Botany of Gongronema latifolium

Gongronema latifolium belongs to the family Asclepiadaceae and genus Gongronema with up to 70 species. Gongronema latifolium is commonly called ‘utazi’ in south eastern Nigeria and ‘arokeke’ in south western Nigeria (Eleyinmi, 2008) [17]. It is found mainly in the tropics and subtropical regions of Africa, Asia and Oceania (Dutta, 2005) [12]. It is a climbing and twining shrub and the mode of propagation is mainly by stem cuttings and by seeds. Leaf blade is broadly ovate to almost circular. Leaves are simple, opposite, decussate, occasionally whorled, peltate and usually have no stipules. Leaf margin is entire, venation is palmate and the leaf base is deeply cordate. Leaf is glabrous with acute to acuminate apex. Length is between 7.0-8.5cm and width is between 4.0-6.5cm (Osuagwu, et al., 2013) [42]. The adventitious roots arise from the nodes when the stem makes contact with the soil. Inflorescence is a cymose panicle up to 13 cm long. Flowers are bisexual, actinomorphic, pale yellow and fragrant, pedicel is 2-4 mm long. Calyx has five basal glands with elliptical to rounded lobes. Corolla is tubular, about 5 mm long with five triangular to ovate lobes and five scale-like corona inserted at the base of gynostegium. There are five stamens and the filaments form a tube. Anthers are erect with membranous apical appendages. Ovary is superior, the styles are short and the stigma heads are conical in shape. Fruit is a follicle that is oblonglanceolate and splits open lengthwise along the seam to release seeds. The fruit is green initially, turning to brown and finally black at maturity. Fruit development takes several months from April to November and dehisces between (December-February). New flowers start to appear between January and March and often meet old fruits. Seeds are flat and attached to a white silky tuft to aid dispersal. The seeds are coma shaped and measure about 0.5 cm in length (Mosango 2011; Osuagwu et al., 2013) [34, 42]. Mature seeds planted within two weeks after harvest take seven to fourteen days at temperature of about 27 oC and have germination rate of 67%.

Ethnobotanical uses

Gongronema latifolium is used by folk people in the treatment of various diseases. The twigs and branches are used for cleaning the teeth (chewing stick), in the treatment of cough, diabetes, hypertension and malaria (Etetim et al., 2008) [20]. They reported that the extract or cold infusion of the pounded leafy branches together with lime juice, expels intestinal worms, dispels stomach upset and serves as blood tonic. The leaf juice mixed with pineapple and lime juice is used in the treatment of typhoid fever (Etetim et al., 2008) [20]. In Imo state of Nigeria, G. latifolium leaves are used as vegetables for preparation of pepper soup, yam stew and used with other spices to prepare soup usually given to a woman after child delivery and to treat stomach ache (Uzodimma 2013) [48]. An infusion of the aerial parts is taken to treat cough, intestinal worms, dysentery, dyspepsia and malaria (Akuodor et al., 2010; Mosango 2011) [34]. It is also taken to restore loss of appetite. In Sierra Leone, an infusion or decoction of the stem with lime juice is taken as a purgative to treat colic and stomach-ache (Mosango, 2011) [34]. The latex is applied to teeth affected by caries. Asthmatic patients use fresh leaves to