Hi Véronique,
There's more than 150 species of Gladiolus in South-Africa and they have nearly all the same shape of leaves... Before blooming, it seems very difficult to be able to identify or compare two specimens. You know that I also grow some gladiolus from south-Africa (only 15) and I won't try to identifiy what I have before seeing their flower. I know that it can be frustrating not to be sure of what your are growing, specially when this is a much wanted species or when it doesn't behave as it should : I have some Gladiolus scabridus that are now starting to grow as a winter species while it is said to be summer grower... Young plants are sometimes a bit disappointing and disappointed by our growing conditions...