Biological diversity is a hallmark of the Columbia River Gorge, which encompasses two natural transitions in its 80-mile length

The first of these is the east to west transition which begins with near-rain-forest conditions in the western Gorge and changes dramatically within a relatively short distance to arid, near-desert conditions in the eastern Gorge.  This transition is driven by the "rain shadow" effect of the Cascades.  As rain-laden storms from the Pacific Ocean reach the mountains, the air masses gain elevation and become cooler, less able to hold moisture.  In short, it rains a lot in the western Gorge.  As the storms pass the crest of the Cascades, they lose altitude and become warmer; warm air holds more moisture, and less of it falls as rain.  The eastern slopes of the Cascades are much drier as a result.

The second transition is in altitude.  The tallest ridgelines of the central Columbia Gorge exceed 4,000 feet above sea level. Just as spring comes later in the season as we approach the poles, it also comes later as we gain elevation (if you miss the annual bloom of a given wildflower at lower elevations, oftentimes you can climb higher to find it still blooming).  All these natural variables - rainfall, temperature, sunlight and shade - create a multitude of what ecologists refer to as "microclimates," relatively small regions of unique conditions that encourage the growth of unique species.  In the Columbia Gorge, that's particularly true of wildflowers; there are hundreds of species here, many distributed throughout the Gorge but some isolated to limited regions.

There are over 800 species of flowers in the Gorge; fifteen of these are endemic and are not found anywhere else in the world. You can learn a little about each of these "endemics" below...
Barrett's Penstemon  (Penstemon barrettiae)
A tall pink penstemon blooming in rocky areas early to mid-May in the eastern Columbia Gorge.  Can be found along the cliffs of the old Historic Columbia River Highway.
Columbia Desert Parsley  (Lomatium columbianum)
With bright pink flowers blooming March to May in the eastern Columbia Gorge.
Columbia Gorge Broad-Leaf Lupine  (Lupinus latifolius)
A lavendar lupine blooming April to May at Rowland Lake, near The Dalles Bridge, and Dalles Mt. Road.
Columbia Gorge Daisy  (Erigeron oreganus)
Blooms mid-June around Oneonta Gorge, Latourell Falls and McCord Creek.
Columbia Kittentail  (Synthyris stellata)
Blooms on shaded banks late March to early April, Wahkeena and Horsetail falls.
Hood River Milk-Vetch  (Astragalus hoodianus)
With cream-colored flowers blooming late April to early May at Mayer State Park, near the intersection of Washington Highway 14 and 197, White Salmon River, Horsethief Butte, and Hood River Mountain Meadow.
Howell's Daisy  (Erigeron howellii)
Blooms on rocky slopes late May around Multnomah Falls and early July atop Larch Mountain.
Long-Beard Hawkweed  (Hieracium longiberbe)
Tightly packed pale yellow flower heads, at the top of wand-like stems.  Blooms July through August and can be found at Angel's Rest and McCord Creek Trail.
Northern Wormwood  (Artemisia campestris)
Low-growing (to 30 cm) with leaves and stems covered with fine, silky hairs.  Blooms mid-April to mid-June.  Most of the suitable habitat was submerged behind Bonneville and The Dalles Dams but the historic range extended along the Columbia River from the mouth of the John Day River to Bingen, Washington
Oregon Sullivantia  (Sullivantia oregana)

Delicate, yellowish-green perennial spreading by long slender stolons, with hairs that are mostly purplish-tipped.  Blooms May through August and is found on moist cliffs in the western section of the Columbia River Gorge, especially near waterfalls
Poet's Shooting Star  (Dodecatheon poeticum)
Has pink and yellow blossoms blooming March to April at Tom McCall Nature Preserve and east of Lyle.
Smooth Desert Parsley  (Lomatium laevigatum)
Yellow but not as tall as Suksdorf's Desert Parsley.  Blooms early to late March and found near Columbia Dam, Wishram Cliffs, North end of US-97 Bridge.
Smooth-Leaf Douglasia  (Douglasia laevigata)
Named for pioneer botanist David Douglas.  Blooms early April at Mitchell Point, McCord Creek Falls.
Suksdorf's Desert Parsley  (Lomatium suksdorfii)
Named for Wilhelm Suksdorf, early botanist whose family helped establish the City of Bingen, a yellow, 2-6 foot lomatium blooms late April to early June, and can be found near Chenoweth Road and Nestor Peak.
The Dalles Mountain Buttercup  (Ranunculus reconditus)
A yellow buttercup blooming in open grasslands, early to mid-March along Dalles Mountain Road.
"You're free to look at them and take pictures - but please don't pick!"