Manual of the New Zealand Flora/Convolvulaceæ

by Thomas Frederick Cheeseman

Order LII. CONVOLVULACEÆ.

Herbs or shrubs, frequently twining, often with milky juice. Leaves alternate, exstipulate, wanting in Guscuta. Flowers regular, usually hermaphrodite, axillary, solitary or cymose, often large and showy. Calyx inferior, persistent, usually of 5 distinct imbricated sepals. Corolla gamopetalous, hypogynous, campanulate or funnel-shaped or rotate, limb shortly or deeply 5-lobed or almost entire, often plaited and contorted in bud. Stamens 5, inserted on the tube of the corolla and alternate with its lobes; anthers oblong, opening lengthwise. Ovary superior, usually surrounded by an annular disc, 2–4-celled, rarely 1-celled, sometiines divided into 2–4 distinct carpels; style single or 2; stigma capitate or 2-lobed or branched; ovules usually 2 in each cell or carpel, erect, anatropous. Fruit a 1–4-celled capsule, 2–4-valved or bursting transversely or irregularly, rarely succulent and indehiscent. Seeds erect; albumen scanty or wanting; embryo curved, cotyledons broad, much folded and crumpled (in Cuscuta the embryo is spiral and undivided).

A moderately large order, widely spread over the whole world, but most plentiful in warm or tropical climates. Genera 32; species about 800. As a rule, the roots abound in a milky and acrid juice, which is often strongly purgative and used in medicine, as jalap and scammony. In some species the roots are inert and edible, as the common sweet potato, so largely cultivated in all warm countries. Many species of Ipomœa and allied genera are grown for the sake of their large and showy flowers. All the New Zealand genera have a wide range.

* Leafy plants, twining or prostrate.
† Corolla plaited. Style single.
Ovary 2–4-celled. Stigma capitate, or lobes globose	1. Ipomœa.
Ovary imperfectly 2-celled. Stigmas 2, oblong, flat. Bracts large, enclosing the calyx	2. Calystegia.
Ovary 1-celled. Stigmas 2, linear, flat. Bracts small or wanting	3. Convolvulus.
†† Corolla rotate. Styles 2.
Ovary of 2 separate carpels	4. Dichondra.
** Leafless twining parasites.
Corolla small, campanulate	5. Cuscuta.

1. IPOMŒA, Linn.

Twining or prostrate herbs, rarely suberect. Leaves alternate, entire or lobed or divided. Flowers usually large and handsome, axillary, solitary or cymose. Sepals broad or narrow, equal or unequal, erect in fruit or rarely spreading. Corolla campanulate or funnel-shaped; tube long or short; limb entire or 5-angled, more rarely slightly 5-lobed. Stamens included or exserted, often unequal; filaments filiform or dilated at the base; anthers oblong or linear, ultimately twisted or straight. Ovary 2-celled, 4-ovuled, rarely 4-celled and 4-ovuled or 3-celled and 6-ovuled; style filiform; stigma entire and capitate, or shortly 2-lobed with globular lobes. Capsule globose or ovoid, 4- or rarely 2–3-valved. Seeds as many as the ovules or fewer, glabrous or pubescent.

Taken in a wide sense, this is a genus of between 300 and 400 species, spread through all warm climates. Both the New Zealand species have a wide range in tropical countries.

Leaves digitately divided	1. I. palmata.
Leaves obtusely 2-lobed, thick and fleshy	2. I. biloba.

The kumara or sweet potato (Ipomœa batatas, Lamk.; Convolvulus chrysorhizus, Forst.) was introduced by the Maoris from Polynesia when they first colonised New Zealand, and constituted their chief vegetable food when the country became known to Europeans. It is still extensively grown, but has no claim to be included among the indigenous species.

1. I. palmata, Forsk. Fl. Egypt. Arab. 43.—A slender glabrous twiner; stems many feet in length, the old ones more or less tuberculate. Leaves 1–3 in. diam., digitately divided almost to the base; lobes 5–7, lanceolate or elliptic-lanceolate, obtuse or subacute, entire or the outer ones irregularly lobed, rather membranous. Peduncles erect, 1–2 in. long, 1–3-flowered. Sepals ¼–⅓ in. long, ovate, obtuse or subacute. Corolla large, 2–3 in. diam., pale-purple with a darker centre. Capsule nearly ½ in. diam., ovoid-globose, glabrous, 2-celled. Seeds 2–4, villous.—Benth. Fl. Austral. iv. 415. I. pendula, R. Br. Prodr. 486; A. Cunn. Precur. n. 396; Raoul, Choix, 44; Hook. f. Fl. Nov. Zel. i. 184. I. tuberculata, Rœm. and Schultes Syst. iv. 208; Hook. f. Handb. N.Z. Fl. 199.

Kermadec Islands: Sunday Island, not uncommon on the cliffs, T.F.C. North Island: Sea-cliffs from the North Cape to the Bay of Islands and Hokianga. December–April.

An abundant plant in the tropics of both hemispheres, attaining its southern limit in New Zealand.

2. I. biloba, Forsk. Fl. Egypt. Arab. 44.—Perfectly glabrous; stems prostrate or trailing, sometimes 40 ft. long. Leaves on petioles 1–4 in. long; blade often broader than long, 1–4 in. across, orbicular or broadly obovate or oblong, emarginate or shortly and obtusely 2-lobed, thick and fleshy, prominently veined. Peduncles about as long as the leaves, 1–3-flowered. Sepals ovate, obtuse. Corolla 1–2 in. diam., broadly campanulate with a somewhat tubular base, purplish or pink. Capsule ½–¾ in. long, ovoid-globose, coriaceous, 2-celled. Seeds large, hairy.—I. pes-capræ, Roth. Nov. Sp. Plant. 109; Benth. Fl. Austral. iv. 419; Cheesem. in Trans. N.Z. Inst. xx. (1888) 171.

Kermadec Islands: Sunday Island, abundant in the sandy bays and on some of the cliffs, T.F.C. Plentiful on all tropical shores.

2. CALYSTEGIA, R. Br.

Prostrate or twining herbs, glabrous or nearly so. Leaves alternate, entire or rarely palmately lobed. Peduncles axillary, 1-flowered; bracts 2, large, persistent, enclosing the calyx. Flowers usually large. Sepals equal or the inner slightly smaller. Corolla campanulate or funnel-shaped; limb plaited, 5-angled or obscurely 5-lobed. Stamens included; filaments dilated at the base; anthers oblong. Ovary 1-celled or imperfectly 2-celled, 4-ovuled; style filiform; stigmas 2, ovate or oblong, flattened. Capsule subglobose, usually 1-celled. Seeds glabrous.

A small genus of 7 or 8 species, scattered through the warm and temperate regions of both hemispheres. Of the 4 New Zealand species 2 are found in most extra-tropical countries, one extends to Australia, and the remaining one to South America and the Island of Masafuera.

* Flowers large, 1–3 in. diam.
Leaves 2–5 in., oblong-sagittate, sinus at the base narrow, deep	1. C. sepium.
Leaves ½–1½ in., ovate-cordate or deltoid, membranous, sinus at the base broad, shallow	2. C. tuguriorum.
Stems short, prostrate. Leaves ½–2 in. across, broader than long, reniform, fleshy, sinus at the base broad, shallow	3. C. Soldanella.
** Flowers small, ½ in. diam.
Leaves sagittate, basal lobes narrow, acute, diverging	4. C. marginata.

1. C. sepium, R. Br. Prodr.]] 483.—Rhizome long, slender, extensively creeping underground. Stems slender, twining, 3–6 ft. long. Leaves alternate, variable in size and shape, 2–5 in. long, oblong-sagittate or hastate, acute or acuminate, rarely obtuse, cordate at the base with the lobes angular or truncate or rounded, membranous, glabrous or rarely slightly pubescent. Peduncles solitary, 1-flowered, angled or margined, often exceeding the leaves; bracts large, ovate or ovate-lanceolate, enclosing the calyx. Sepals subequal, ovate-lanceolate. Corolla large, 1½–3 in. diam., white or pink. Ovary incompletely 2-celled. Capsule ½ in. diam., globose, apiculate. Seeds smooth.—A. Cunn. Precur. n. 394; Raoul, Choix, 44; Hook. f. Fl. Nov. Zel. i. 183. Convolvulus sepium. Linn. Sp. Plant. 153; Hook. f. Handb. N.Z. Fl. 197.

Kermadec Islands, North and South Islands: Abundant in lowland situations as far south as Canterbury, apparently local in Otago. Pohue; Panahe; Bindweed. November–March.

Widely dispersed in most temperate countries, and everywhere highly variable.

2. C. tuguriorum, R. Br. ex Hook. f. Fl. Nov. Zel. i. 183, t. 47.—Stems slender, prostrate or climbing, often clothing shrubs or trees to a considerable height, glabrous or puberulous. Leaves ½–1½ in. long, broadly ovate-cordate or deltoid, acute or obtusely acuminate, entire or sinuate or angled, sinus at the base broad and shallow, glabrous, membranous. Peduncles usually longer than the leaves, terete or margined; bracts ovate-cordate or orbicular, apiculate, equalling the calyx and enclosing it. Sepals subequal, broadly ovate. Corolla large, 1–2 in. diam., white. Ovary incompletely 2-celled. Capsule ⅓ in. long, broadly ovoid, apiculate. Seeds yellowish-red.—Convolvulus tuguriorum, Forst. Prodr. n. 74; Hook. f. Handb. N.Z. Fl. 198. C. truncatella, Col. in Trans. N.Z. Inst. xxi. (1889) 95.

North and South Islands, Chatham Islands: Abundant from the Three Kings Islands and the North Cape to Foveaux Strait. December–February.

According to Sir J. D. Hooker, this is also found in Valdivia and Chiloe, and Mr. Hemsley (Bot. "Challenger" Exped.) has recorded it from the Island of Masafuera.

3. C. Soldanella, R. Br. Prodr. 483.—Rhizome long, creeping underground. Stems rather stout, 6–18 in. long, rarely more, prostrate and trailing, not twining, glabrous or puberulous. Leaves on petioles 1–3 in. long; blade ½–2 in. diam., usually broader than long, reniform or broadly rounded-cordate, obtuse or apiculate, entire or sinuate, thick and fleshy, sinus at the base broad and shallow. Peduncles solitary, 1-flowered, as long or longer than the leaves; bracts ovate-cordate, obtuse, rather shorter than the calyx. Sepals subequal, broadly ovate, obtuse. Corolla large, 1–1½ in. diam., pink or purplish. Ovary incompletely 2-celled. Capsule large, broadly ovoid, apiculate. Seeds blackish-brown.—A. Rich. Fl. Nouv. Zel. 200; A. Cunn. Precur. n. 395; Raoul, Choix, 44; Hook. f. Fl. Nov. Zel. i. 183. Convolvulus Soldanella, Linn. Sp. Plant. 159; Hook. f. Handb. N.Z. Fl. 198.

Kermadec Islands, North and South Islands, Stewart Island, Chatham Islands: Not uncommon on sandy shores throughout; inland on sandy beaches at Lake Taupo, &c. November–March.

Easily distinguished by the short uniformly prostrate stems, fleshy reniform leaves, and large black seeds. It is a common plant on maritime sands on almost all temperate shores.

4. C. marginata, R. Br. Prodr. 484.—Rhizome creeping; stems slender, twining, quite glabrous, 2–5 ft. long. Leaves on petioles 1–2 in. long; blade 1–3 in., sagittate, acute or acuminate, membranous; the basal lobes long, acute, diverging, often toothed or lobed. Peduncles usually shorter than the petioles, margined; bracts rounded-ovate, longer than the calyx. Sepals subequal, broadly ovate, obtuse. Corolla small, ½ in. diam., white. Ovary imperfectly 2-celled. Capsule globose; seeds usually 4.—Hook. f. Fl. Nov. Zel. i. 184, t. 48. Convolvulus marginatus. Spreng. Syst. i. 603; Hook. f. Handb. N.Z. Fl. 198; Benth. Fl. Austral. iv. 430.

North Island: Rare and local. Near Kaitaia, R. H. Matthews! between Mongonui and Whangaroa, T.F.C.; Whangarei and Owai, Colenso; Maungatapere, H. Carse! Paparoa, Omaha, and Thames, Kirk! Sea-level to 500 ft. December–March. Also in Eastern Australia.

3. CONVOLVULUS, Linn.

Herbs or undershrubs, erect or prostrate or climbing. Leaves entire or toothed or lobed. Peduncles axillary, 1- or many-flowered; bracts usually narrow or small. Sepals subequal or the inner narrower. Corolla campanulate; limb plaited, 5-angled or obscurely o-lobed. Stamens included; filaments filiform, dilated at the base; anthers oblong. Ovary 2-celled, 4-ovuled; style filiform; stigmas 2, distinct, oblong or linear. Capsule globose, 2-celled, 4-valved or splitting irregularly. Seeds glabrous.

A large genus of about 160 species, abundant in most subtropical or temperate countries, less plentiful in the tropics. The single New Zealand species is also found in Australia.

1. C. erubescens, Sims in Bot. Mag. t. 1067.—Perennial; usually more or less silky-pubescent, rarely almost glabrous. Root-stock stout, creeping; stems few or many, slender, prostrate and trailing, variable in length, 2–12 in. long or more. Leaves petiolate, very variable in size and shape; the lower ones with a blade ¼–¾ in. long, oblong-cordate or hastate, obtuse, quite entire or sinuate; in large specimens gradually passing into much narrower acute or acummate upper ones, with diverging entire or irregularly toothed basal auricles; in small specimens the narrow cauline leaves are often wanting. Peduncles as long as the leaves or nearly so, 1-flowered, with 2 subulate bracts some distance oelow the calyx. Sepals broadly oblong, obtuse, silky. Corolla variable in size, ⅓–¾ in. diam., white. Capsule ¼–⅓ in. diam., globose, 2-celled. Seeds 4, rough, brownish-black.—Hook. f. Fl. Nov. Zel. i. 185; Handb. N.Z. Fl. 198; Benth. Fl. Austral. iv. 429.

North Island: Hawke's Bay—Patangata, H. Tryon! Wellington— Palliser Bay, Colenso, Buchanan. South Island: Marlborough—Waihopai River, Munro; Kaikoura Mountains, Buchanan! Canterbury—Port Cooper, Lyall; Canterbury Plains, Armstrong! Kirk! Mackenzie Plains and Lake Tekapo, T.F.C. Otago—Not uncommon in the central and eastern districts, Buchanan! Petrie! Sea-level to 3000ft. December–March.

A remarkably variable little plant, closely allied to the common C. arvensis, L., of the Northern Hemisphere.

4. DICHONDRA, Forst.

Small prostrate or creeping perennial herbs. Leaves orbicular-cordate or reniform, entire. Flowers small, solitary, axillary. Sepals subequal, distinct to the base. Corolla broadly campanulate, deeply 5-lobed; lobes induplicate. Stamens shorter than the corolla; filaments filiform; anthers small. Ovary of 2 distinct lobes or carpels, each 1-celled with a basal style and 1 or 2 ovules. Capsules 2, membranous, erect, 1- or rarely 2-seeded, indehiscent or bursting irregularly.

A small genus of 4 or 5 species, widely spread in tropical and subtropical countries.

Leaves ¼–1 in. diam. Corolla shorter than the calyx or barely equalling it	1. D. repens.
Leaves ⅛–¼ in. diam. Corolla much longer than the calyx	2. D. brevifolia.

1. D. repens, Forst. Char. Gen. 39, t. 20.—A small silky-pubescent creeping herb; stems slender, 2–12 in. long, rooting at the nodes, branched, often forming broad matted patches. Leaves alternate or tufted at the nodes, usually on long petioles; blade ¼–1 in. diam., reniform, emarginate or rounded at the apex, silky on both surfaces. Peduncles as long or longer than the petioles. Flowers small, greenish-yellow, about ⅙ in. diam. Sepals obovate, silky. Corolla about equalling the sepals, rarely slightly longer. Capsules enclosed in the persistent calyx and shorter than it.—Forst. Prodr. n. 134: A. Rich. Fl. Nouv. Zel. 201; A. Cunn. Precur. n. 397; Raoul, Choix, 44; Hook. f. Fl. Nov. Zel. i. 185; Handb. N.Z. Fl. 199; Benth. Fl. Austral. iv. 438.

North and South Islands, Chatham Islands: Abundant from the North Cape to Otago. Sea-level to 2500 ft. Spring and early summer.

A widely spread plant in the tropical and subtropical districts of both hemispheres, extending northwards to the United States on one side and China on the other.

2. D. brevifolia, Buch. in Trans. N.Z. Inst. iii. (1871) 208.—Much smaller and more densely matted than D. repens, often formmg a compact turf. Leaves on short stout petioles; blade ⅛–¼ in. diam., orbicular-oblong or reniform, emarginate or rounded at the apex, cordate at the base, rather thick, silky on both surfaces or almost glabrous. Peduncles stout, erect, usually longer than the leaves. Flowers larger than in D. repens, ¼ in. diam., yellowish. Sepals obovate, silky. Corolla much longer than the sepals, sometimes twice as long. Ripe capsules about equalling the calyx.—D. repens var. brevifolia, Kirk in Trans. N.Z. Inst. x. app. xxxvii.

North and South Islands, Stewart Island: Not uncommon throughout, ascending to 3000 ft. November–January.

I retain this as a species with considerable hesitation, but it appears to constantly differ from reduced states of D. repens, which it otherwise much resembles, in the larger flowers with the corolla always much longer than the calyx.

5. CUSCUTA, Linn.

Leafless usually annual herbs, germinating in the soil but not rooting in it, producing filiform branched stems which twine round herbs or shrubs and become parasitic by means of suckers which penetrate the bark, the lower portion of the stem then dying away. Flowers small, usually whitish, in dense or open cymose fascicles, sessile or shortly pedicelled. Sepals 5 or 4, distinct or connate at the base. Corolla campanulate or urceolate or ovoid; lobes 5–4, short, imbricate in the bud. Stamens 5–4, inserted on the throat of the corolla, above a ring of many scale-like lacerate appendages. Ovary globose, 2-celled, 4-ovuled; styles 1 or 2, persistent; stigmas capitate or filiform. Capsule 1–4-seeded, membranous, dry or succulent, circumscissile or bursting irregularly. Seeds glabrous, albuminous; embryo long and slender, spirally coiled; cotyledons wanting or obscure.

A very remarkable genus, comprising about 90 species, spread through most tropical and temperate countries. Some of them, such as the clover dodder, C. epithymum var. trifolii, are dangerous pests to cultivated crops. The single New Zealand species is very imperfectly known, and may not be truly indigenous.

1. C. densiflora, Hook. f. Fl. Nov. Zel. i. 186.—Stems slender, densely matted and twisting together, as thick as stout thread. Flowers crowded in short densely congested 6–10-flowered racemes ¼–½ in. long. Calyx shortly 5-lobed; lobes oblong, obtuse. Corolla ⅛ in. long, subcampanulate, marked with transparent oil-glands; lobes 5, short, rounded, recurved. Scales broadly oblong, obtuse, fimbriated, united at their bases by a thin membrane. Filaments longer than the anthers. Styles 2, rather long; stigmas capitate.—Handb. N.Z. Fl. 199.

South Island: Marlborough—Port Underwood, Lyall.

I have seen no specimens of this, and the above diagnosis has been drawn up from those given by Hooker in the Flora and the Handbook. According to Hooker, Dr. Engelmann, who examined the type at Kew, reported that it hardly differs from the South American C. racemosa, Martius, a species which was introduced into Europe many years ago, and caused much damage to crops of lucerne. It subsequently appeared in fields of lucerne in California. Mr. Kirk (Trans. N.Z. Inst. xx. 182) records the occurrence of the same plant (under the synonym of C. hassiaca, Pfeiff.) in lucerne-fields in Canterbury, but there are no specimens in his herbarium.

C. novæ-zealandiæ, T. Kirk in Trans. N.Z. Inst. xx. (1889) 183 (name only).—After a careful examination of the type specimens in Mr. Kirk's herbarium, I have no hesitation in referring this to the northern C. epithymum, Linn., which has been observed in many localities in the colony, and which often associates itself with the indigenous vegetation.