Ottelia

The genus is highly variable, with a variety of features. It contains aquatic herbs with crowded leaves. Some of the leaves are held on short stems. Others float on long stems. The rooting stem is long. The flowers are held in a herbaceous bract that is many nerved and has two to six clear ribs. The tubular spathe is shortly divided into two. • Subgenus Ottelia has bisexual flowers. • Section Ottelia: The spathes have a single flower and six to nine carpels in the ovary. • Section Oligolobos: The spathes have many flowers and an ovary with three carpels. • Subgenus Boottia has unisexual flowers. The male spathes have one to many flowers while the female spathes always have many flowers. • Section Boottia: The males spathes have one flower and the ovaries of the female flowers have nine to fifteen carpels. • Section Xystrolobos: The female spathes have two to many flowers and an ovary with three or nine carpels. == Distribution ==

This genus is found throughout the Paleotropics, from Africa to Asia to Australia and New Caledonia and to Brazil. == Phylogenomics and evolution ==

Originating in the mid Miocene, this genus now consists of two major clades that correspond to the two major centers of diversity - Africa and Asia. Morphological evidence suggests that this genus originated in Africa. It then spread to South America and Australasia via the ocean, and then from Australasia to Asia. Global cooling, the development of the East Asian monsoon climate and tectonic movement likely aided diversification in China. The movement of the Yunnan-Guizhou Plateau Pin the liocenehas been suggested to explain the high endemism of Chinese species of Ottelia. == Species ==

This genus is the second largest in its family (Hydrocharitaceae). == Conservation ==

The species belonging to this genus are being increasingly negatively impacted by the use and pollution of their water bodies. They have also been declining as a result of climate change. This will continue to occur as climate change accelerates habitat fragmentation and habitat loss due to changing conditions, including increasing water temperatures. ==Gallery==

Ottelia alismoides - flower view.jpg| Flower of Ottelia alismoides ==References==