Drosera regia

A sundew that stands apart

Drosera regia, the king sundew ^[6], is one of the most distinctive plants in the genus. ICPS calls it the most spectacular of the easy-to-grow sundews, with leaves easily 45 cm (18 in) long on plants grown outside or in a very bright greenhouse, and flower spikes a little taller than the leaves ^[2]. Robert Gibson, comparing it with the Australian D. arcturi in 1999, recorded linear leaves up to 60 cm long and 2 cm wide growing from a horizontal woody rhizome, with a few thick, fleshy roots ^[4].

Its leaves are built differently from most sundews. They are folded along their length and uncurl only weakly as they grow. Small, red, stalkless glands cover the underside of the blade, except on either side of the prominent midrib, as well as the sepals and bracts. Both the blade and the stalked tentacles can fold over prey ^[4]. The flowers are large and pink, with unscented petals 2 to 3 cm long and three spreading styles held beyond the five stamens ^[4]. Gibson also notes that its operculate pollen separates it from all other members of the genus ^[4].

That oddness has a history. E. L. Stephens described the species in 1926 and placed it in section Psychophila alongside D. arcturi; in 1994 it was given a section of its own, Regiae ^[4]. In a 2003 DNA study, D. regia clustered with most Australian species near the base of the genus’s evolutionary tree, which the authors took as a sign that sundews began in Africa or Australia ^[7]. ICPS adds that some botanists have proposed moving it out of Drosera altogether ^[2], and WCVP records one such name, Freatulina regia, as a synonym ^[1]. The practical lesson, according to ICPS, is that you cannot assume it grows like other sundews ^[2].

Two seeps in the Cape mountains

ICPS says the species is or was known from only two sites in the Bain’s Kloof range near Cape Town, at 500 to 900 m ^[2]. South Africa’s Red List places it in the Bain’s Kloof and Slanghoek mountains, in damp, swampy ground within Hawequas Sandstone Fynbos ^[3]. ICPS compares the sites to Darlingtonia habitat in California and Oregon: hillside seeps where water flows through the soil, full sun, mild days and cool nights, and wet peat and gravel under small shrubs and dense rush-like plants ^[2].

Gibson visited the lower site in July 1997, in the southern winter. The sundews grew in peaty sand along the edges of cobbles and in gravel over wet peat, among grasses and sedges, restios and a Leucadendron. The plants were just coming out of dormancy, with lengthening buds and only a few open leaves. He notes that frost is infrequent there, that the habitat is periodically burnt, and that D. regia can resprout from undamaged roots after fire ^[4].

South Africa’s Red List rates it Rare, not threatened. Its extent of occurrence is about 60 km² and its habitat is well protected. Collecting at well-known sites is named as a potential threat, though many plants likely grow in inaccessible parts of the rugged range ^[3]. It was assessed as Rare in 1996 and Least Concern in 2009 before the 2011 reassessment ^[3]. It is not covered by CITES ^[5].

Growing it like a pitcher plant

ICPS’s central advice is to grow D. regia much like a Sarracenia, including fertilizer in the soil, with some protection in very hot weather and in very cold weather ^[2]. In USDA zone 9 and warmer it can stay outdoors all year, and plants that have formed their loose winter buds survive light frosts; if an unusual light freeze kills the main growing point, the plant can regrow from the roots. In zone 8 and colder it needs serious winter protection. The ICPS author, in zone 7, keeps mature plants in a garage window with supplemental light for five to six months each year, and says a heated greenhouse also works ^[2]. A grower writing for ICPS also lists it among the plants that succeeded outdoors all year in a Pacific Northwest bog garden ^[8]. See the dormancy guide.

Pots and soil need more thought than for most sundews. The plant likes a light mix in large, tall pots, such as loose long-fibered sphagnum or peat with 50% sand or perlite. A #1 nursery pot, about 16 cm wide and 18 cm tall, is not too big for a mature plant; small plants under lights do well in 9 cm tall pots. Some growers stand the pots in water, others let the trays dry between waterings or use clay pots. ICPS suggests that the plant needs wet soil but tolerates airless, waterlogged conditions less well than most sundews, and that the roots may be heat sensitive ^[2]. See repotting.

Fertilizer, the big exception

The ICPS author knows of no other sundew that benefits from soil fertilization. Plants without soil fertilizer that catch little prey need very regular foliar feeding with dilute liquid fertilizer, live insects or dried bloodworms; neglected, they decline and eventually die. The ICPS author puts 4 to 6 high-nitrogen slow-release fertilizer pellets per plant or pot each spring. Fertilizer leaking into a shared water tray can harm other sundews and Venus flytraps, so keep D. regia in its own tray or with Sarracenia ^[2]. The feeding guide explains why most carnivorous plants should not be fertilized this way.

Flowers, seed and root cuttings

The sources disagree about pollination. ICPS describes the flowers as self-fertile, but with stigmas and anthers that mature at different times, so you need two flowers open together: use yesterday’s pollen on today’s stigma ^[2]. Gibson, citing experiments reported to him by Eric Green of Cape Town, writes that the pollen is compatible only with genetically different plants, and that the flower’s layout minimizes self-pollination ^[4]. Having two different clones in flower avoids the question.

Seed has a reputation for being difficult, but the ICPS author finds it the easiest sundew to start from seed: sown on sand and chopped sphagnum under lights, it germinates in a few weeks without cold treatment ^[2]. Seedlings that stall after a few true leaves are, in his view, starving rather than diseased. He adds five slow-release pellets to each 8 cm pot once the seedlings have four true leaves ^[2]. See sowing seeds.

Root cuttings are the easiest vegetative method. ICPS lays 2 cm pieces of older root about 1 cm deep in loose long-fibered sphagnum, and moves the new plants to a peat mix with a few fertilizer pellets once their leaves are 2 to 3 cm long ^[2]. On leaf cuttings, ICPS’s own pages differ: the propagation guide calls them particularly difficult ^[9], while the growing guide reports success with leaves floated in water and rot on soil ^[2]. The registered cultivar ‘Big Easy’, a compact clone with leaves up to 23 cm that never went dormant or flowered for its registrant, has been propagated both from floating leaf cuttings and from pieces of root ^[10]. The sundew leaf cuttings guide covers the floating method. For how this plant compares with other sundews, see the genus overview.