Drosera is a genus in the Droseraceae family of carnivorous plants. Members of this family lure, capture and digest insects to supplement the poor mineral nutrition they obtain from their native soils. They are known as sundews because their glandular leaf hairs glisten like dew in the sun. Flowers are held far above the leaves on a long stem. They open in response to sun and are short lived. There are more than 50 tuberous species from Australia. These species grow in winter wet, dry summer conditions and are dormant in summer. They have many different growth habits. Some are erect with self-supporting stems with small leaves scattered along their length. Another group climbs over plants as though they were vines. There are also fan-leafed and rosetted forms. Tubers are pea to walnut-sized and sometimes grow large enough that stolons are formed that produce additional tubers. Some species continue to grow each year from the same tuber and other species replace the tuber each year.
Seeds of southwestern/western Australia do not germinate for 8 months or so. This coincides with the dry summer period. The seeds will not germinate even if pretreated with smoke or kept wet (John Conran). Presumably, South African species would behave in the same manner. Seeds should be surface sown on a mix of 1:1 peat and sand (finer grained sand seems to work better). Set the pot in a tray with about 1 inch (25 cm) of water and keep out of the rain, which could splash the seeds out of the pot. Alternatively, germination could be done by growing the seeds on water solidified with agar. Care must be taken to only add seeds to agar and not other plant pieces as that attracts fungi. Even if fungi grow (underneath), the seeds will still germinate, given that the fungi do not grow over them. Once seedlings have produced a leaf or two, they can be pricked out and transplanted onto a 1:1 peat medium. Tubers can be planted in the same medium and the pot kept in a tray of water. When the plant starts going into dormancy, remove the pot from the tray of water and allow the medium to dry out, but keep the medium from completely drying out in the summer. Return the pot to the tray of water during the growing season. Allow the plants to capture insects to obtain nutrients. It is not advisable to fertilize. Although can be done, just a little too much will kill the plants.
Drosera cistiflora is a South African species that is technically not a bulb, but it is a species that dies back in the summer to thick wiry roots from which they return each year. I’m including it since it behaves in a similar fashion to the tuberous Australian species with a summer dormancy and because it has such beautiful large (2 to 3 in., 5 to 7.6 cm) cup-shaped colorful flowers (purple to rose to white to deep red.) Leaves are formed in a rosette pressed flat on the surface. The first two photos were taken near Brackenfell August 2006 after a previous burn in the area. The next two were taken near September 2006 on the way to Darling where there was a grassy field of Geissorhiza radians. Photos 1-5 taken by Mary Sue Ittner. The last photo was taken near Darling by Cameron McMaster.
Drosera macrantha is a tuberous climbing species that scrambles over surrounding vegetation. It grows from 40 to 120 cm. tall and has small cup-shaped golden green leaves in alternate whorls of three. Five to 30 white to pink, occasionally red flowers are on the end of branched stems. This species is found in Victoria, Tasmania, South Australia, and southwestern Western Australia. It grows in many habitats: open woodland, in shrubland, near granite outcrops, and in well drained sandy soil. Flowering is from June to November. Photos taken by Bob Rutemoeller and Mary Sue Ittner of plants we think are this species in southwestern Western Australia September 2007 although Drosera pallida is found in some of the same areas and looks very similar so we could be picturing that instead. The last photo was taken at William Bay National Park.
Drosera menziesii is an erect tuberous species with undulating red leafy stems 10 to 30 cm long, circular sticky hairy leaves in groups of three and white, pink to reddish flowers up to 2.5 cm. across. This species grows in wet peaty sand, clay, or loam in swamps, forest, woodland, heath and granite outcrops in southwestern Western Australia. Flowering occurs from July-November. Photos taken by Bob Rutemoeller and Mary Sue Ittner of plants we think are this species in these National Parks in Western Australia: Stirling Range,Porongurup National Park, William Bay National Park September 2007.
Drosera peltata is from Australia, Tasmania, and New Zealand. It is a winter-growing species. In the San Francisco Bay Area, they tend to have a long dormancy, and not break the dormancy until about January, even if water was given in October. The photos below were taken by Nhu Nguyen.
Drosera spp. seen and photographed in the Stirling Range National Park in September 2007 by Mary Sue Ittner. There were erect species that were like shiny towers. One of them pictured in the last two pictures had a flower that is white with pink markings and reddish leaves and stems and could be Drosera menziesii.
Drosera sulphurea is a tuberous species found in coastal areas of southwestern Western Australia where it grows in sandy loam. It grows to 40 cm., has green shield shaped leaves in threes, yellow flowers to 2.5 cm. in sprays. and blooms in September. Photos taken by Bob Rutemoeller and Mary Sue Ittner of what we think could be this species at William Bay National Park, Western Australia, September 2007.
Drosera whittakeri is a tuberous species found in Victoria and South Australia, Australia. It grows in a variety of habitats including heathland and open forest. It has basal rosettes of bright green to red spathulate hairy leaves to 2.5 cm. White open petalled fragrant flowers grow on short recurved stems in winter and spring. Photos by Bob Rutemoeller and Mary Sue Ittner of what we think is this species taken in the Grampians October 2007.