.
- Arum or calla lily (Zantedeschia aethiopica ) hosted by www.esc.nsw.gov.au and sourced 26 November 2007