No, really. "Cow slobber" is one of the old-timey names for this lovely perennial, properly called Tradescantia. It's Latin name comes from John Tradescant, an illustrious plantsman of 17-century England. But the common name for this flower is spiderwort. Apparently it acquired the unattractive cow-related moniker because when the lax stems are severed, an oozing, stringy sap issues forth, resembling....you guessed it, cow slobber!
This charming plant is in bloom now, but just in the morning; its blossoms close by the heat of the afternoon. However, each stem bears many buds, so it's in bloom for a couple of weeks. And then, if the entire plant is cut back, it will rise and bloom again later in the summer.
Spiderwort appreciates a spot in moist, shady soil, where it brightens things up between the hosta and the astilbe. Easy to grow, easy to maintain, the only problem I've ever had with it is the year the voles wreaked destruction on the shady slope under a huge sugar maple. They took out much of the carex and major clumps of astilbe, too.
Most spiderworts seen in the nurseries are blue, but look for 'Sweet Kate', which has chartreuse foliage and pink flowers.
Another pretty plant with an interesting backstory.