Pentodon pentandrus (Schumach. & Thonn.) Vatke

Global description

Pentodon pentandrus is an herbaceous plant spread and upright at the ends, diffuse, with succulent stem, up to 1 m in length. It is an entirely hairless plant except for some hairs in the corolla. Leaves are simple, opposite, sessile, linear lanceolate, margin entire with a stipular collar around the stem. The inflorescence is an axillary panicle. The flowers are small, long pedicelled. They are composed of a calyx with 5 welded sepals and a corolla in tube prolonged by 5 lobes with bristles erected inside the petals and on the throat. Their color varies from greenish to white, blue and purple. The fruit is a dehiscent capsule that contains many small angular seeds. It is turned towards the ground at maturity.

General habit

Annual in cultivation to shortly perennial in the wild, somewhat fleshy, diffuse with stems rooted at nodes and often upright at the ends. It reaches 50 cm to 1 m long.

Underground system

The root is a taproot.

Stem

The stem is weak and soft, succulent, of round section to weakly polygonal, little branched, shiny and glabrous. It is often a little tinged with purple.

Leaf

The leaves are simple, opposite decussate and sessile. They are connected around the stem by a glabrous and short stipular collar, prolonged by 2 to 4 narrow divisions of 0.5 to 2.5 mm long. The blade is succulent, glabrous on both sides, narrowly lanceolate to elliptical, pale green in color. It is 1.5 to 8 cm long and 0.5 to 2.5 cm wide. Its base is rounded to wedge-shaped. It ends in a more or less acute corner. The margin is smooth. The lateral veins are not very visible.

Inflorescence

The inflorescence, pedunculate, is a set of pauciflorous cymes arranged along a rachis with  angled nodes. It measures 6 to 17 cm long, 1 to 7 cm for the peduncle. It is composed of 6 to 13 pedicelled flowers.

Flower

The pedicel is 2 to 15 mm long. The calyx is composed of 5 welded sepals, glabrous, extended with 5 triangular teeth. The corolla is formed of a tube 2 to 4.5 mm long and 5 triangular-oval lobes 1 to 3 mm. It measures 3 to 6 mm in diameter. She is glabrous on the outside. She wears long hairs erect on the inside of the petals and hair in the throat, which are very visible. It can be white, greenish, blue or purple. Stamens are free. They are inserted at the base of the corolla.

Fruit

The fruit is a dehiscent capsule ending in a beak. It is 2.5 to 4.5 mm long and 2.8 to 3.5 mm in diameter. At maturity, it is directed towards the ground. It contains many small seeds (around 140).

Seed

The seed is ovoid angular, black in color at maturity. It is 0.2 mm long.

Origin

Pentodon pentandrus is native to Africa and Indian Ocean islands.

Worldwide distribution

It is widespread in Africa from Mauritania and Senegal to Sudan, Ethiopia and Somalia, southern Namibia, South Africa, Swaziland to Zimbabwe, and Madagascar; it is also present in Arabia in Yemen. She is present in Seychelles. It has been introduced in the USA, Cuba, Nicaragua and Brazil.

https://www.gbif.org/species/5340516