Position in a system
| system | Vitae - living organisms |
| domain | Eukaryota Whittaker & Margulis, 1978 - lifeforms with nucletic cells |
| superregnum | Bikonta - bikonts |
| Corticata | |
| Archaeplastida | |
| phylum | Rhodophyta Wettst - red algae |
| subphylum | Rhodophytina |
| class | Florideophyceae Cronquist |
| subclass | Rhodymeniophycidae |
| order | Ceramiales Nägeli |
| family | Rhodomelaceae Horaninow |
| genus | Alsidium C.Agardh |
| species | Alsidium seaforthii (Turner) J.Agardh |