Kadua
| Kadua | |
|---|---|
| Kadua affinis | |
| Scientific classification | |
| Kingdom: | Plantae | 
| Clade: | Tracheophytes | 
| Clade: | Angiosperms | 
| Clade: | Eudicots | 
| Clade: | Asterids | 
| Order: | Gentianales | 
| Family: | Rubiaceae | 
| Subfamily: | Rubioideae | 
| Tribe: | Spermacoceae | 
| Genus: | Kadua Cham. & Schltdl.  | 
| Type species | |
| Kadua acuminata Cham. & Schltdl.  | |
| Species | |
| 
 ~ 29 species, see text  | |
Kadua is a genus of flowering plants in the family Rubiaceae. It comprises 29 species, all restricted to Polynesia. Twenty-two of these are endemic to the Hawaiian Islands. Some of the species are common at high elevation. Others are single-island endemics or very rare, and a few are probably extinct. Kadua affinis is widely distributed in Hawaii and is polymorphic. The type species for the genus is Kadua acuminata.
Kadua was formerly included in a broadly defined and polyphyletic Hedyotis, which encompassed, in addition to Kadua, species now placed in Oldenlandia, Oldenlandiopsis, Houstonia, and other genera. Hedyotis is now circumscribed more narrowly.