Drosera pauciflora

Banks ex DC.

Family : Droseraceae (Sundew family)
Common names
: sundew (Eng.); sondouw, vlie ë vangertjie (Afr.)

Flower

Drosera pauciflora is another large-flowered, winter-growing carnivorous plant from South Africa.

Description
The basal rosette of this herbaceous, insectivorous plant is compact and made up of slender leaves up to 25 mm long and 8 mm wide. The leaves are narrowly egg-shaped with the narrowest point at the base. Leaf stalks and stipules are absent. The leaves bear both knob-ended and straight tentacles.

The erect, leafless flowering stem which arises from the centre of the rosette, up to 200 mm high, bears 13 large pink to mauve flowers with fringed styles in spring, and flowers profusely after fire.

Fringed styles close-up

Conservation status
This species is not threatened.

Distribution and habitat
Drosera pauciflora is endemic to South Africa and is only found in the Western Cape. The species is common in Darling, Paarl and Stellenbosch and can also be found near Piketberg. It occurs at altitudes from 611050 m.

Plant colonies can usually be found in damp exposed areas in seeps or on exposed flat and sandy areas amongst fynbos vegetation.

Growing habitat

Derivation of name and historical aspects
The genus Drosera was named by Linnaeus in 1753, and consists of ± 126 species of which 23 occur in South Africa. Drosera gets its name from the Greek word, droseros, meaning dewy. The specific name pauciflora, meaning few-flowered, gets its origin from the Latin words paucus meaning few and flora for flowered.

Synonymy includes Drosera acaulis sensu Raym.-Hamet and Drosera grandiflora Bartl .

Drosera pauciflora is closely related to Drosera cistiflora, but is easily distinguished from it by the lack of leaves on the flowering stem.

Ecology
Flowers are open briefly for a few hours with good sunlight. The flowers can be pollinated by insects, but are usually self-pollinated. When the seeds are ripe, their capsules open to release the fine, light-weight seeds which fall out and are dispersed near the parent plants. Probably the most interesting characteristic of this plant is its ability to digest the nutrients, especially the nitrogen it requires from insects caught in its stalked tentacles. Different types of glandular growths include marginal tentacles situated near the lamina margins, discal tentacles which are shorter and disc-like, usually on the upper leaf surfaces, digestive glands filled with red fluid and glandular hair-like growths on the inflorescence. The tentacles are sensitive and mobile. Their stalks end in a bulbous head in which the glandular cells occur. These glands secrete a glistening, sticky, clear fluid used to trap and retain prey. There is speculation that the fluid is slightly sweetly scented to attract insects. The fluid contains a weak acid and enzymes that digest the soft parts of the prey. The sensitive tentacles are able to detect caught prey and produce more dew to entrap their victim. Neighbouring tentacles then mobilize and slowly lean over to engulf the hapless victim. The lamina itself may also fold over to enclose or suffocate larger prey and allow for better absorption. As sensitive as these tentacles are, they are able to distinguish between a meal and other stimuli, for example, the leaf and tentacles do not respond to water droplets.

Uses and cultural aspects
Droseras make fascinating house and conservatory plants around the world, but are better suited to being grown outdoors. However, keep them under roof if you wish to retain their vivid red colouration . Plants can be brought indoors for short periods for display. Drosera pauciflora is a hardy winter-growing carnivorous plant, but not necessarily the easiest for novices.

Drosera species have also been recorded for use against various ailments. Extracts of the leaves were used externally for warts, corns and sunburn. Disorders such as tuberculosis, asthma, coughs, eye and ear infection, liver pain, morning sickness, stomach conditions, syphilis, toothache and intestinal problems were treated internally with teas or extracts made from the leaves. The tea was also used as a tranquilizer, and some believe that it has aphrodisiac properties. Antispasmodic agents have been found by scientists in some Drosera species.

Growing Drosera pauciflora

A very well drained sandy soil is the best growth medium; 2 parts sand or silica grit : 1 part peat or sphagnum moss, in 90150 mm pots are ideal. It is important not to over-pot plants. Taller rather than wider pots are ideal for Drosera to thrive and to accommodate their few, but long roots.

Place the potted plants in a shallow saucer filled with fresh water to keep them moist at all times during their growth season.The author has had the best success growing this species without saucers, but watering every other day. Drosera pauciflora roots are prone to rotting if they are water-logged. If using the saucer method, allow the saucer to dry out occasionally so that the medium can aerate. This will not harm your plants so long as the moisture content in the medium is still high.

Place in a northern or eastern direction for best sunlight if growing indoors. Grow in full sun to light shade outdoors. During the plants' dormant period in summer, remove pots from water trays, but do not allow soil to dry completely. The author allows for very minimal, light watering over the dormant phase. This technique has successfully kept plants alive over their dormant period and allowed mature plants to resprout in the following winter. Other growers recommend removing roots and tubers and keeping them in a sealed container in a cool environment.

Sundews are easily propagated by seed. Prepare a 90 mm pot with growth medium; water well. In autumn sow fresh seeds on the surface of moist growth medium. Do not cover with growth medium. Place in a semi-shady position, and seeds should germinate in 24 weeks.

Once young leaves develop, pierce the plastic to allow for acclimatization and hardening off. Acidic or epiphytic foliar feed may be used at ¼ recommended strength once a month.

Ironically, the carnivorous plants are attacked by insect pests. Aphids, mealy bug and thrips cause deformity in new growth. Treat with a diluted pesticide or remove pests by hand. Never use a soap-based insecticide. Drying out can cause drooping and the decrease in mucilage production. Watering and keeping the plant moist will revive them. Dew production may stop after transplanting or if the leaves come into contact with inquisitive hands. New foliage will, however, grow and continue to produce dew.

References and further reading

  • Bean, A. & Johns, A. Stellenbosch to Hermanus. 2005. South African Wildflower Guide 5. Botanical Society of South Africa, Cape Town.
  • Bond, P. & Goldblatt, P. 1984. Plants of the Cape Flora. A descriptive catalogue. National Botanic Gardens of South Africa, Cape Town.
  • Codd, L.E, De Winter, B. & Killick, D.J.B. 1970. Flora of southern Africa 13. National Botanic Gardens Kirstenbosch, Cape Town.
  • D'Amato, P. 1998. The savage garden: Cultivating carnivorous plants. Ten Speed Press, California.
  • Goldblatt, P. & Manning, J.C. 2000. Cape plants. A conspectus of the Cape flora of South Africa. Strelitzia 9. National Botanical Institute, Pretoria.
  • Stearn, W.T. 2002. Stearn's dictionary of plant names for gardeners. Timber Press, Oregon.

 

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Kirstenbosch National Botanical garden

Photographs by Adam Harrower

October 2012

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