Gladiolus are found in a variety of types that include both the species and hybrid glads. The different types of species represent the geographic and ecological range of the many species in this genus. The different combinations of species used to create the different hybrids has led to the establishment of several different types of hybrids as well.
Winter Blooming Species
and Hybrids
The Cape region of South Africa is home to over 100 different species of Gladiolus. Most of the Cape species grow and bloom in the winter, which in this region of South Africa is mild, and similar to that of Southern California. Many of the species are reasonably hardy and will tolerate some frost. Unlike the more familiar grandiflora hybrids, these species are small plants, typically they produce one or just a few slender leaves before flowering. The flowers are small and bourne on slender stalks. Many of the species, such as Gladiolus tristis, pictured on the right, are strongly fragrant. Hybridizers in the late 19th and early 20th centuries produced many hybrids with these species. Virtually all gladiolus species are diploids with 30 chromosomes and are interfertile. Most of these hybrids are long gone, however more recent hybrids have been produced including the so-called Homoglads; a cross between Homoglossum watsonius (recently reclassified as Gladiolus watsonius) and Gladiolus tristis. Based on descriptions of some of these older hybrids, there is great potential for producing useful garden plants from these species.
- An excellent reference for Gladiolus species native to South Africa is:
Gladiolus in Southern Africa
by Peter Goldblatt and John Manning
Fernwood Press, Vlaeberg, S.A., c 1998
- Information for some of the Cape species and details of the origin of modern glads can be found in:
Growing Gladioli
by Eric Anderton and Ron Parks
Timber Press, Portland, OR, c 1989
- Cultural information on Gladiolus species and many other genera of cape bulbs can be found in:
Cape Bulbs
by Richard L.Doutt
Timber Press, Portland, OR, c 1994
I have also put together a page with my cultural techniques and observations. Winter flowering species cultural notes. Obtaining bulbs is something of a challenge in the US. There are a few growers of specialty bulbs that carry some species. Specialty seed companies and the International Bulb Society are sources for seeds. All of my current stock has come from Jim Duggan's Flower Nursery, 1452 Santa Fe Dr., Encinitas, CA 92024. (760) 943-1658, www.thebulbman.com. His stock is high quality and the bulbs have consistently bloomed the first year. His web site has an extensive collection of pictures of many different South African bulbs.
Summer Blooming Species
In
addition to the concentration of winter blooming species in the
Cape region, many more species are found in the inland areas
of South Africa and tropical Africa. Several species are even
native to Europe. One of these summer-blooming African species,
Gladiolus dalenii, is chiefly responsible for the production
of the summer blooming hybrids. G. dalenii occurs over a large
region in Southern Africa and has many distinct geographic forms,
which in the past were given many different species names, including
G. primulinus, a form that was very important in the production
of miniature Gladiolus hybrids. Several other summer blooming
species also figure in the development of the modern hybrids,
including G. cruentus, G. oppositiflorus, G.
papilio and G. saundersii. Many other species were
grown at the time the early hybrids that lead to modern Gladiolus
hybrids, but it is not clear what other species contributed to
the modern germplasm. The genes of G. papilio are clearly
present in modern glads as evidence by the blotched varieties.
Either or both G. cruentes and G. saundersii contributed
the red color found in many modern cultivars. For the most part
these species are not readily available. However, several of
the European species can be found in bulb catalogs. One species,
Gladiolus muriale (formerly Acidanthera bicolor var
Muriale) is commonly found in catalogs and garden centers,
often under the name "peacock lily". G. muriale,
which is pictured at left, is strongly scented and blooms very
late in the summer, often just before frost in Northern areas.
It has been used to develop several hybrids with modern Gladiolus,
the best known is 'Lucky Star'. Unfortunately the fragrance in
the hybrids is not as strong as in the species, and is readily
lost in further crosses to the grandiflora type hybrids, and
in fact 'Lucky Star' was the only fragrant seedling produced
from a large number of crosses made by Mrs. Joan Wright in the
1950's between G. muriale and modern hybrids
- A useful reference for the summer flowering species:
Gladiolus in Tropical Africa
by Peter Goldblatt
Timber Press, Portland, OR, c 1996
Nanus hybrids
The nanus group of hybrids is commonly found in catalogs and garden centers labeled as "Butterfly Glads" or "Winter-hardy Glads". Both of these names fit this group well. For a group of hybrids derived from African species, they are surprisingly hardy (to USDA zone 4 when overwintered in the ground and can also be treated like the Grandiflora hybrids and dug each fall and replanted in the spring). Many of the hybrids found today were bred at the turn of the century, which is a testament to the disease resistance of this group. Although the exact parentage of these hybrids is mostly lost, we know that they are the result of crossing the summer and winter blooming species together. In fact, virtually all of them are actually first generation hybrids. We know this because they are sterile, with three sets of chromosomes (triploid) instead of the normal two sets (diploid) or the four sets found in the modern Grandiflora hybrids. Because odd sets of chromosomes cannot pair during the first division of meiosis, normal gamets cannot be formed. However, in gladiolus hybrids, it has been found that triploids do produce some gamets and that these typically have either 15, 30 or 45 chromosomes. These viable gametes typically form in the ovaries and thus the plants are pollen sterile. If the triploid plants are pollinated by pollen from a diploid (15n) or tetraploid (30n), some of the resulting seeds will be fertile tetraploids (2n=60). The fact that most nanus glads are triploids indicates that they derive from crosses with G. dalenii, a Summer blooming species with four sets of chromosomes (tetraploid), and some of the many Winter blooming, diploid species.
The nanus glads display a variety of colors and patterns, but most have conspicuous darts of color on the upper petals. This is in contrast to the blotch pattern in the modern Summer blooming glad hybrids, which is on the lower petals. However, this pattern of darts is very similar to that seen in G. carneus. The nanus glads come in white, pink, salmon and some varieties are nearly red. They have graceful spikes with fewer than 12 buds. Because of their grace and hardiness they are useful garden subjects, and are grown as cutfloers in Europe. Recently, breeders in Israel have produced a new series of hybrids by crossing modern Summer flowering hybrids with the Winter blooming species G. tristis. These have been produced for the cutflower trade and should be similar in growth habit and bloom season to the nanus cultivars.
Modern Summer blooming
hybrids
The modern Summer blooming hybrids are very different from
the species glads. The modern hybrids or "Grandiflora"
hybrids are much larger, both in terms of flower size and thesize
of the flower spike. Some modern hybrids can have up to 40 flower
buds and can hold ten or more 5 1/2" wide flowers open at
once. Hydrids such as Alpine Sunset (shown on the right) have
been bred for exhibition at the
many gladiolus shows around the country. Many other hybrids have
been bred for commericial trade. While typically not capable
of producing the individual spikes that the exhibition varieties
can, the commercial varieties can be cut in tight bud and open
days later in water. These spikes can bloom for more than a week
with proper treatment. The ease of handling and the brilliant
colors make gladioli one of the premier cutflowers.
In addition to the larger size,
modern hybrid glads have flowers in colors and forms not found
in the species. Most modern glads have at least some ruffling
of the petals and some varieties are so heavily ruffled and textured
that they almost appear to be carved from wax. The hybrid glads
can be found in virtually all colors from pure white to nearly
jet black. Pink and salmon colored varieties are perhaps the
most common, but rich reds, golden yellows, purples and browns
are also found among the modern cultivars. Even green, blue and
violet glads exist. Although these three colors are not "true"
colors in glads, modern hybridizers have come a long way towards
producing glads that really look green and blue. Part of the
reason for the many colors and forms that modern glads take is
in the number and kinds of species used to create them.
Although the vast majority of
Gladiolus species are diploids with 30 chromosomes, the Grandiflora
hybrids are all tetraploids with 60 chromosomes. The tetraploid
nature of modern garden glads traces to the prominence of G.
dalenii in the parentage of the modern hybrids. Unlike most
other species, G. dalenii is a tetraploid with 60 chromosomes.
G. dalenii occurs in a large number of different forms,
and has a wide natural range. It is found in the interior of
South Africa, and ranges north to central Africa. Because of its
wide range
and variability its many forms were originally described as separate
species (G. psittacinus, G. dracocephalus, and
G. natalensis from South Africa; G. primulinus and
G.quartinianus from Tropical East Africa).
Crosses between the diploid summer and winter blooming
species and forms of G. dalenii resulted in many different
hybrids. Although most of these hybrids were triploids and thus
mostly sterile, in gladioli, triploids produce unreduced gametes
at a high frequency. Because of this property, pollination of
the triploids by diploid species results in a reasonable frequency
of fertile tetraploid offspring. By this route, hybridizers at
the turn of the century incorporated several other summer and
winter blooming species, (including G. cardinalis,
G. cruentes, G. oppositiflorus, G. papilio, and
G. saundersii) leading to the creation of the modern
Grandiflora hybrids.
Virtually all of these species were incorporated into the germplasm by the 1920's and virtually all of the improvement since that time has been produced by intercrossing hybrid varieties. In the 1940's, 50's and 60's gladioli reached the height of their diversity. Semi-double and fully double forms were bred along with lacinated forms and varieties with huge florets. Most of these varieties are now gone, however, the germplasm of today's gladioli certainly contains the capacity to reproduce these forms.
Even though today's
varieties are not as diverse in form, hybridizers have greatly
improved the degree of ruffling of the flowers and have continued
to improve the number of buds produced per spike. Although many of the
novelties of the past have disappeared, new variants such as the
variety "Candy Cane" pictured here have been developed recently.
Fragrant summer hybrids have been the subject of several modern
hybridizer's efforts, but a strongly fragrant summer flowered
hybrid with remains elusive.
The latest hybrids are unsurpassed in ruffling and color. In addition, the smaller flowered varieties have been highly developed, to the point that they rival the larger flowered varieties in form and style. Although most gladiolus varieties face forward, upward facing varieties, face-ups, have been developed. These varieties have long been known, but they have achieved something of a revival recently with ruffled varieties in new colors.