Frank Hann National Park was declared to protect sand plain habitat and heath flora. The park was named after surveyor and explorer Frank Hann, who traversed the area in 1901.
There are no facilities or developed visitor sites in this park, but people can still enjoy the drive through it along the Lake King-Norseman Road. Spring and early summer (September through to January) is the best time for a visit, but something is in flower all year round.
On the deeper sandy soil, mallees are the dominant plants, forming an open upper canopy, over several layers of shrubs, and annuals such as everlastings during good seasons. Snap and rattle (Eucalyptus gracilis), tall sand mallee (Eucalyptus eremophila), capped mallee (Eucalyptus pileata), Fremantle mallee (Eucalyptus foecunda) and the mallee form of red morrell (Eucalyptus longicornis) are common.
Four different banksia species can be recognised in shrubby areas. Swordfish banksia (Banksia elderiana) is a large, scruffy shrub whose golden flowers, produced in summer, hang downwards from the branches. Another golden-flowered banksia, flowering a little earlier, is cannonball banksia (Banksialemanniana). It is a sparser, upright bush, with solid, spherical fruits. Southern plains banksia (Banksia media) forms a large, rounded shrub with prominent yellow flower-spikes in autumn through to winter. Violet banksia (Banksia violacea) is much smaller, with needle-shaped leaves and small violet flowers in early summer.
Wattles, sheoaks and melaleucas, such as broom bush (Melaleuca uncinata), tend to be the dominant plants in areas of thicket, with diverse but sparse layers of shorter shrubs beneath them. The ground layer often includes everlastings and orchids.
Featherflowers are a colourful part of the heathland vegetation. A yellow featherflower (Verticordia chrysantha), the painted featherflower (Verticordia picta) which is pink, the rapier featherflower (Verticordia mitchelliana) which is red, and the extraordinary bush cauliflower (Verticordia eriocephala) - whose small, crowded white flower heads look, from a distance, exactly like that vegetable - are among those found in the park.