Charles Day is Wave Hill’s Ruth Rea Howell Horticultural Interpreter.
This Korean species of hosta is very strange. The flowers resolutely refuse to open—explaining the clausa (closed) part of the botanical name.
It is an odd mutation because insects and other pollinators cannot get inside to transfer pollen and, unsurprisingly, the plant produces no seed. In the wild, it is only found in localized patches, for the simple reason that without the ability to distribute itself by seed, it can only spread by vegetative means; that is, by producing new plants on creeping underground stems (stolons).
This spreading habit can be useful in helping to prevent soil erosion on steep slopes—hence these plantings on the banks just to the north of the Aquatic Garden.
Hosta clausa does best in partial shade and has been planted in the less sunny sections. Another stoloniferous hosta, but one with more conventional open flowers, is the variegated hybrid Hosta ‘Queen Josephine.’ It is more tolerant of sunlight and can be seen growing in the midsection of the long bank.