
Purple Dead-Nettle (Lamium purpureum) growing from the stone wall under a railroad overpass at the back of the South Side Flats. In this sheltered position, it was already blooming in early March.

Urban weeds are different from suburban or rural ones. Petunias often escape and pop up in cracks of sidewalks. Usually these volunteer seedlings have smaller flowers than their hybrid ancestors, and often in more washed-out colors. This flower was blooming from a concrete stairway on the South Side Slopes.
Butter-and-Eggs or Toadflax (Linaria vulgaris) is a kind of wild snapdragon that came from Europe as an ornamental and made itself weedily at home. These plants were growing out of sidewalk cracks on the South Side Slopes. Note the two different color phases: one with bright orange centers, the other a more uniform primrose yellow.
This American native is one of our most beloved garden flowers. It blooms most of the summer, and it tolerates a wide variety of conditions. Butterflies love it, too. You can often find it growing wild around Pittsburgh, but it is currently one of the most fashionable garden flowers. This is a semi-wild specimen: it was a volunteer seedling whose parents were deliberately planted nearby.
In honor (apparently) of its Japanese theme, the 2015 Fall Flower Show has visitors keeping to the left instead of to the right all the way around the conservatory (except in the Fern, Orchid, and Stove Rooms, because a foolish consistency is the hobgoblin of little conservatories). It makes old Pa Pitt wax nostalgic, because Phipps was a keep-to-the-left place for the first century or so of its existence, before finally converting to keep-to-the-right circulation at some time in the late twentieth century.