The gladioli , belonging to the genus Gladiolus , are a group of natural species or hybrids grown as ornamentals. They belong to the Iridaceae family, which is distributed throughout the Mediterranean basin, tropical Africa, South Africa, and Asia.
Taxonomically it is made up of more than 220 species located mostly in its center of origin in southern Africa. Furthermore, various analyzes have determined that the genera Acidanthera , Anomalesia , Homoglossum and Oenostachys are currently included within the genus Gladiolus .
Gladiolas are herbaceous plants that during the winter remain dormant in the form of a corm and thus bloom when spring arrives. The inflorescences arranged in a spike contain between 12-20 hermaphrodite tubular flowers of various colors, shapes and sizes.
At present, the production of hybrids of Gladiolus is widespread throughout the world as an ornamental plant, mainly as a cut flower. In fact, the greatest commercial importance is the hybrids that have been cultivated and improved through the crossing of various species for more than two centuries.
The corm is a thickened subterranean stem with a vertical orientation and a solid, flattened structure from which lateral buds emerge. It is covered by layers of dry leaves and formed by several nodes from which new buds are born. Its life span is one to three years.
The stem called “lathe” is made up of the underground part, the leaves and a flower spike 1-2 m high. Rigid sword-shaped leaves cover the stiff stem and support the inflorescence.
The elongated leaves, with parallel veins and lanceolate shape, are covered by a waxy cuticle. These structures are born at the base of the stem, reduced in the lower part, enveloping the stem and elongated in the upper part.
The flowers of 10-12 units and variable coloration appear in a terminal position at the end of the flower spike. Sessile and bisexual flowers are surrounded by bracts and bracteoles.
The tubular or bell-shaped perianth presents bilateral symmetry with six slightly unequal lobes. Three stamens are visible arising from the perianth tube on a trilocular and filiform-style inferior ovary.
Flowering occurs during the summer and winter. In temperate climates and under controlled nursery conditions, flowering occurs throughout the year.
The 1-1.5 cm diameter fruits are obovate or oblong capsules with three valves that are longer than wide and are dark in color. The seeds of 5-10 mm of brownish color, are compressed and with a membranous wing of light tones.
– Kingdom: Plantae.
– Division: Magnoliophyta.
– Class: Liliopsida.
– Order: Asparagales.
– Family: Iridaceae.
– Subfamily: Crocoideae.
– Tribe: Ixieae.
– Genus: Gladiolus L.
The name Gladiolus of the genus is attributed to the Roman military man and naturalist Pliny “the Elder.” It refers to the lanceolate shape of the gladiolas’ leaves, similar to the Roman sword called “gladius”.
On the other hand, during the Roman Empire, gladiolas were used as a symbol of victory. In fact, they were given to the victorious gladiators of the combats in the Roman Coliseum.
Habitat and distribution
Gladiolas are native to the Mediterranean basin and southern Africa, being cultivated since the time of the Greeks and Romans. Its greatest diversity is located in southern Africa, being found wild in Europe, North Africa and the Middle East.
Gladiolus species grow in diverse habitats, they are not demanding in terms of soil, but they require that they be loose and well drained. In addition, for their maximum floral development they need full sun exposure or long days, as well as constant humidity.
Indeed, its water requirements must be continuous, especially during the flowering phase. Also, depending on the color of their flowers, they require substantial contributions of microelements such as calcium, iron and magnesium.
Propagation by seeds
Sexual propagation by means of seeds is carried out in order to obtain new cultivars by genetic improvement or to preserve wild species. The crossing of different cultivars allows obtaining plants with a great variability of characters, including size, color, resistance or phenology.
Propagation by corms
Asexual or vegetative propagation takes place through bulblets or corms of the underground system of the gladiolus plant. The breeding bulblets are small lateral buds 2 cm in diameter that originate at the base of the original corm.
These structures are easily obtained during the fall, when the corms are harvested to preserve them during the winter. In fact, bulblets require a development of one to two years to store the energy needed to produce a new plant.
The process consists of consecutively sowing the bulblets for two years until they thicken and reach a commercial value. In this way, the corms from the same cultivar will preserve the genetic and phenotypic characteristics of the mother plant.
Gladiolas are undemanding in terms of soil quality. In general, they prefer sandy loam with enough organic matter content to provide the necessary nutrients.
Likewise, they adapt to slightly clay soils, provided they have a good drainage system, as they are susceptible to waterlogging. Usually, they require soils of medium structure, pH 6-7, good drainage, in addition to amendments of lime or organic matter.
Gladiolas require sufficient moisture in the substrate throughout their entire production process. It is especially necessary at the moment of starting flowering, when the second pair of leaves that generates the flower spike appears.
For this crop, various irrigation systems can be used, by flooding, sprinkling or dripping. For flood irrigation, the construction of seed beds is required; and drip a particular and expensive infrastructure.
For this reason, sprinkler irrigation is common in large areas, although in many cases it favors the appearance of fungal diseases. On the other hand, flood irrigation requires less investment as long as the land is level.
The commercial cultivation of gladiolas requires an always fresh soil following the irrigation chain. In fact, waterings should be applied every 2-3 days while continuing to dry the soil, especially when starting inflorescence production.
The optimal range of soil temperature oscillates between 10-20 ºC, while the ideal environmental temperature oscillates between 20-25 ºC during the day. At night temperatures between 10-15 ºC are recommended. On the other hand, at the time of formation of the flowering stem they are favorable at 12-22 ºC.
Gladiolas are susceptible to high temperatures, so environments above 30 ºC can cause alterations at the time of floral differentiation. Similarly, high soil temperatures can cause damage to the underground stems or corms.
The crop needs a relative humidity of 60-70%, in the case of humidity lower than 50% the development of gladiolas is delayed. Otherwise, excessive humidity causes excessive growth of the stems and the appearance of rots at the base of the stem.
Gladiolus species are heliophytic plants, that is, they require full sun exposure for their effective development. However, flower initiation is carried out under dark conditions, with temperature being the determining factor in this process.
The processes of flower induction and differentiation are carried out under a long day photoperiod, greater than 12 light hours. If in this phase the light is insufficient, the flowering stops. Otherwise, excessive lighting causes the flower spike to shrink.
In its growth phase it is not demanding in terms of nutritional requirements of the soil, since its needs are taken from the corm. Fertilization begins when the plant has two leaves, since the roots are susceptible to saline concentrations in the soil.
It is recommended to apply a balanced formula 2-1-2 of the macroelements nitrogen, phosphorus and potassium. Making the applications in a fractional way at the time of the appearance of the second leaf, the fourth leaf and at the time of the appearance of the flower spike.
In the case of applying fertigation, the doses should be lower in relation to direct fertilization to the soil and the cultivation phase. Initially it is recommended to apply a higher phosphorus content (1-3-0.5); in growth nitrogen (1-0.5-1) and at the time of flowering potassium (1-0-2).
The vast majority of species of the genus Gladiolus are used as ornamental flowers, grown in parks and gardens as mixed borders of attractive color. However, the main commercial object of gladiolas is the floriculture industry as cut flowers.
Geophytic and evergreen herbaceous species with simple and showy flowers that can reach up to 1.5 m in height. Native to South Africa, it is located at altitudinal levels from sea level to 1,200 meters above sea level.
This species is considered one of the ascendants of the current hybrids commercialized worldwide. In the wild it is found on wet slopes and around waterfalls in the Western Cape province.
This species is part of the group of gladiolas with the greatest distribution worldwide, being the parent species of most current hybrids. Native to southern Africa and Madagascar, it has spread through tropical Africa and the western Arabian Peninsula.
It is characterized by its long spike with five or more campanulate flowers of yellow or red tones with a yellow throat. It grows on savannas or bushes, in sandy loam soils, with a slightly acidic pH and in full sun exposure.
Known as butterfly gladiolus, it is a species that is located up to 2,400 meters above sea level on wet and flooded terrain. Native to South Africa, it is found around the Eastern Cape and Limpopo provinces.
It is an evergreen herbaceous species that measures between 0.50 and 1.20 m in height, which requires full sun exposure and a moderate amount of water. With very unusual flowers, it is a very hardy plant, cultivated as an introduced species in the United Kingdom since the 19th century.
Native to the highest mountains in South Africa, specifically the Drakensberg Mountains, it is located up to 2,750 meters above sea level. It grows in summer on rocky slopes, rough terrain, crags and dry ecosystems with certain seasonal rains. In winter it remains dormant.
Its flowers of pink or bright red hues are particular, arranged in a lopsided or downward position. The lower tepals show a red spot on a white background. They are pollinated by butterflies.
Known as night jonquil or night lily, it is a native species of South Africa, cultivated commercially on the coasts of California and Australia. It multiplies from a corm of just one or two centimeters, being widely cultivated in parks and gardens.
The plant consists of a long spike 1.5 m high with terminal flowers and three narrow leaves that wrap around the stem. The numerous aromatic flowers have six light tepals with green or purplish central lines.
Wild gladiolus plant found on rocky slopes at 600 meters above sea level in the Western Cape province of South Africa. It generally blooms in late winter and early spring with an erect spike 30-50 cm tall and red-orange campanulate flowers.
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