Grasslands have thin soils, low productivity and usually some southern exposure, or are successional stages between open sand and coastal forest. These extreme habitats may be too dry in summer to support shrubs and trees, and are often sites of high diversity. Higher elevation grasslands are relicts of habitats that were much more common during ice ages. The balds and associated rocky slopes of peaks in Clatsop County, Oregon, contain around two hundred species of grasses and wildflowers.

Old Dune Prairies are located inland of present beaches and associated dunelands. Examination of oceanside grasslands offers insight into relationships between area covered, community age, disturbance regimes, productivity and diversity. Old dune prairies predate jetties and accretion, and may be thousands of years old, representing plant communities that slowly migrated west in geologic time as sand spits built along the Pacific Ocean. They are highly diverse communities with more than 60 species, none of which are overwhelmingly dominant. Dune prairies are fire and drought tolerant. Accretion, urbanization, and fire suppression led to the isolation and loss of thousands of acres of habitat in the past century, of which less than two hundred acres remain in good condition. Losses continue today. Typical species include coast goldenrod, red fescue, California oatgrass, seashore lupine, coast piperia, twisted lady's-tresses, footsteps-of-spring, early blue violet, paintbrush, seaside tansy, fritillary, two brodiaes, short-stemmed sedge and two bluegrasses.

Young dune prairies grow on recently accreted dunes, made of sand with virtually no soil, and are less than 100 years old. They are dominated by non-native grasses, Ammophila arenaria and A. breviligulata, which constitute over 95% of the biomass in these plant communities. Several species within this dune community are not as fire tolerant as those on old dune prairies. While a few native species can be found in these areas, biologically these grasslands are much less diverse than the older dune prairies that predate the twentieth century. Scots broom and gorse rapidly colonize young dune grasslands, and can dramatically change their appearance and diversity in a few years. These grasslands are a short-lived transition between open sand and coastal shore pine forest, and on a particular site may last less than fifty years.

Sea cliff meadows have thin soils over rock, usually Miocene or Eocene basalt. They are located in salt spray zones, and are subject to high winds and year-round salt spray. These meadows are adjacent to coastal spruce forests, often found on the south and southwest-facing slopes of headlands while trees occupy other faces. Typical species include red fescue, sea-watch, paint brush, field chickweed, blue-eyed grass, Oregon iris. Nootka reed-grass and Sitka spruce are also typical of exposed headlands above tidal reaches; the trees are often severely sculpted by wind.

Balds have thin soil and little bare ground. They are found from near sealevel, though well above salt spray, to mountain tops. Common species include Oregon iris, blue-eyed grass, Alaska rein-orchid, red columbine, Columbia lily, chocolate lily, Cardwell's penstemon, Martindale's spring beauty, copperbush, bistort, clarkia and fawn lily.

Dry Cliffs & Rocky Slopes are bare, dry rock faces. Tough growing conditions produce the appearance of alpine habitats despite lower elevations and the lack of prolonged winter snow cover. Species include Columbia lewisia, spotted saxifrage tufted saxifrage, spreading phlox, and smooth douglasia.