Drosera
Drosera capillaris
catch-fly, dew-threads, droséra, rossolis, sundew
pink sundew
prostrate;
stipules free from or adnate to petioles to 1 mm, then breaking into setaceous segments 3–5 mm;
petiole differentiated from blade, 0.6–4 cm, sparsely glandular-pilose;
blade broadly spatulate to orbiculate, 0.5–1 cm × 3–5 mm, usually at least slightly longer than broad, usually shorter than petiole.
2–20-flowered;
scapes 4–20(–35) cm, glabrous.
10 mm diam.;
sepals connate basally, oblong-elliptic, 3–4 × 1–2 mm, apex obtuse, glabrous;
petals usually pink, sometimes white, obovate, 6–7 × 2–3 mm.
obovoid, splitting between placentae.
4–5 mm, longer than sepals.
20–70, minute.
brown, ellipsoid to oblong-ovoid, asymmetric, 0.4–0.5 mm, coarsely papillose-corrugated, 14–16-ridged.
both surfaces in strong sunlight, greener in shade (except D. tracyi, which lacks red pigment even in full sun), unlobed, suborbiculate, orbiculate, spatulate, or obovate, or cuneate to linear pink, or rose to pinkish lavender;
stamens 5, usually connate basally;
gynoecium 3-carpellate;
styles 3, deeply bifid;
stigma capitate.
= 10.
= 20.
Drosera
Drosera capillaris
Species ca. 170 (8 in the flora).
Species of Drosera are concentrated in Latin America, South Africa, Madagascar, Australia, and New Zealand.
Droseras, like all carnivorous plants, have leaves that attract, catch, digest, and absorb nutrients from small, mostly arthropod prey. They are characterized by gland-tipped multicelled hairs that move in response to stimuli and that catch and appress prey to the leaf blade, where sessile glands secrete enzymes that dissolve the soft tissues. The released nutrients enhance growth by supplementing those available from the poor soils where they grow.
All species of Drosera are capable of moving their trichomes in response to contact with digestible prey. According to C. (1875), this movement can be induced by the mere
touch of a part of a small insect with a single trichome. Besides having trichome movement, some species are able to curl their leaf blades to various degrees in order to maximize contact with prey.
Some species of Drosera may act as annuals, especially if the habitats dry out. The plants can be locally abundant. In most species, the flowers open only in the mornings on sunny days, or not at all on overcast days, and fruits may form from self-pollination. Some species, notably D. intermedia, may exhibit vegetative proliferation, portions of the flowers developing into leaves or plantlets. Some species form over-wintering buds called hibernaculae, requiring a cold period to break dormancy.
Some species of Drosera are reportedly utilized in herbal medicines to produce cough preparations and treat lung and skin ailments.
F. E. Wynne (1944) showed that seeds of North American Drosera are diagnostic for each species. The following key is adapted from various sources, and the species are presented in alphabetic order. Natural hybrids are rare in Drosera, and usually are sterile.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Drosera capillaris is the most-frequently encountered species of the genus in the South in moist habitats that can support carnivorous plants, especially in fire-maintained pinelands. Plants can be quite small, or form surprisingly large and robust rosettes (to 12 cm broad) in some places along the Gulf Coast. It is disjunct from the Coastal Plain to Arkansas and Tennessee, as are several other species from coastal wetland habitats. Since the leaf blades of D. capillaris can be somewhat orbiculate, it may be confused with the much more northern D. rotundifolia, which grows more typically in sphagnum (although in its northern range it often grows on moist sand substrates), has adnate stipules, white flowers, and forms hibernaculae.
Drosera capillaris is easy to grow, often behaving as an annual.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaf blades filiform, not differentiated from petioles; stem base bulbose-cormose (from expanded petiole base); petals 7–17(–20) mm | → 2 |
1. Leaf blades linear or suborbiculate to obovate, elongate-spatulate, or cuneate, usually differentiated from petioles; stem base not bulbose-cormose; petals 3–7(–8) mm | → 3 |
2. Petals 7–10(–12) mm; leaf blades 8–25(–30) cm × 1 mm, glandular trichomes red to reddish purple, drying dark brown; scapes 6–26 cm. | D. filiformis |
2. Petals 12–17(–20) mm; leaf blades 30–50 cm × 1–2 mm, glandular trichomes pale green, drying pale greenish brown; scapes 25–60 cm. | D. tracyi |
3. Scapes stipitate-glandular; stipules absent or reduced to minute hairs; seeds black, crateriform. | D. brevifolia |
3. Scapes glabrous; stipules present; seeds reddish brown, light brown, brown, or black, striate, areolate, papillose, crateriform, or ridged | → 4 |
4. Leaf blades suborbiculate, (broader than long); seeds finely longitudinally striate. | D. rotundifolia |
4. Leaf blades linear, orbiculate, or spatulate to obovate or elongate-spatulate (longer than broad); seeds areolate, crateriform, or papillose | → 5 |
5. Stipules adnate to petioles | → 6 |
5. Stipules free from petioles or essentially so | → 7 |
6. Leaf blades obovate to elongate-spatulate; seeds fusiform, striate-areolate, 1–1.5 mm. | D. anglica |
6. Leaf blades linear; seeds rhomboidal or oblong-obovoid, crateriform, 0.5–0.8 mm. | D. linearis |
7. Plants always rosulate; petioles flat, sparsely glandular-pilose; petals usually pink, 6–7 mm; seeds coarsely papillose-corrugated, 0.4–0.5 mm. | D. capillaris |
7. Plants rosulate when young, developing leafy stems 1–8(–20) cm; petioles filiform, glabrous; petals white, 3–6 mm; seeds uniformly papillose, 0.7–1 mm. | D. intermedia |
CA
OR
WA
Flora NW
PNW Herbaria
WildflowerSearch
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USDA Plants Database
LA Plants
MD Biodiversity
