One summer we had a visit from the owner of a well-known wholesale nursery, and as we came up the driveway past our patch of Hosta clausa, he asked what sort of Convolaria (Lily-of-the-valley) it was, and didn't believe us at first when we told him it was a hosta.
Everything about this species is different. Instead of tight clumps, it runs, forming a ground cover of nearly erect leaves. And then, in late summer, it gets even more unusual when it starts flowering.
Instead of the usual washed-out mauve blooms, it forms spikes of dark purple flower buds that shift to almost magenta at their bases. Even stranger, those buds never open, but stay as tight little balloons that keep on coming for weeks and weeks. Hands down the brightest, most wonderful flowering of any hosta, and sets everyone drooling the moment they see it, especially since it performs in late summer when the shade garden is apt to get a little dull.