The narrow fringe of ocean shore, the humid western slopes between the Cascades and the coast, the towering mountain ranges, the Columbia Basin with its extremes of summer and winter temperatures, and the intermontane plateaus -- each region has its distinctive flora. And in each, climatic and topographic factors have influenced the number of species and the abundance or rarity of flowers of the various species. More than 3,000 species are found. Among the native plants are some of the rarest specimens: Flett's violet and the exquisite Piper bluebell of the mountain tops, the phantom orchid of the deep Woods, the delicate rock pink of the Columbia Basin, and the sea rose of the coastal waters.
Conspicuous among marine plants are numerous algae, varying from blue-green to brown and red. Of this group the most common is the floating kelp with its brown-bulbed whip. The sea rose, rarest and most complex of the red algae, is found in its branched form, native only to the western coast of North America and the northeastern coast of Asia. Two species of eelgrass also grow here; one in exposed tidal waters, the other in protected marshes. Marine lichens and fungi of various kinds abound along the coast.
In season, even the sand dunes are abloom with sturdy plants. To windswept wastes cling the delicately fragrant yellow and pink abroma or sand verbena and the saltbush with pale, scurvied leaves; sand strawberries, beach pea, and blue, yellow, and purple lupine advance upon the rippling dunes, wherever some slight protection is afforded by driftwood or rock or hummock of solid earth. Fennel, spurrey, ruppia, willow, and the yellow-blossomed sneezeweed grow in rank profusion about the salt marshes.
Above the dunes and beaches along the littoral runs a narrow band of Sitka spruce, also called tideland spruce, a tree of great commercial importance. Douglas fir, a species forming the greater part of the stand in the rain belt between salt-water shores and the Cascade Mountains, is tall and stately, of great strength, comparative lightness, and straight grain. First reported by Archibald Menzies at Nootka Sound in 1792, it was known as Oregon pine until named in honor of David Douglas, who introduced it into Europe in 1827. Other conifers are the western hemlock, known for its size, drooping branches, and gracefully tapering trunk; western red, Port Orford, and Alaska cedars; and, in the mountains, the six-leaved pine and the silver, white, and noble firs. Winter and summer, these forests keep their green ranks closed against the winds, their moss-hung boughs blotting out the sun. Today, wilderness roads wind between the green walls made by these ancient forest giants, whose branches, interlacing overhead, sough and murmur in vagrant winds. Seen from an elevated vantage point, seemingly miles of dark-green brushy tips cover the valley floors and sweep up the mountain slopes, staggering as they near the rocky summits. Scattered through the coniferous forests at the lower levels is the madrona, with its red-skinned trunk, classed as an evergreen because its new leaves have formed by midsummer, when the old ones fall.
In most of the forested areas of lower altitudes are several deciduous species. Common among these is the big-leaf maple, usually found as an incidental tree growing in clumps or singly among the conifers. In bright contrast to the evergreens is the vine maple, so called because of the sprawling appearance of its weak and crooked stems. In the spring, its leaves are a gorgeous rose red; in the fall, reddish yellow or bright scarlet. Other hardwoods are the red alder, one of the first species to take possession of burned or cut-over land; the black cottonwood, found only at lower elevations in coastal regions; the Oregon white, or Garry, oak; the western yew, the California myrtle, and the Oregon ash. Most spectacular is the western dogwood, easily recognized in spring by the button-like clusters of small, greenish-yellow flowers, surrounded by four to six snowy white, or slightly pink, saucer-like scales, popularly presumed to be petals of the real flower. Late in summer the foliage turns a brilliant scarlet and orange, and the small seed-like fruit becomes bright red; autumnal flowers are not uncommon. Abundant also are shrub-like hazel trees and Cascara-buckthorn trees, whose bark is used in making cascara sagrada.