Zygnematophyceae

Zygnematophyceae (or Conjugatophyceae) is a class of green algae in the division Charophyta, consisting of more than 4000 described species. It contains the order Zygnematales. The Desmidiales emerged within the Zygnematales. The Zygnematophyceae are the sister clade of the Mesotaenium, together forming the sister clade of the land plants. The body plan of Zygnematophyceae is simple, and appear to have gone through a secondary loss of morphological complexity. They contain genes involved in protection from desiccation that appear to have been derived by horizontal gene transfer from bacteria; the genes are found in plants, Zygnematophyceae, bacteria, but no other organisms. The genes may have helped to enable plants to make the transition to life on land.
Sexual reproduction in the Zygnematophyceae takes place through a process called "conjugation". Here cells or filaments of opposite gender line up, and tubes form between corresponding cells. The male cells then become amoeboid and crawl across the female, or sometimes both cells crawl into the connecting tube. The cells then meet and fuse to form a zygote, which later undergoes meiosis to produce new cells or filaments. As in plants, only the female passes its chloroplasts on to the offspring.
Taxonomy.
Class Zygnematophyceae
Phylogeny