Plants of this species of forget-me-not are perennial rosettes with ebracteate inflorescences and white corollas with exserted stamens.

[3][4] Ferdinand von Mueller finally made the valid combination M. exarrhena in 1889 in the updated Systematic Census of Australian Plants.

[1]The lectotype (K001094009) and the isolectotype (K001094010) of Exarrhena suaveolens are on the same sheet at Kew Herbarium,[5] and were designated by Peter G. Wilson & Jeannie Highet.

[6] The species epithet exarrhena is based on the Greek word arrhen and refers to the exerted anthers.

Both surfaces of the leaf are uniformly and densely covered in flexuous to curved, usually appressed, antrorse (forward-facing) hairs that are oriented parallel to the midrib.

Each rosette has multiple ascending, branched ebracteate inflorescences that are bifurcating at the top and up to 470 mm long.

The calyx is 2–5 mm long at flowering and 3–6 mm long at fruiting, lobed to half to two-thirds of its length, and densely covered in straight to flexuous, often hooked, patent to erect, mostly antrorse hairs (with some retrorse or backward-facing hairs near the base).

[3] On the basis of morphological data, Myosotis exarrhena may hybridise with M. australis where the two species are known to co-occur in New South Wales, ACT and Victoria.