| Willea | |
|---|---|
 | |
| Willea rectangularis | |
Scientific classification  | |
| Domain: | Eukaryota |
| Supergroup: | Archaeplastida |
| Clade: | Viridiplantae |
| Division: | Chlorophyta |
| Class: | Trebouxiophyceae |
| Order: | Chlorellales |
| Family: | Oocystaceae |
| Genus: | Willea Schmidle |
| Species | |
Westella is a genus of green algae in the family Oocystaceae. It is found in freshwater habitats such as ponds and lakes, as part of the phytoplankton. It has a cosmopolitan distribution.
Willea consists of four-celled (rarely two-celled) colonies (termed coenobia); the coenobia may be aggregated to form compound colonies of 100 cells or more, arranged in a single plane. The cells are oval to cylindrical, arranged in a rectangle forming a rhomboidal gap. The cell walls are smooth. Cells are uninucleate, and contain a single parietal chloroplast; the chloroplast has a pyrenoid but this may be difficult to observe. Asexual reproduction occurs by the formation of autospores, which are organized into coenobia; they enlarge with the cell wall, which eventually dissolves, releasing the new cells. Sexual reproduction and flagellated stages are not known in this genus.
A number of species formerly included in the genus Crucigeniella are now placed in Willea; the name Crucigeniella is illegitimate.
