The axodines are a group of unicellular stramenopiles that includes silicoflagellate and rhizochromulinid algae, actinomonad heterotrophic flagellates and actinophryid heliozoa.

[5] The Axodine grouping was unusual in breaking with the traditions of botanical and protozoological taxonomy to include the actinophryid heliozoa as part of the lineage that also contained the pedinellid algae along with colorless relatives such as Actinomonas, Pteridomonas, and Ciliophrys; the axodines further included the silicoflagellates, and Rhizochromulinales.

[6][7][8] The name points to a character that is deemed to be synapomorphic for the group: that is the microtubular arrays that extend from the surface of the nucleus.

Many flagellated forms have a single emergent flagellum, that lacks the root structure found in related chrysophytes.

In addition to the silicoflagellates and actinodines, the marine amoeboid Rhizochromulina marina is included here based on the structure of its zoospores.