Sparaxis grandiflora subsp. grandiflora
Sparaxis grandiflora (D.Delaroche) Ker Gawl. subsp. grandiflora
Common names: Cape buttercup, sparaxis (Eng.); botterblom, ferweel, ferweeltjie, fluweeltjie, perskalkoentjie, perskalossie (Afr.)
Sparaxis grandiflora is indeed an attractive species and it is not surprising that it was introduced to Kew Gardens as early as 1758. However, as Du Plessis & Duncan (1989) noted when referring to S. grandiflora subsp. grandiflora , 'this very striking species deserves more attention from horticulturists'. Despite it being arguably the most spectacular, this deep plum-red subspecies of S. grandiflora has to this day very rarely been seen in its pure form in cultivation.
Considering its extreme endemism and few known localities, further conservation efforts both in and ex situ are necessary to ensure that the magnificent presence of this showy species continues to captivate its viewer well into the future.
Sparaxis grandiflora subsp. grandiflora is a deciduous geophytic plant where the underground storage organ is a corm i.e. a vertical underground stem with papery leaves, as opposed to a bulb where the underground storage organ is a bud with thickened fleshy scales. The corm is spherical in shape, about 13 mm in length and diameter and possesses a finely fibrous outer coating. Cormlets are not produced in large numbers, if at all.
The species produces more or less ten smooth, light green, sword to sickle-shaped leaves that taper to a sharp point at their apices. The leaves are about 60-200 x 10 mm and are ranked in two vertical rows on opposite sides of their central axis to form a fan-shaped structure. The upright plants are less robust than those of the other subspecies and grow to approximately 250 mm.
The flowers are regular, with the circular arrangement of six tepals united at the base to form an open flower with a very short flower tube. The tepals are almost equal in size and shape, the latter resembling that of a spathula but with rounded tips (cf. S. grandiflora subsp. violacea that has spathulate flowers with slightly pointed tips). The flowers are unscented and vary in colour from plum-red to white to mauve; the red form being the most abundant.
They are arranged in a cluster on the unbranched main stem from which each flower arises almost directly, being suspended individually by only a very short flower stalk. A series of dry, membranous bracts clasp the outer base of each flower from the point where the flower stalk meets the main stem. The male reproductive parts are vertically oriented and separate from each other, and the female reproductive part that is receptive to pollen, the stigma, is held by the style to one side of the central axis of the flower. In the event of fertilization taking place during the flowering period from late August to early October, fruit in the form of a capsule containing large, globe-shaped, smooth and shiny seeds will be produced thereafter.
It grows rapidly from seed and can live for approximately 10 years.
The species presently has a Red Data Book status of Vulnerable, owing to its location being confined to 8 localities within the limits of the Tulbagh Valley . This was not always the case, however, as the subspecies used to be more widespread and once grew in abundance between Tulbagh and Wolseley. Sadly, owing to agricultural expansion in the form of vineyards and wheatfields, most of its remaining habitat consists of small isolated areas of natural veld that occur between agricultural fields. These fragments of natural vegetation are severely impacted by pesticide drift and excessive nutrient overloading caused by fertilizer run-off from adjacent farmlands. This may affect the plants directly, but may also poison either the underground larval form or adult pollinators. Conservation efforts to save the subspecies would be in vain if one cannot ensure the survival of the pollinators.
Grazing continues to pose a problem at one of the localities and further expansion of vineyards and loss of habitat to olive groves are potentially threatening its future.
In 2005, as part of the Tulbagh Renosterveld Project, CREW confirmed the presence or absence of the plants at previously known localities and found localities unknown prior to commencement of the project. The data collected by CREW has contributed to providing a more accurate and higher Red Data List status for the species and hence alerted conservationists and local farmers to the importance of preventing further decline of the extant populations. CREW has informed the Millenium Seed Bank project of its status and seed will be collected for ex situ cultivation purposes later this year.
Distribution and habitat
Sparaxis grandiflora subsp. grandiflora is found on seasonally damp or waterlogged clay flats and slopes in shale renosterveld in the Tulbagh Valley in the Western Cape, where it receives winter rainfall.
Derivation of name and historical aspects
Sparaxis is one of the smaller genera of the family Iridaceae. The Iris family is a large group that is well represented in southern Africa and includes well-known genera such as Moraea , Watsonia and Gladiolus. The genus Sparaxis occurs only in the Cape Province and includes fifteen species. The extent of their occurrence ranges from Nieuwoudtville in the Northern Cape to Bredasdorp in the southwestern Cape.
Of all the species, Sparaxis grandiflora is the most variable and widespread. When Peter Goldblatt revised the genus Sparaxis in 1969 he recognized that distinct races of S. grandiflora had evolved as a result of their geographical isolation from one another. He treated these forms as four separate subspecies, namely S. grandiflora subsp . acutiloba , subsp. fimbriata, subsp. grandiflora and subsp. violacea . The range of the four subspecies extends from the Olifants River Valley, Piketberg and Tulbagh in the north, south to the Cape Peninsula and east as far as Bredasdorp. Some of the distributions are more limited than others, subsp. fimbriata being the most widespread as it grows along the western coast belt from Piketberg to Cape Town.
The Sparaxis grandiflora complex is not the most common, however, with S. bulbifera being the most abundant and possibly the hardiest and most adaptable species of Sparaxis. It grows on clay or sandy soil and has a remarkable tolerance of disturbance and continues to grow in large colonies in damp areas throughout the Western Cape where it thrives on many road verges!
The name Sparaxis is derived from the Greek word sparasso, meaning one tear, pertaining to the lacerated bracts of the flower. The specific epithet grandiflora is derived from the Latin words grandis, meaning full-grown and florus, meaning flower. This refers undoubtedly to the relatively large flowers present in this species with respect to the rest of the genus. It is not surprising, considering the beauty of this species, that it was introduced into horticultural circles quite some time ago. It was first brought to Kew Gardens in 1758 and described by the Swiss botanist Daniel de la Roche in 1766 after he obtained specimens of numerous species from several people including Linnaeus. The type specimen is, however, unknown. Judging from his description of the species as having large, deep-violet flowers with tepals dilated at the tip, Goldblatt (1969) concluded that the form De la Roche described was subsp. grandiflora . He placed it in the genus Ixia, where all Sparaxis species described before 1805 were considered to belong before John Bellenden Ker, an English botanist, transferred the four species described at that point to a new genus, Sparaxis.
It was not long before Sparaxis grandiflora was cultivated in Holland, Austria, France and Britain. The species has also been illustrated for numerous botanical publications.
Following the subdivision of the species into four subspecies, it appears that it is generally Sparaxis grandiflora subsp. acutiloba, the yellow-flowered form of S. grandiflora that has been popular in horticultural circles. Manning, Goldblatt & Snïjman (2002) stated 'we have never seen the plum form (subsp. grandiflora ) in cultivation'. I have since discovered that this form has been cultivated, although only rarely, and has never been sold to the public. It has, however, been used more readily to produce hybrids together with S. elegans and S. tricolor .
A particularly famous breeder of Sparaxis is the late Oom (Uncle) Japie Krige, well-known for his success with hybridization experiments in the genus. In 1930 he planted two species, namely S. grandiflora subsp. grandiflora and S. elegans, adjacent to one another and within a few years, as a result of cross pollination, had produced hundreds of hybrids of the original parent plants. His colourful garden attracted thousands of visitors every spring and before long his hybrid forms were grown all over the world in New York, Scotland, Germany, Holland, France, South America, Australia, Singapore, Japan, Egypt and East Africa. Unfortunately the plants in his garden developed an unknown fungus infection in 1938 and he was advised not to reseed the Sparaxis hybrids.
Since Sparaxis grandiflora subsp. grandiflora has a very small distribution range, it is evident that conservation efforts are necessary to increase the numbers of unhybridized plants in ex situ collections in order to preserve the genetic integrity of this subspecies.
Although not much is known about the pollination biology of this species, one could hazard a guess from the large, brightly coloured flowers and the markings at the base of the tepals (as seen in many moraeas and spiloxenes) that beetles would be attracted to this species in order to carry out their foraging activities. Indeed, following personal observations where the vast majority of insects seen visiting the flowers were monkey beetles, it appears that they are the primary pollinators of these plants. These beetles are scarab beetles of the tribe Hopliini and, more specifically, form part of the furry fast-flying group of monkey beetles of the non-embedding guild. Because they do not embed themselves in the flower for long periods of time and instead actively move from flower to flower, they are as efficient as bees and flies as pollinators. The flower serves as a mating and feeding platform for the beetles, where the males tousle amongst the flowers for females, feed on pollen and possibly take in nectar.
The species of monkey beetle I observed foraging on the flowers were of the genera Lepithrix and Peritrichia. Species of these genera belong to the guild of monkey beetles that are attracted to yellow, orange, pink, white and blue flowers and are important pollinators of many geophytes. The markings at the centre of the flowers could play a role in attempting to increase the cross pollination of the plants by mimicking the beetles themselves. By doing so, the markings could deceive a beetle into thinking there were already others at the flower, hereby increasing the desirability of the flower not only for feeding purposes but also by providing a potential mate.
It is also probable that bees and/or wasps pollinate the flowers, not only owing to the flower colour, but also because the anthers are held vertically away from the main body of the flower in a position in which pollen could be strategically brushed against the sides or back of visiting bees (Jonathan Colville pers. comm.).
A study conducted by Goldblatt et al . (2000) found the pollination systems of Sparaxis grandiflora (as well as S. bulbifera and S. fragrans ) to be less specialized than those of some other species of Sparaxis, although 90% of insects pollinating sparaxis flowers in general were found to carry pollen of at least one other taxon of flowering plant, indicating that few of the species were specialized to attract a specific pollinator. The study conducted did not include subsp. grandiflora, however, and further study is necessitated in order to give an accurate account of plant-pollinator relationships in subsp. grandiflora.
Growing Sparaxis grandiflora subsp. grandiflora
Sparaxis grandiflora subsp. grandiflora is a winter-growing, summer-dormant species. For this reason, plant the seeds or corms in autumn between late March and early June. S. grandiflora subsp. grandiflora is recommended for cultivation in both gardens and containers.
In gardens: Place corms approximately 7 cm apart at a depth of about three times their height. Use a slightly acid soil mix that is light and drains easily. Improve drainage if necessary by mixing in large amounts of fine compost and medium grain river or industrial sand. One successful grower used broken peach pips (without the kernel) to improve texture. Choose a site with a slight slope to enhance drainage; a rockery is ideal. They prefer a position in full sun to flower well but can cope well in semi-shade as long as they receive at least a few hours of direct sunlight a day.
Water well after planting, then cease watering until the leaf shoot appears. After the shoot has emerged, add some bonemeal and a small amount of potassium sulphate. Avoid inorganic fertilizers. Water well once a fortnight during winter and spring in order to keep the soil permanently moist.
After the flowering season, when the leaves die back, stop all watering. Preferably remove corms from the ground every second year during the dormant period. If they are left in the ground, ensure that they are kept dry and protected against overheating. If your garden is wet in summer, remove the corms and store them until autumn. If the soil has good drainage and the corms are left in the ground, feed them with a few dressings of bulb food in order to encourage flowering the following year.
In pots: Pot corms in a medium consisting of two parts coarse river sand, one part loam and one part fine compost. Rather choose a loose, coarser mix than heavy, compacting soil. Make sure the drainage holes in the base of the container are large and place some bark or stones in the base of the container, then fill with the mix. If the soil has not been sterilized, pour boiling water into the pots to kill off most of the weed seeds. Plant corms at a depth of about 3 cm. Be sure to place the pots in an area where they will not overheat in summer and place them under cover in areas of heavy winter rainfall to prevent the corms from rotting. To prevent overheating, shade the base of the pot with stones or other potplants. Do not water in the dormant period and store containers in a cool dry area until March the following year.
Propagation: The species can be easily grown from seed and has been known to flower after one year of planting out (although they usually flower in the second spring). Sow seed in a seed tray in autumn, preferably in a sterilized medium of equal parts river or industrial sand and fine compost or loam. Cover with a layer of sand so that the seeds are at least 5 mm deep. Keep the seedlings in the seed tray for at least one full season (preferably two) before planting out into pots or the garden. Keep the seed tray out of the rain for the first season, in a bright airy place.
Sparaxis grandiflora subsp. grandiflora may produce cormlets. Remove them from the corm in the dormant period and store them until planting out in autumn, as for corms.
Pests, disease and other ailments: The species is relatively frost hardy and can be grown outdoors in mild parts of the northern hemisphere.
Pests do not pose a major problem to the species, although slugs and snails may cause extensive damage to the foliage. Sprinkle salt on the slug or snail, or place tobacco dust around the base of the plant. Mealy bugs and aphids may attack them, as may be the case for any geophytic plant.
Water in the mornings rather than late in the day, to help prevent disease.
Sparaxis grandiflora subsp. grandiflora is a spectacular form of S. grandiflora and would make an attractive garden plant particularly when planted in large numbers. Interplant with low-growing spring annuals such as Heliophila coronopifolia, Felicia elongata, Dimorphotheca pluvialis or intersperse amongst groundcovers such as Asystasia gangetica or Sutera cordata . Plant close together in groups of 25 to 50 to maximize the effect of the display. They should flower readily for about five years, although it may be difficult to keep them going thereafter. Hopefully one day the corms will be available for sale at nurseries [Rhoda McMaster (African Bulbs) and Rachel Saunders (Silverhill Seeds), pers. comm.].
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Caitlin von Witt
Custodians of Rare and Endangered Wildflowers (CREW)
Plant Type: Bulb
SA Distribution: Western Cape
Soil type: Sandy
Flowering season: Spring
PH: Acid, Neutral
Flower colour: Purple, Red, White
Aspect: Full Sun
Gardening skill: Average