Manual of the New Zealand Flora/Droseraceæ
Order XXVI. DROSERACEÆ.
Herbs, rarely undershrubs. Leaves alternate, often rosulate, stipulate, usually furnished with glandular irritable hairs; vernation circinate. Flowers regular, hermaphrodite. Calyx 4–5-partite or divided into 4–5 free sepals, imbricate, persistent. Petals the same number, hypogynous, rarely perigynous, free or sometimes connate at the base. Stamens 4-5, rarely more, hypogynous or perigynous, rarely epipetalous. Ovary free or nearly so, 1–3-celled; styles 1–5, simple or bifid or multifid; ovules numerous, attached to parietal placentas equalling the styles in number. Capsule membranous, loculicidally 3–5-valved; seeds numerous, albuminous; embryo straight, axile.
A small order, comprising 6 genera and about 120 species, distributed over the whole world with the exception of Polynesia, but most abundant is Australia. The whole of the species capture insects, usually by means of glandular viscid and irritable hairs; but in some cases, as the well-known Venus's fly-trap (Dioncsa muscipula) by rapidly closing laminae, which shut the insects as it were in a box. For a full account reference should be made to Mr. Darwin's well-known book on "Insectivorous Plants." The single New Zealand genus is the largest in the order, and has an almost world-wide distribution.
1. DROSERA, Linn.
Herbs, either scapigerous or with a leafy stem. Leaves rosulate or alternate, covered with numerous hair-stalked glands which secrete a drop of transparent viscid fluid. Stipules wanting or adnate to the base of the petiole. Flowers solitary or in terminal often one-sided racemes or cymes. Calyx 4–5-partite. Petals 4–5, hypogynous or rarely perigynous, marcescent. Stamens the same number. Ovary ovoid or globose, 1-celled; styles 2–5, free or connate below; ovules numerous, on 2–5 parietal placentas. Capsule oblong, 2–5-valved. Seeds minute; testa lax.
Species about 100, scattered over the whole world, but most abundant in Australia. Of the 6 found in New Zealand, 1 is endemic, the remaining 5 extend to Australia.
|* Scape 1-flowered.|
|Leaves spathulate. Calyx-lobes short, rounded. Styles 3, multifid||1. D. stenopetala.|
|Leaves linear-ligulate. Calyx-lobes long, linear-oblong. Styles 3; stigmas capitate||2. D. Arcturi.|
|Minute. Leaves rosulate, orbicular. Styles 4; stigmas clavate||3. D. pygmæa.|
|** Scape several- or many-flowered.|
|Leaves rosulate, spathulate. Styles 3, 2-partite||4. D. spathulata.|
|Leaves long, very narrow-linear, forked or dichotomous||5. D. binata.|
|Stem leafy. Leaves lunate, peltate. Flowers pink. Styles, 3 penicillate||6. D. auriculata.|
1. D. stenopetala, Hook. f. Fl. Nov. Zel. i. 19, t. 9.—Stemless; rootstock short, stout. Leaves 1–4 in. long or more; petioles slender, flat, perfectly glabrous; blade ¼–¾ in., spathulate, the margins and upper surface densely covered with long glandular hairs. Scape 1–6 in. long, exceeding the leaves, slender, glabrous, 1-flowered. Flowers ⅓ in. diam., white. Calyx broadly campanulate, 5-lobed, glabrous; lobes short, rounded. Petals linear-spathulate; claw very long and narrow. Styles 3, multifid almost to the base.—Handb. N.Z. Fl. 63; Kirk, Students Fl. 145.
North Island: Ruahine Range, Herb. Colenso! W. F. Howlett. South Island: Not uncommon on the higher central and western mountains, from Mount Arthur southwards. Stewart Island: Petrie, Kirk! Auckland Islands: Hooker, Le Guillon, Kirk. Altitudinal range 2500–5000 ft. in the South Island, but descending almost to sea-level in the Auckland Islands. December–February.
2. D. Arcturi, Hook. in Journ. Bot. i. (1834) 247.—Stemless. Rootstock short or 1–2 in. long, clothed with the ragged bases of the old leaves. Leaves 1–4 in. long, erect, linear-ligulate, obtuse, upper portion covered with glandular hairs, lower half glabrous; petiole almost as broad as the blade; early leaves shorter and broader, sometimes quite glabrous. Scape 2–6 in. high, slender, 1-flowered or very rarely 2-flowered. Flowers ⅓ in. diam., white. Calyx divided almost to the base; lobes 4, linear-oblong. Petals oblong or obovate, slightly exceeding the calyx. Styles 3–4, short; stigmas broad.—Ic. Plant. t. 56; Hook. f. Fl. Nov. Zel. i. 20; Handb. N.Z. Fl. 63; Benth. Fl. Austral. ii. 456; Kirk, Students' Fl. 145. D. polyneura, Col. in Trans. N.Z. Inst. xxii. (1890) 460. D. Ruahinensis, Col. l.c. xxviii. (1896) 593. D. ligulata and D. atra. Col. l.c. xxxi. (1899) 269.
North Island: Ruahine Range, Colenso, Olsen! Rangipo Plain, Petrie! South Island, Stewart Island: Abundant in mountain districts throughout. Altitudinal range usually from 2000–5000 ft., but descends almost to sea-level on Stewart Island. Also found in Australia and Tasmania.
3. D. pygmæa, D.C. Prodr. i. 317.—A very minute stemless species forming flat rosettes ⅓–½ in. diam. Leaves numerous, densely crowded; petioles short, slender; limb 1–1 diam., upper surface covered with glandular hairs; stipules large, scarious, deeply lobed, forming a beautiful silvery cone in the centre of the rosette. Scapes 1–4, glabrous, filiform, ½–¾ in. high, 1-flowered. Flowers minute, white. Calyx 4-lobed. Petals slightly longer than the calyx. Styles 4, short, clavate. Capsule oblong,. 4-valved.—Hook. Fl. Nov. Zel. i. 20; Handb. N.Z. Fl. 63; Benth. Fl. Austral. ii. 457; Kirk, Students Fl. 146.
North Island: Cape Maria van Diemen, Colenso! Te Paua, Parengarenga, T. F. C.; near Ahipara, H. Carse! R. H. Matthews! South Island: Bluff Hill, Kirk. December–January. Also in Australia and Tasmania.
A beautiful little plant, probably not uncommon in moist peaty situations, but very easily overlooked.
4. D. spathulata, Labill. Nov. Holl. Pl. i. 79, t. 106, f. 1.—Stemless. Leaves numerous, crowded, rosulate, ⅓–¾ in. long; blade 1–1 in., spathulate or obovate or orbicular-obovate, narrowed into a broad and flat petiole of varying length, upper surface and margins covered with glandular hairs; stipules scarious, narrow, laciniate. Scapes 1 or several, 1–6 in. high, usually bearing a second raceme of 3–7 flowers, but often 2–3-flowered or even 1-flowered. Flowers small, 1 in. diam., white or rose. Calyx deeply divided; lobes 5, linear-oblong. Petals 5. rather longer than the calyx. Styles 3, 2-partite almost to the base, branches entire or again forked.—Hook. f. Fl. Nov. Zel. i. 20; Handb. N.Z. Fl. 63; Benth. Fl. Austral. ii. 459; Kirk, Students' Fl. 146. D. propinqua, R. Cunn. Precur. n. 620. D. minutula. Col. in Trans. N.Z. Inst. xxi. (1889) 81. D. triflora. Col. l.c. xxii. (1890) 461.
North and South Islands, Stewart Island: From Mongonui southwards, but often local. Sea-level to 4500 ft. November–January. Also in Australia and Tasmania.
Mountain specimens are often much reduced in size, with shorter and broader leaves, 1–2-flowered scapes, and broader calyx-lobes; but they pass by insensible gradations into the ordinary form.
5. D. binata, Labill. Nov. Holl. Pl. i. 78, t. 105, f. 1.—Stemless. Rootstock short, emitting numerous fleshy roots. Leaves all radical, erect; petioles 2–5 in. long, slender, glabrous; blade 2–4 in., divided to the base into 2 narrow-linear segments 1–1 broad, which are simple or again forked, upper surface and margins clothed with long glandular hairs. Scapes exceeding the leaves, 6–18 in. high, slender, glabrous, bearing a loose cyme of few or many rather large white flowers ⅓–½ in. diam. Calyx deeply 4–5-lobed; lobes oblong, entire or lacerate at the tips. Petals 4–5, obovate, twice as long as the calyx. Styles usually 3, penicillate.—Bot. Mag. t. 3082; Hook. f. Fl. Nov. Zel. i. 20; Handb. N.Z. Fl. 64; Benth. Fl. Austral. ii. 461; Kirk, Students Fl. 146. D. intermedia, R. Cunn. Precur. n. 621. D. flagellifera, Col. in Trans. N.Z. Inst. xxiii. (1891) 384.
North and South Islands, Stewart Island: From the North Cape southwards. Sea-level to 2500 ft. November–February. A common Australian and Tasmanian plant.
A very handsome and conspicuous species. Mr. Colenso's D. flagellifera, as shown by the specimens in his herbarium, is merely a small state with narrower and often simple leaf-segments, and can be matched in any locality where the plant is plentiful.
6. D. auriculata, Backh. ex Planch. in Ann. Sci. Nat. Ser. 3, ix. (1848) 295.—Rootstock slender, terminating in a globose tuber deep in the ground. Stems leafy, erect, flexuose and wiry, simple or sparingly branched, perfectly glabrous, usually 6–18 in. high but sometimes much longer and almost climbing. Radical leaves rosulate, sometimes reduced to linear scales; blade orbicular or reniform, glandular; petiole short, broad, flat. Cauline leaves alternate, on longer filiform petioles, peltate; blade ¼ in. diam., broadly lunate, the two angles with glandular-ciliate appendages, margins fringed with long glandular hairs. Flowers ¼–⅓ in. diam., pink, in terminal 3–8-flowered racemes. Sepals 5, oblong, entire or minutely toothed. Petals twice as long as the sepals, obovate or obcordate. Styles 3, divided to below the middle into numerous dichotomous lobes.—Hook. f. Fl. Nov. Zel. i. 21; Handb. N.Z. Fl. 64; Benth. Fl. Austral. ii. 465; Kirk, Students' Fl. 146. D. circinervia, Col. in Trans. N.Z. Inst. xxvi. (1894) 314. D. stylosa, Col. l.c. xxviii. (1896) 593.
North and South Islands: Abundant as far south as Banks Peninsula. Sea-level to 1500 ft. November–January. Also plentiful in Australia and Tasmania.