Justicia americana; Acanthaceae (acanthus family)

On a mid-June weekend Steve and I walked along the C&O Canal towpath from Pennyfield Lock to Violette’s Lock.  The wildflower scene was lean.  I have a rule that’s a cynical twist on Murphy’s Law: if it’s found growing along the canal, it’s probably an alien. Sadly on that day the rule mostly held.  But then I saw this:

Tricky to photograph, as the plants were growing right in the water.  I couldn’t get any closer without sliding down the embankment into the water myself.  I figured these for aliens, too, but took some pictures, went home, and cracked open Newcomb’s.  And guess what?  They’re natives!

There’s another native with the common name water willow, Decodon verticillatus, aka swamp loosestrife.  They aren’t even closely related. Common names are an annoyance.

Water willow grows in colonies in wet soils or shallow water, from Texas east and north through Quebec.  It stands about three feet tall with narrow leaves; the purple and white flowers are borne on long stems arising from the middle and upper leaf axils.