Alpine Garden Society

Ulster Group

Plant of the Month, November 2011
Gladiolus oppositiflorus - by David Ledsham
Gladiolus oppositiflorus, also known as the Transkei Gladiolus, is just one of an extensive number of Gladiolus species to be found in Sub-Saharan Africa, particularly in regions south of the Tropic of Capricorn. In fact this part of the world is considered to be the main centre of distribution for the genus with more than 160 species listed, many of them endemics which occupy very restricted ranges. This inevitably means that many species are currently threatened by road building, overgrazing and holiday development.  
 In the early twentieth century Gladiolus oppositifolius made its contribution to the genetics of today's hybrid cultivars but it has to be said that almost all the original wild species are very garden worthy in their own right. Just like orchids, the flowers of many gladioli are adapted to a particular strategy of pollination possibly involving a moth, a bee, or a sunbird so that consequently, just as with orchids, this specialisation has resulted in a spellbinding array of floral pattern, colour, and form. 
The gladiolus featured here is an endemic species occurring on the Transkei Wild Coast which is in the summer rainfall region of the Eastern Cape where it is to be found growing in open grassland and along streams.
 I have grown G.oppositiflorus for a number of years on damp but well drained banks which receive the greatest amounts of sunshine. The leaves predictably appear in mid-September, and by early October the plants are in full flower. The seed I initially used was from Silverhill Seeds and was referable to the subspecies 'salmoneus' but I've noticed that the flower colour of respective plants can vary from a deep pink to a quite silvery pink and I understand that the subspecific rank may no longer be valid.  
 My plants rarely set seed, possibly because of the scarcity of sunbirds in Northern Ireland and my attempts to grow other wild species have not always been successful, however I notice that at least two U.K. nurseries are now offering corms of a number of the rarer species and maybe this range will increase as this beautiful genus becomes popular.


The Color Encyclopedia of Cape Bulbs,    Manning,Goldblatt,and Snijman :    Timber Press 2002

The Iris Family : Natural History and Classification, Goldblatt & Manning : Timber Press 2008