Ipomoea (PROSEA Auxiliary plants)

Plant Resources of South-East Asia Introduction

List of species

Ipomoea L.

Protologue: Sp. pl.: 159 (1753).

Family: Convolvulaceae

Chromosome number: x= 15; I. littoralis: 2n= 30, 60; I. pes-caprae: 2n= 30, 22-31

Major species and synonyms

• Ipomoea imperati (Vahl) Griseb., Cat. pl. Cub.: 203 (1866), synonyms: Convolvulus sinuatus Petagna (1787), Ipomoea stolonifera (Cirillo) J.F. Gmelin (1791), I. carnosa R. Br. (1810).

• Ipomoea littoralis Blume, Bijdr.: 713 (1825), synonym: I. denticulata (Desr.) Choisy (1834).

• Ipomoea pes-caprae (L.) R. Br., Tuckey, Narr. exped. Zaire: 477 (1818), synonyms: Convolvulus pes-caprae L. (1753), Ipomoea biloba Forsk. (1775), I. maritima (Desr.) R. Br. (1810).

Vernacular names

General:

• ipomoea (En).

I. imperati:

• Little horse's foot print, white-flower beach morning glory (En)
• Indonesia: klemut, kangkungan (general), krangkungan (Javanese)
• Thailand: phakbung-thale (central).

I. littoralis:

• Little horse's foot-print (En)
• Indonesia: akar hitang (Palembang), kangkung laut (Bangka), loboke ma loha (Halmahera)
• Malaysia: kangkong, tapak kuda kecil (Peninsular)
• Philippines: bulukan (Tagalog), malakamote (Ibanag), panggi-panggi (Sulu)
• Thailand: chingcho lek (Peninsular).

I. pes-caprae:

• Beach morning glory, horse's foot-print, goat's foot creeper (En)
• Bay-hops (Am)
• Indonesia: daun katang, tapak kuda (general), katang-katang (Bali)
• Burma (Myanmar): pinlaikazum
• Cambodia: trakuon kantek, pak bung tale
• Thailand: phakbung-thale (central)
• Vietnam: rau muống biển.

Origin and geographic distribution

Ipomoea comprises about 500 species occurring throughout the tropics and subtropics, the majority in America and Africa. I. imperati is pantropical, rather rare in Malesia, but occurring in Peninsular Malaysia, Madura and the Philippines, I. littoralis is confined to the tropics of Asia, Australia and the western Pacific, I. pes-caprae is one of the most common beach plants throughout the tropics, including South-East Asia.

Uses

The species treated here live on sandy beaches and act as sand binders by checking erosion and drifting of sand in wind-swept areas. They contribute to the accretion of land and facilitate the establishment of other plants. I. pes-caprae has been used successfully to revegetate mine spoil. Its seeds are used as a remedy for stomach-ache and cramp. In East Malaysia the leaves are made into poultices and applied to ulcers, swellings and wounds, and also against rheumatism. In Kambangan Island, south of Central Java, and in Thailand, the juice from the stem is used to treat the sting of jellyfish and toadfish, elsewhere it is taken as a diuretic. The leaves are given as a fodder to pigs, but if eaten by dairy cows their milk is spoiled. Young leaves of I. imperati are eaten as a vegetable by the Madurese, while those of I. littoralis were eaten in times of famine in the Pacific. Flowers of the latter are used in garlands.

Properties

The seed of the three Ipomoea spp. contain glycoside resins. An aqueous extract of the stems and leaves reversibly counteracts the spasmodic effects of the poison of jellyfish.

Description

• Herbs or shrubs, usually twining, sometimes prostrate, floating or erect.
• Leaves mostly with petiole, alternate, variable in shape and size, entire, lobed or divided.
• Inflorescence mostly in axillary, one to many-flowered dichasia.
• Flowers small to large; sepals 5, herbaceous or coriaceous, persistent, often somewhat enlarged in fruit; corolla regular, usually funnel-shaped or campanulate; limb 5-lobed; mid-petaline bands well-defined by 2 distinct veins; stamens 5, inserted near base of corolla tube, not exserting the corolla, filaments often unequal in length; ovary 2(-4)-locular, with 4(-6) ovules; style 1, simple, filiform, not exserting the corolla.
• Fruit a globose or ovoid capsule, 4(-6)-valved, 4(-6)-seeded.

I. imperati

• Perennial, glabrous vine. Stem trailing, rooting at the nodes, terete, up to 5 m long.
• Leaves fleshy, very variable in shape, even on the same plant; petiole 0.5-4 cm long; blade linear, lanceolate, ovate or oblong, 1.5-4(-8) cm × 1-3(-5) cm, margin entire or undulate, base truncate, obtuse or cordate, apex obtuse to emarginate or 2-lobed; blade sometimes 3-7-lobed.
• Inflorescence axillary, 1(-3)-flowered; peduncle 12-15 mm long; pedicel 8-15 mm long, in fruit up to 25 mm; bracts minute, linear, 2-3 mm long.
• Sepals oblong, unequal, inner ones 10-15 mm long, outer ones shorter, acute or obtuse, mucronulate, glabrous, subcoriaceous; corolla funnel-shaped, 3.5-5 cm long, glabrous, white, pale yellow inside with a purple centre; filaments hairy at base.
• Capsule globular, about 1 cm long, smooth, 2-celled, 4-valved, up to 4-seeded.
• Seed trigonous-rounded, 5-9 mm long, short-tomentose, with longer hairs along edges, light brown.

I. littoralis

• Perennial vine. Stem prostrate and rooting at the nodes or twining, thin, slender, herbaceous, glabrous, or sometimes sparsely pubescent, woody at the base with age.
• Leaves coriaceous, glabrous; petiole 0.5-7 cm long; blade broadly ovate to oblong in outline, occasionally orbicular to reniform, 1-10 cm × 1-8 cm, base cordate, apex acute to obtuse, rarely retuse, margin entire, undulate, angular or 3(-7)-lobed.
• Inflorescence axillary, 1-few-flowered; peduncle 1-9 cm long; pedicel 1-4 cm long; bracts 1-2 mm long.
• Sepals unequal, 2 outer sepals oblong-elliptical to elliptical-ovate, coriaceous, 6-10 mm long, apex acute to obtuse, mucronulate, 3 inner sepals thinner, with membranous margins, suborbicular to sometimes elliptical, 8-12 mm long; corolla funnel-shaped, 3-4.5 cm long, lavender to pinkish-purple, with a darker centre; stamens unequal, filaments 6-12 mm long, hairy at base.
• Capsule depressed globose, about 1 cm in diameter, 4-seeded, sometimes fewer.
• Seed suborbicular with a notch, 3.5-4 mm long, glabrous, black or dark brown.

I. pes-caprae

• Perennial, glabrous vine with thick taproot. Stem prostrate, sometimes twining, 5-30 m long, often rooting at the nodes.
• Leaves often pointing to one side only; petiole up to 17 cm long; blade variable, ovate, elliptical, circular, reniform, nearly square or oblong, 3.5-10 cm × 3-10 cm, rather thick, with 2 abaxial glands at base of midrib, base broadly cuneate, truncate, or shallowly cordate, margin entire, apex emarginate or deeply 2-lobed, mucronulate.
• Inflorescence 1-several-flowered; peduncle stout, 3-16 cm long; bracts early caducous, broadly triangular, 3-3.5 mm long; pedicel 1-7 cm long.
• Sepals unequal, somewhat leathery, glabrous, apex obtuse, mucronulate, 2 outer ones ovate-elliptical, 5-9 mm long, 3 inner ones nearly circular and concave, 7-13 mm long; corolla funnel-shaped, 3-6.5 cm long, purple to reddish-purple, with darker inside centre; filaments 7-12 mm long, hairy at base.
• Capsule globular, 1-1.7 cm in diameter, glabrous, leathery.
• Seeds 4, trigonous-globose, 6-10 mm long, black, densely brownish tomentose.

Growth and development

I. pes-caprae is self-incompatible, which is controlled by several genes.

Other botanical information

I. imperati is better known as I. stolonifera. The nomenclature of this taxon is complicated. The oldest valid name is Convolvulus sinuatus Petagna (1787) with Convolvulus stolonifer Cirillo (1788) as homotypic synonym and Convolvulus imperati Vahl (1790) as oldest heterotypic synonym. After being transferred to the genus Ipomoea, the combination I. sinuata was not allowed, because this name had been given to a different species in 1798 by Ortega. The combination I. stolonifer is not permissible because its basionym is an illegitimate name; hence I. imperati is the correct name.

I. littoralis Blume used to be considered to be identical to I. gracilis R. Br. The latter, however, is a distinct species; it is quite rare and confined to the northern coast of Australia.

In I. pes-caprae, 2 subspecies are recognized: subsp. brasiliensis (L.) Ooststroom (leaf apex emarginate or truncate; leaf base truncate, rounded, attenuate to slightly cordate; outer sepals 5-8 mm, inner ones 7-11 mm long; corolla 3-5 cm long; pantropical, and the most common form in South-East Asia) and subsp. pes-caprae (leaf apex deeply lobed with rounded lobes, leaf base cuneate to attenuate; outer sepals 9 mm, inner ones 13 mm long; corolla 6.5 cm long; occurring in Arabia and tropical Asia).

Ecology

The sand-binding Ipomoea species form a characteristic component of the "pes-caprae" communities on tropical beaches. They usually grow in association with Canavalia maritima (Aubl.) Thouars and salt-tolerant grasses and sedges. I. pes-caprae also occurs inland, along roadsides and ditches, up to 800 m altitude.

Although these Ipomoea species grow on the beach, they depend on ground water with a lower salt content than sea water. They are tolerant of high temperature, periodic drought, sea water spray, high soil pH and low soil nitrogen content.

Propagation

Natural propagation of sand-binding Ipomoea species is by seed. The capsules float and are probably dispersed by sea currents. When planted for erosion control, stem cuttings are used, placed 60-100 cm apart, in rows perpendicular to the prevailing wind.

Husbandry

The "pes-caprae" formation may form a complete soil cover that traps leaf litter and wind-blown organic material, thus accumulating organic matter and improving soil fertility. Analysis of a beach soil in Sulawesi indicated per 100 g dry soil: C 0.2 g, N 0.03 g, P 3.3 ppm at the edge of the sea, and at a distance of 8 m from the sea: C 1.1 g, N 0.13 g, P 18.6 ppm.

Genetic resources

A small number of accessions of I. littoralis and I. pes-caprae are maintained at the Southern Regional Plant Introduction Station, Griffin, Georgia, United States.

Breeding

I. littoralis is one of the likely progenitors of I. batatas (L.) Lamk, the sweet potato, and is used in experimental breeding programmes.

Prospects

Most sand-binding Ipomoea species grow spontaneously on beaches. With more intensive utilization of beaches and the agricultural hinterland, planting may become more important. There is an urgent need for selection of good planting material and research into cropping methods. The species' usefulness for reclamation of mine spoils also needs further investigation.

Literature

• Austin, D.F., Jarret, R.L. & Johnson, R.W., 1993. Ipomoea gracilis R. Brown (Convolvulaceae) and its allies. Bulletin of the Torrey Botanical Club 120: 49-59.
• Austin, D.J. & Huáman, Z., 1996. A synopsis of Ipomoea (Convolvulaceae) in the Americas. Taxon 45: 3-38.
• Craig, R.M., 1977. Herbaceous plants for coastal dune areas. Proceedings of the Florida State Horticultural Society 90: 108-110.
• La Valva, V. & Sabato, S., 1983. Nomenclature and typification of Ipomoea imperati (Convolvulaceae). Taxon 32: 110-114.
• Martinick, W.G. & Atkins, K., 1992. Establishment and management of vegetation on mine waste and land adversely affected by iron ore mining operations in the Pilbara. In: Fox, J.E.D. (Editor): Rehabilitation of mined lands in Western Australia. Western Australian Institute of Technology, Bentley, Australia. pp. 69-75.
• Pongprayoon, U., Bohlin, L. & Wasuwat, S., 1991. Neutralization of toxic effects of different crude jellyfish venoms by an extract of Ipomoea pes-caprae (L.) Br. Journal of Ethnopharmacology 35: 65-70.
• van Ooststroom, S.J., 1953. Convolvulaceae. In: van Steenis, C.G.G.J. (Editor): Flora Malesiana, Series 1, Vol. 4. Noordhoff-Kolff, Djakarta, Indonesia. pp. 458-488.
• Venkatesan, A., Venkatesalu, V. & Chellapan, K.P., 1995. Photosynthetic characteristics of Ipomoea pescaprae Forsk. under NaCl stress. Photosynthetica 31: 631-634.
• Wong, P.P., 1978. The herbaceous formation and its geomorphic role in East Malaysia. Malayan Nature Journal 32: 129-141.

Authors

• B. Sunarno & L.P.A. Oyen