North American Drosera.
Flowers regular, perfect, hypogynous, usually 5-merous. Calyx, corolla, and stamens withering-persistent. Stamens with subulate or filiform filaments and extrorse versatile anthers. Ovary 1-celled, many-ovuled, with 3-5 parietal placentae and twice as many styles or stigmas. Seeds minute, anatropous, stipitate. Annual, biennial, or Perennial insectivorous herbs of bogs and marshes; leaves circinate in vernation, alternate or usually basal, tufted, covered with long glandular hairs which exude a clear viscid secretion.
Four genera and about 100 species. Three genera are monotypic, Aldrovanda, and Drosophyllum of the old world, Dionaea of the se. United States
Petals white, pink, or purple, broadened distally, distinct or slightly united at base. Stamens 4-8, as many as the petals. Styles usually bipartite to the base. Ovules subglobose or ovoid in 2-5 rows on each placenta. Capsule usually 3-valved. Testa loose, variously reticulated and ornamented. Leaf-blades filiform to peltate; stipules scarious, variously fringed or divided, adnate or free (lacking in one of our species). Inflorescence a scorpioid cyme nodding at the undeveloped apex.
About 100 species, most abundant in Australia and S. Africa; also in S. Am. and Eurasia. (Name from the Greek, droseros, dewy, the glutinous exudation of the leaf-glands shining like dew-drops.) The seeds and stipules are useful in identification . Shape and size of seeds can be determined with a 10X lens; a higher magnification is necessary to observe the ornamentation described and illustrated.
Leaf-blades filiform, not distinct from the petiole. 1. D. filiformis
Leaf-blades expanded, distinct from the petiole.
Leaf-blades suborbicular, broader than long; seeds sigmoid-fusiform,
finely longitudinally striate. 2. D. rotundifolia
Leaf-blades linear, spatulate, or cuneate; seeds variously ornamented.
Stipules adnate.
Leaf-blades linear; seeds rhomboidal, crateriform, 0.5-0.8 mm. long.
3. D. linearis
Leaf-blades elongate-spatulate; seeds fusiform, areolate-striate, 1-1.5 mm.
long. 4. D. anglica
Stipules free or lacking.
Scape glabrous; stipules conspicuous, free
Flowers white, 7-8 mm. wide; seeds irregularly and densely covered with
long papillae, 0.7-1 mm. long. 5. D. intermedia
Flowers pink, 10 mm. wide; seeds papillose-corrugated with 14-16 ridges,
0.4-0.5 mm. long. 6. D. capillaris
Scape glandular-pubescent; stipules absent; seeds crateriform, 0.3-0.4 mm.
long. 7. D. brevifolia
1. Drosera filiformis Raf. Leaves erect, filiform, without distinction between blade and petiole, 8-25 cm. long, covered with long, purple, glandular hairs. Stipules adnate, fimbriate on the margins, formig matted brown wool at the base of the leaves. Scape 6-22 cm. long, bearing 4-16 flowers 1 cm. in diameter. Calyx and upper part of the pedicel glandular- pubescent. Sepals oblong to elliptic, glandular-pilose, 4-7 mm. long Petals purple, broadly ovate, erose at the apex. Seeds black, 0.5-0.8 mm. long, elliptic, abruptly caudate at both ends, coarsely crateriform, the pits in 16-20 lines.
Along the east coast from Mass. to Del.; S. C. to Fla. and La. July-Sept.
2. Drosera rotundifolia
2. Drosera rotundifolia L. Petioles 1.5-5 cm. long, flat, glandular-pilose. Leaf-blades 4-10 mm. long, broader than long and much shorter than the petioles. Stipules 4-6 mm. long, adnate, fimbriate along the upper half. Scape glaborous, 7-35 cm. long, bearing 3-15 lowers 4-7 mm. in diameter. Sepals oblong, 4-5 mm. long, obtuse. Petals white to pink, spatulate, longer than the sepals. Seeds light brown 1-1.5 mm. long , sigmoid-fusiform, finely and regularly longitudinally striate, shining with a metallic luster.
Common in bogs and swamps in n. N. Am. s. to S. C., Ga., Tenn.,
O., Ill., Mont., and Cal. June-Sept.
3. Drosera linearis
3. Drosera linearis Goldie. Petiole 3-7 cm. long, flat, glabrous. Leaves linear, 2-5 cm. long, about 2 mm. wide. Stipules 5 mm. long, adnate, fimbriate along the margins. Scape glabrous, 6-13 cm. long, bearing 1-4 flowers 6-8 mm. wide. Sepals oblong-elliptic, minutely glandular- denticulate, 4-5 mm. long. Petals white, obovate, 6 mm. long. Seeds black, oblong-obovate, rhomboidal, 0.5-0.8 mm. long, densely and irregularly crateriform.
Northeastern N. Am., s. to Me., Mich., and Wis. July-Aug.
4. Drosera anglica
4. Drosera anglica Huds. Petioles 3-7 cm. long , gla- brous or sparsely glandular-hairy. Leaves obovate to elongate- spatulate, 3-4 mm. wide, 15-35 mm. long. Stipules 5 mm. long, adnate the entire length, imbrate along the upper half. Scape glabrous, 6-25 cm. long, bearing 1-9 flowers 6-7 mm. in diameter. Sepals oblong, minutely glandular-denticulate, 5-6 mm. long. petals white, spatulate, 6 mm. long. Capsule minutely tuberculate. Seeds black, sigmoid- fusiform, 1-1.5 mm. longitudinally striate-areolate
Western N. Am., around the Great Lakes and in e. Canada. June-Aug.
[D. longifolia, B. & B. Rydb.]
5. Drosera intermedia
5. Drosera intermedia Hayne. Stem 1-8 cm. long, bearing leaves in a rosette or also at intervals for several centimeters along the stem. Petioles 2-5 cm. long, glabrous. Leaf-blades oblong-spatulate to obovate, 4-5 mm. wide, 8-20 mm. long, bearing long glandular hairs on the upper surface. Stipules adnate at the base for the first millimeter, then breaking into several setaceous segments 2-5 mm. long. Sepals oblong, 3-4 mm. long. Petals 4-5 mm. long. Seeds reddish brown, oblong, 0.7-1 mm. long, blunt at the ends, densely and irregularly covered with long papillae.
Northeastern N. Am.; around the Great Lakes and along the coast from Nf.
to Tex. July, Aug. [D. longifolia, Gray.]
6. Drosera capillaris
6. Drosera capillaris Poir. Petioles 0.6-4 cm long, sparsely glandular- pilose. Leaf-blades broadly spatulate, 5-10 mm. long, 3-5 mm. wide, usually shorter than the petioles. Stipules free, or adnate for the first millimeter, then breaking into numerous setaceous segments 3-5 mm. long. Scape glabrous, 4-20 cm. long, Bearing 2-20 flowers. Flowers pink, 10 mm. wide. Sepals oblong-elliptic, 3-4 mm. long, obtuse. Petals 6-7 mm. long. Capsule 4-5 mm. long, surpassing the calyx. Seeds brown, elliptic to oblong-ovate, 0.4-0.5 mm. long, asymmetric, coarsely papillose-corrugated in 14-16 ridges.
Common in the coastal area from se. Va. to Tex. May - Aug:
7. Drosera brevifolia
7. Drosera brevifolia Pursh. Petioles 5-10 mm. long, dilated, glabrous. Leaf-blades cuneate, 4-10 mm. long, usually longer than the petioles. Stipules absent or reduced to one or two minute setaceous segments. Scape 4-9 cm. long, bearing 1-8 flowers about 15 mm. in diameter. Sepals glandular- pubescent, oblong-ovate, 2.5-3.5 mm. long. Petals rose to white, obovate, 4-5 mm. long. Seeds black 0.3-0.4 mm. long obovate, oblong, caudate at base, crateriform, the pits in 10-12 rows.