Global description
Antigonon leptopus is a branched woody vivacious plant that climbs the surrounding vegetation by clinging their axillary tendrils to leaves and terminal inflorescences. It reaches up to 10 m long. It produces underground tubers which allows it to propagate vegetatively. The stalked leaves are alternate, simple, heart-shaped, with tapered pointed end, and full margin, glabrous to more or less pubescent. The ocrea is underdeveloped. The flowers, which are usually bright pink, are arranged, isolated or in small groups on the raceme axillary to the leaves of the terminal part. The fruit is a conical achene or trigonal with glossy surface of brown color.
General habit
Vivacious woody branched vine clinging by axillary tendrils, reaching 6 to 10 m long.
Underground system
The plant has a taproot system. It produces underground ellipsoid shaped tubers.
Stem
The slender stem climbs or spreads on the surrounding vegetation with the tendrils at the base of the leaves. It is branched in angular sections, glabrous or pubescent. Older stems become woody and sometimes brown at the base. Young stems are reddish brown or green. The twigs are slender, the pubescence ranging from sparse to dense, and cottony in appearance.
Leaf
The leaves are alternate and simple. The petiole (0.7 to 3 cm long), with the base slightly clasping the stem, is covered with cottony hairs. It has at its base a very short ocrea (0.2 to 2 mm long). The lamina, with smooth margin, is oval to triangular with a heart shaped base, the apex pointed to acuminate, ending with a small mucro. The blade is 2.5 to 15 cm long and 2 to 12 cm wide. The ribs are pressed on the upper face, protruding on the underside. The main veins, arcuate, are joined together by transverse secondary veins forming a second reticle. The lamina may be glabrous or hairy, especially on the veins of the lower face. The lower leaves are usually larger and wider, the upper leaves are smaller and narrower.
Inflorescence
The flowers are borne on slender branches, 3 to 20 cm long, branched or not, axillary of the upper leaves. These branches are extended by a tendril. The flowers are isolated or grouped by 2 to 4, along the branch.
Flower
The pedicel of the flowers (3-10 mm long), glabrescent to cottony pubescent, is hinged to the middle. Petals and sepals are membranous to reticulately veined, pink or red in color, sometimes white. The 3 external, 7 to 9 mm long, deeply cordate at the base, are slightly longer than the internals. They increase in size after fertilization, reaching 15 to 17 mm long and 4 to 19 mm wide. The 8 stamens have short pedunculated glands. The superior ovary is crowned by three stigmas and styles.
Fruit
The fruit is a conical, trigonal achene, 8 to 12 mm long and 4 to 7 mm wide, brown in color, and shiny surface. It remains enclose in the perianth.
