Morrenia

Morrenia is a genus of flowering plants in the family Apocynaceae, subfamily Asclepiadoideae (formerly the family Asclepiadaceae). These plants are typically twining vines or herbaceous climbers, native to South America, particularly Argentina, Brazil, Paraguay, and Uruguay.

Morrenia species are characterized by their latex-containing stems, opposite leaves, and intricate flower structures. The flowers are usually small and often have a complex pollination mechanism involving insects. The fruits are typically follicles containing seeds with a coma (a tuft of hairs), which aids in wind dispersal.

Several species within the Morrenia genus are considered weeds, particularly in agricultural areas, due to their vigorous growth and ability to climb and smother other plants. Morrenia odorata (commonly known as "Diplocalyx odoratus" or "vine-milkweed") is a notable example, known for its fragrant flowers and invasive tendencies in some regions. Its ability to reproduce both sexually (via seeds) and vegetatively (via rhizomes) contributes to its persistence and spread.

The classification of Morrenia has undergone revisions over time, and its relationship to other genera within the Asclepiadoideae remains an area of ongoing research.