| Name | Antithamnion cruciatum var. radicans (J. Agardh) Collins | 
| Authorship | (J. Agardh) Collins | 
| Rank | Variety | 
| Placed in | Antithamnion cruciatum (C. Agardh) Nägeli | 
| Holdings | 2 Specimens held in the Harvard University Herbaria identified as Antithamnion cruciatum var. radicans (J. Agardh) Collins | 
| Identification made in | [no date] (2) |