| Cystocloniaceae Kütz., 1843 |
| Cystoclonium Kütz., 1843 |
| Cystoclonium purpureum (Hudson) Batters, 1902 |
| Hypnea J.V. Lamour., 1813 |
| Hypnea alopecuroides Kütz., 1868 |
| Hypnea californica Kylin, 1941 |
| Hypnea cervicornis J. Agardh, 1851 |
| Hypnea cornuta (Kütz.) J. Agardh, 1851 |
| Hypnea divaricata (C. Agardh) Grev., 1830 |
| Hypnea esperi Bory, 1828 |
| Hypnea evermannii Setch. & N.L. Gardner, 1930 |
| Hypnea johnstonii Setch. & N.L. Gardner, 1924 |
| Hypnea musciformis (Wulfen) J.V. Lamour., 1813 |
| Hypnea nidifica J. Agardh, 1851 |
| Hypnea nidulans Setch., 1924 |
| Hypnea pannosa J. Agardh, 1847 |
| Hypnea spicifera (Suhr) Harv., 1847 |
| Hypnea spinella (C. Agardh) Kütz., 1847 |
| Hypnea valentiae (Turner) Mont., 1841 |
| Hypnea valentiae var. gardneri Hollenberg, 1972 |