Ixia viridiflora

Lam.


Family:
Iridaceae (Iris Family)
Common Names:
Green Ixia, Groenkalossie (Afr.)
Red Data Listing: Vulnerable

Ixia viridiflora is one of the most striking and unusual of our winter rainfall bulbous plants and very few plants can beat it for sheer brilliance of flower.

Description
It is a winter-growing, summer-dormant, deciduous perennial. The rootstock is a corm, usually about 1 cm in diameter. It is one of the taller ixias, with upright, narrow, grass-like leaves, 400- 550 mm long. The inflorescence is a lax, many-flowered spike with 12 to 20 flowers per spike, on a slender stem, 500 - 950 mm long.A mass of Ixia viridifloraEach flower is a brilliant turquoise-green with a conspicuous purple-black circular stain or 'eye' in the middle. The dark eye is caused by the deep blue sap of the cells of the upper epidermis. The green colour is not produced by green pigment but is due to the effects of light being refracted from striations in the cell wall and granules embedded in the pale blue cell sap. The green ixia is particularly showy, a number of flowers on the spike open together and persist for several days without fading or falling off. In fact, this ixia has more flowers open together at one time on one spike than any of the other ixias. The flowers need sun and warmth to open, and are at their best on hot still days. Flowering season is late spring (October).

Ecology
Ixia viridiflora
is pollinated by hopliine scarab beetles, more commonly known as monkey beetles (Family: Scarabaeidae; subfamily: Rutelinae; tribe: Hopliini; the genera that do the pollinating include: Anisonyx, Anisochelus, Heterochelis, Khoina, Lepisia, Lepithrix, Pachycnema and Peritrichia). Beetle pollination appears to have evolved convergently in many other southern African genera, including Ornithogalum, Aristea, Sparaxis, Romulea, Spiloxene, Arctotis, Ursinia, Wahlenbergia and Drosera. Flowers that are beetle pollinated are typically salver- to shallow bowl-shaped, brightly coloured with contrasting 'beetle marks' at the bases of the petals/tepals, have no scent or odour, and produce little or no nectar. The beetles visit the flowers to eat the pollen and whatever little nectar is produced, to compete for mates and to copulate. The pollen is deposited on or between hairs on the exoskeleton and the beetles can be seen visiting one flower after another. Not all ixias are pollinated by monkey beetles. There are species with narrow tubular flowers and ample nectar that are pollinated by long-proboscid flies, and a few others with tubular flowers that produce modest amounts of nectar that are pollinated by a butterfly or by a combination of monkey beetles and short-proboscid flies, and still more species with cup-shaped nectar-producing flowers that are pollinated by bees. There is no mechanism for ballistic dispersal of the seed, the capsule dries and splits and seeds are scattered about the parent as the stem weaves and bobs in the breeze.

Distribution
Ixia viridiflora grows on the lower slopes of mountains in the Tulbagh District of Western Cape. It was also recorded in the Piketberg and Clanwilliam Districts by Marloth (1855-1931), but is no longer found there. Sadly, it is listed as Vulnerable in the Red Data Book, and is likely to be upgraded to Endangered in the near future, if the decline in numbers continues.

The genus Ixia consists of about fifty species and belongs in the Iris family. Ixia is endemic to the western and southern parts of South Africa and its distribution matches almost perfectly with the winter-rainfall region: from Namaqualand in the north west, through to the Cape Peninsula, inland into the Karoo, and eastwards to the southern parts of Eastern Cape. The highest concentration of species occurs in the countryside around Caledon, Wellington, Paarl, Stellenbosch, Tulbagh, Malmesbury, Piketberg and Clanwilliam. Ixias are exclusively winter-growing, summer-dormant plants.

Name
There are two opinions on the derivation of the genus name. The one says that it is from the Greek ixos meaning mistletoe (viscum), birdlime, referring to the viscous sap (Jackson); the other says that Linnaeus derived the name from an old Greek name for a plant noted for the variability of its flower colour (Lewis 1962). Since Ixia is a variable genus of many flower colours, the latter explanation is more appropriate. In fact, in the late 1700's when the genus was first established and new plants were being discovered in South Africa with specimens shipped to Europe, many species that are today not considered part of the genus were described in the genus Ixia, thus making it appear even more variable to the botanists of the day than it actually is. The species name viridiflora means green-flowered in Latin.

The common name green ixia or 'groenkalossie' in Afrikaans is also derived from the green colour of the flowers. The name 'kalossie' is a general name given to many species of Ixia and Lachenalia. It is differentiated by a prefix denoting a distinguishing characteristic of the plant e.g. the colour of the flower or habitat of the plant i.e. 'groenkalossie' if the flowers are green, 'klipkalossie' if the plant grows in a rocky habitat, etc. The word 'kalossie' is derived from the Afrikaans 'kalotjie' (Eng.: calotte), a skull cap; the bowl-shaped perianth of some of the ixias is reminiscent of the shape of an old fashioned skull cap. Ixia viridiflora has also been called the amethyst ixia, and the green-stained ixia, although Lewis (1962) thinks that the plant illustrated by Curtis and called the amethyst ixia is actually a hybrid with Ixia viridiflora as one of the parents. Some other species in the genus e.g. I. flexuosa and I. polystachya are called 'koringblommetjie' or cornflower as they are frequently found growing in wheat lands in the Cape. Other completely unrelated plants also share this common name, e.g. Scabiosa africana and Lapeirousia corymbosa. In the USA and Australia, ixias are also known as wand flowers or African cornflowers or corn lilies.

Growing Ixia viridiflora

Growing in a pot at KirstenboschIxias have been cultivated in Europe since the mid 1700's. They hybridize quite readily, and today, Ixia hybrids are freely available and grown all over the world. Getting material of the true species is a bit more difficult and growing them is more challenging. Ixia viridiflora although quick to flower from seed, is not the easiest of the ixias to grow, as it is quick to rot in poorly drained soil. The basic requirements for growing this ixia are: sandy soil with good drainage, a sunny location, and a completely dry, dormant period in summer.

Ixia viridiflora makes an excellent pot plant but is not well suited to a permanent position in the garden, even in winter rainfall areas. They are susceptible to fungal diseases, are eaten by mole rats and porcupines, and need a completely dry summer. To deal with this problem, one can plunge pots of Ixia viridiflora into the garden during the growing and/or flowering period and remove them during the summer dormant period.

Corms should be planted in autumn (April-May) while still dormant. You will need a pot at least 30 cm in diameter. Place a layer of stone chips over the drainage holes and fill three quarters of the pot with a freely-draining soil mix, e.g. equal parts coarse river sand and fine compost (leaf mould). Plant the corms in a 1 cm layer of pure river sand and cover with a 1 cm layer of the soil mix. Water thoroughly immediately after planting and place in a spot that gets at least half-day sun. Once growth becomes visible, a good drenching every ten days is recommended. Because Ixia viridiflora is tall, it may need to be staked if your garden is windy. Inorganic fertilizers should be avoided, particularly high nitrogen fertilizers, but organic fertilizers can be used sparingly. When the leaves begin to dry, stop watering altogether. The corms can be left in the pot, provided it is stored in a cool, dry spot. It is advisable to lift them every second year. This gives you the opportunity to clean them, inspect them for disease and discard the badly damaged ones.

Although Ixia viridiflora corms do multiply by producing offsets, the corms are relatively short-lived and constantly need to be re-propagated from seed. Seed should be sown in autumn (April-May) in a sunny spot, in well-drained medium at a depth of 3-5 mm. Sow thinly and allow good ventilation, otherwise damping off may occur. It is best to use a seed tray that is at least 10 cm deep, or raised seedbeds. Keep the soil moist and germination should occur in three to four weeks. Ixia viridiflora is a rapid grower, and can produce its first flowers only seven months after germinating although most seedlings will flower in their second season. It is best to leave the seedlings undisturbed until after their second season.

Ixias in containers are susceptible to mealy bug infestation of the corms. This is eventually fatal and should be treated with a drench of chlorpyrifos. Likewise, during storage, it is best to dust them with bexadust to keep the mealy bugs off. The foliage and developing flower buds can also be attacked by aphids and red-spider mite, but seldom severely enough to require an insecticide. The corms are susceptible to attack by fungi causing rotting and can be dusted with fungicides like 50:50 captab:iprodione prior to planting.

References

  • DUNCAN, G. 1999. Ixias for pot and garden. Veld & Flora 85: 78, 79.
  • LEWIS, G.J. 1931. Ixia. Journal of the Botanical Society of South Africa 17: 13-16.
  • LEWIS, G.J. 1962. South African Iridaceae, the genus Ixia. Journal of South African Botany 28: 45-195.
  • GOLDBLATT, P., BERNHARDT, P. & MANNING, J.C. 2000. Adaptive radiation of pollination mechanisms in Ixia (Iridaceae: Crocoideae). Annals of the Missouri Botanical Garden 87: 564-777.
  • GOLDBLATT, P., BERNHARDT, P. & MANNING, J.C. 1998. Pollination of petaloid geophytes by monkey beetles (Scarabaeidae: Rutelinae: Hopliini) in southern Africa. Annals of the Missouri Botanical Garden 85: 215-230.
  • SMITH, C.A. 1966. Common names of South African plants. Memoirs of the Botanical Survey of South Africa No. 35. Government Printer, Pretoria.
  • JACKSON, W.P.U. 1990. Origins and meanings of names of South African plant genera. University of Cape Town.
  • HILTON-TAYLOR, C. 1996. Red Data List of southern African plants. Strelitzia 4. National Botanical Institute, Pretoria.
  • CURTIS, W 1804. Curtis's Botanical Magazine.Series 1. Vol. 21 plate 789.

Author: Alice Notten
Kirstenbosch National Botanical Garden
October 2002

 


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