Sparaxis elegans

(Sweet) Goldblatt

Family : Iridaceae
Common names : Cape buttercup, spar axis, pale harlequin flower. (Eng.), spogfluweeltjie (Afr.)

Sparaxis elegans

Sparaxis elegans is, as its name suggests, one of the most elegant and aesthetically pleasing species the Greater Cape Floristic Region (GCFR) has to offer any plant enthusiast. Its most striking features are the colourful patterning and curious way the anthers seem to coil and twist around the style.

Curling anthers

Description
Sparaxis elegans is a geophytic perennial plant reaching heights of 100–300 mm. It has a rounded corm as its main underground rootstock, measuring 10–17 mm ( Goldblatt 1992; Goldblatt & Manning 2013 ) in diameter, with a fine fibrous outer coating. Stems are simple or in some cases branching from the base. Five to nine lance-like leaves with tapering tips are arranged in a basal fan, where the leaves reach to about half the length of the stem. The stems bear 3–5 symmetrical flowers, which are arranged along the tips of the stem; an inflorescence known as a spike (Goldblatt & Manning 2013).

The flowers of Sparaxis elegans are predominantly salmon-pink or white, although other colour variants can be found in areas of co-occurrence. Flowers are purple in the centre and have a ring of distinctive yellow and black markings surrounding the throat of its short funnel-shaped tube (Arkive internet reference; Goldblatt & Manning 2013 ). They also lack any perceivable scent. The male reproductive parts (or stamens) are very distinct for this species: the purple filaments display anthers that are S-shaped and tightly curled around the style. This morphological feature is not seen in any other member of the genus.

According to Goldblatt and Manning (2013), the end of the flowering period, which ranges from August to September, yields somewhat ‘unremarkable' fruits. Fruits are cartilaginous and split soon after drying to release spherical seeds that flaunt a glossy-red colour.

Conservation status
Sparaxis elegans is classified as Vulnerable in the South African Red List. The greatest known threats to the species include overgrazing by livestock and the loss and alteration of its habitat due to agricultural disturbances. Populations of S. elegans naturally occur on nutrient-rich clay soil, which is the most productive agricultural land on the Bokkeveld Plateau, resulting in 77% of its habitat already being lost. Currently, the remaining populations occupy an area of 16 km 2 from north of Nieuwoudtville southward to the Klein Kobee (Goldblatt & Manning 2013). Most of the habitat loss occurred over the last 70 years (mostly in the 1950s) and population trends appear to be stable for the time being. However, ploughing of natural vegetation for more crop fields still occurs and habitat loss remains a potential threat. Conservation initiatives, such as alien invasive clearing (to encourage regeneration of natural vegetation), is underway in this species' area of occurrence and may indirectly assist in the persistence of the species. Furthermore, one population of Sparaxis elegans is situated in a protected wildflower reserve in Nieuwoudtville.

Distribution and habitat
Sparaxis elegans is endemic to the GCFR of the Western Cape, occurring from the Bokkeveld Plateau in the northwest, extending southwards for approximately 25 km into the Nieuwoudtville area. The species is restricted to winter rainfall regions of South Africa and generally grow in light to heavy clay soils ( Goldblatt 1992 ). The more common salmon-pink form occurs in the north of its range in the Nieuwoudtville area, and the white-flowered form occurs to the south, sometimes in pure stands, or mixed with the pink form (Goldblatt 1992).

Derivation of name and historical aspects
The genus name is derived from the Greek sparasso (meaning ‘to tear'), pertaining to the lacerated bracts that surround the flowers. The species name is derived from the Latin elegans, which most likely pertains to the graceful and elegant colouration and patterning of the tepals.

The genus Sparaxis has been introduced and cultivated in Europe since the 1780s (Du Plessis & Duncan 1989; Goldblatt & Manning 2013). The genus belongs to the Iridaceae family and was described by Ker Gawler in 1802. It now includes species previously referred to as Streptanthera and Synnotia, resulting in a genus with 16 species (Goldblatt & Manning 2013). Sparaxis is believed to be monophyletic (i.e. all species originate from a single common ancestor) and largely defined by vegetative features, including leaf and floral bract morphology.

Insect on flower

Ecology
For a genus composed of only 16 species, the pollination systems within Sparaxis are unusually diverse (Goldblatt et al. 2000). Goldblatt and Manning (2013) suggests hopliine beetle ( Peritrichia rufotibialis ) pollination for S. elegans, although the tabanid fly, Philoliche atricornis, frequently visits the species, possibly in search of minute traces of nectar. Due to the exploitation of two different – but equally effective – pollinator groups, this species is regarded as having a bimodal pollination system.

Pollen is typically coloured yellow to white in Sparaxis but S. elegans is the only species that produces dark purple to brown pollen. Goldblatt and Manning (2013) suggest this is a way to camouflage pollen from pollen-collecting insects.

Sparaxis elegans is a self-compatibility species: they are able to produce seeds via self-pollination when conditions for cross-pollination are not met. Sparaxis species are interfertile and hybrids between S. elegans and S. grandiflora have been produced.

Uses and cultural aspects
Sparaxis elegans is best valued as a garden and indoor ornamental (Heywood 1978) and has been used in horticulture for over 200 years (Goldblatt & Manning 2013). They are excellent for containers and make great, long-lasting cut flowers. Bryan (1989) states that Sparaxis species have not ‘enjoyed the popularity they deserve' and their various colour combinations demands they be more widely grown. Apart from horticultural value, Sparaxis, in general, has not been used for any commercial purpose.

sparaxis elegans

Growing Sparaxis elegans

Sparaxis elegans plants prefer full sun and well-drained loam soils, although they do well in a range of different soil types. Plant corms in spring, about 50 mm deep and 70–100 mm apart. Grow them in bold groups of 25 individuals or more, in order to experience the full effect of the radiant colours.

Pots
This species also makes an excellent container subject and are displayed to great advantage in rock garden pockets that are kept dry in summer. Plants are sensitive to frost and should not be grown in pots when temperatures drop below 0°C for extended periods. Water seedlings well, but after flowering, soils must be left to dry completely to allow corms to ripen. Corms can stay in soils for long periods but in containers overcrowding of the rootstock may occur and separation is necessary (Bryan 1989).

Propagation
Separating cormlets from parent corms is a great way to increase the stock. It is easy to germinate seeds providing seeds are sown in autumn. Some seedlings will flower after one year but all will be of flowering size in the second season. When growing plants in containers, use a light sandy soil mix. Keep soils moist and well watered as soon as germination has taken place. Grow seedling until the foliage dies down, upon which corms can be remove from the soil and cormlets separated by size. Those that are large enough can be re-planted to flower and the remainder are replanted in rows for another growing season (Bryan 1989).

Pests and disease
These plants are hardy and seldom attacked by any pests or diseases (Bryan 1989), although slugs and snails do relish the foliage, and porcupines are known to eat the corms (Duncan 2000).The most likely problems that may occur are those caused by too much water in summer; the corms are subject to fungal rotting if not kept dry (Duncan 2000).

References and further reading

  • Arkive : http://www.arkive.org/cape-buttercup/sparaxis-elegans/image-G58601.html. Accessed May 2014
  • Bryan, J.E. 1989. Bulbs: Volume II, I-Z. Timber Press, Portland.
  • Duncan, G. 2000. Grow bulbs: A guide to the cultivation and propagation of the bulbs of South Africa and neighbouring countries. South African National Biodiversity Institute, Cape Town.
  • Du Plessis, N., & Duncan, G. 1989. Bulbous plants of southern Africa: A guide to their cultivation and propagation . Tafelberg, Cape Town .
  • Goldblatt, P., Manning, J.C. & Bernhardt, P. 2000. Adaptive radiation of pollination mechanisms in Sparaxis (Iridaceae: Ixioideae). Adansonia 22: 59–70.
  • Goldblatt, P. & Manning, J. 2013. Systematics and biology of the Cape genus Sparaxis (Iridaceae). Strelitzia 32. South African National Biodiversity Institute, Pretoria.
  • oldblatt, P. 1992. Phylogenetic Analysis of the South African Genus Sparaxis (Including Synnotia) (Iridaceae-Ixioideae), with Two New Species and a Review of the Genus. Annals of the Missouri Botanical Garden , 79: 143-159
  • Heywood, V.H. 1978. Flowering plants of the world. Oxford University Press, London.
  • Kesting, D. & Clarke, H. 2001. Botanical names: What they mean. Ink and Print, Port Elizabeth.
  • South African National Biodiversity Institute (SANBI): http://redlist.sanbi.org/genus.php?genus=1536 . Accessed May 2014.

 

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With thanks to Eugene Marinus for the images.
June 2014

 

 

 

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