With a genus as complex and variable as Gladiolus, one finds that there are more then one useful ways to sort the many species. This page links to several indices sorted by growth cycle or color, offering a more horticultural grip on the genus.
In addition to those, here is a list of species without images. If you can help to keep this short, please contribute!
Growth cycle indices
The division in summer- and winter rain species is mostly viable for the South African species, as the Eurasian gladiolus have their own pattern, with winters often too cold to grow, and a (late) summer dormancy that may or may not dependent on water supply.
Summer rain Gladiolus are mostly from the eastern part of South Africa. They generally like their summers wet and their winters dry, but just exactly how wet and how dry may vary widely depending on on the exact location of origin. Among the summer rain species are some of the most frost hardy of the African species, but as most tropical African Gladiolus follow a summer rain pattern as well, some are quite frost tender. Many ancestors of the common garden hybrid Gladiolus can be found in this group, most noteworthy Gladiolus dalenii, Gladiolus oppositiflorus and Gladiolus papilio.
Summer Rain Index
Winter rain Gladiolus like their winters wet and mild and may need a dry summer dormancy. They are often less hardy, reaching down to USDA zone 8 at most. Out of this group, Gladiolus cardinalis and Gladiolus tristis added their features to the garden hybrids.
Winter Rain Index
Color indices
Gladiolus species offer nearly any color besides a clear dark cornflower blue. Of course, color is a rather subjective perception, and some species are quite variable, so several species can be found in more then one index.
Red and orange Gladiolus: Several species settle for this clear signal colors, often associated with bird pollination. This may result in very special flower shapes with long perianth tubes.
Red and orange Gladiolus
Yellow Gladiolus. Yellow may not be the first color that comes in mind thinking of Gladiolus, but there are some very striking species in this category. Quite often, there is a secondary yellow form of mainly orange or purple Gladiolus species.
Yellow Gladiolus
Pink and mauve Gladiolus: From pale rose and mauve to salmon to screaming pink, this color complex offers many shades and the widest range of species in the color indices.
Pink and Mauve Gladiolus
Purple Gladiolus: Magenta to dark bluish purple is a another focus of Gladiolus diversity. Most of the Eurasian forms can be found here, but there are many South Africans as well.
Purple Gladiolus
Blue Gladiolus: Clear blue is rare among Gladiolus, but a few species still show variations in mostly pale tones.
Blue Gladiolus
White and cream Gladiolus: These are often associated with moth pollination, and so some of the most fragrant Gladiolus can be found in this category.
White and cream Gladiolus (including white forms), white and cream Gladiolus (white only species)
Patterned Gladiolus: Most Gladiolus sport a few lines and spots on their flowers, but there are some so heavily patterned that the base color becomes obscured.
Patterned Gladiolus
Green and off-colored Gladiolus: Often not considered a classical beauty, these offer their very own charms. Once again, this category contains some species with unusual side-forms
Greenish Gladiolus