Pale jewelweed (Impatiens pallida) and spotted jewelweed (I. capensis) are probably the most common native wildflowers along the Passage. Both are in bloom along the Great Allegheny Passage.
They prefer alkaline soil and the ballast from the former RR as well as the present trail surface material keeps the soil along the edges of the Passage neutral to alkaline. The best locations to see this common wildflower are the sunny openings where the forest canopy is broken. The Maryland sections, from Deal to Meyersdale, and much of the Passage from Connellsville to Boston are perfect habitat.
The accompanying photograph of pale jewelweed was taken on the section of trail between the Salisbury Viaduct and Garrett.
Both jewelweeds, or touch-me-nots, have a fruit that is a plump pod. The outer layer of the pod builds up unequal pressures between the surface and inner layers as the seeds within ripen. The tension builds and when you touch a fully ripe fruit it "explodes".
Well, not actually an explosion, but segments of the pod peal back rapidly. This launches the seeds into the air where they land well away from the parent plant. it's a way of getting the seeds into a new location, distributing the plant.
Aside from seeing mechanical seed dispersion in action, it's a lot of fun just to find ripe jewelweed fruits and watch them "explode".