Here's a sampling of the wildflowers I've seen along the Chilnualna Falls trail at one time or another. Which ones you see will depend primarily on what time of year you're there, and because of the vast elevation change on this hike, you'll probably see different flowers at the bottom of the trail than you do at the top.
Snow Plant will typically be the first to appear, in shady places right after the snow melts. Flowers like Harlequin Lupine and Hartweg's Iris will show up early in the season along the lower parts of the trail, while you'll probably have to hike to the base of the upper cascade later in the summer to see Western Azalea in bloom. Bear Clover, whether in bloom or not, carpets most of the clearings in the middle parts of the hike. Congressmen will take vows of poverty and Charlie Brown will kick the football before you hike the Chilnualna Falls trail without passing Bear Clover.