The title doesn't refer to some obscure species or to one overlooked by neglectful botanists. This plant is not particularly rare, and I'm the only negligent party here. I discovered my negligence while looking through the album of photographs that I've posted here over the last few months. I realized that despite having made a couple of posts featuring my small collection of "specialty" Sansevieria plants, most notably this post, I have never shared a picture of one of my favorites: Sansevieria fischeri. This plant used to go by the name Sansevieria singularis; in fact, that was how it was labeled when I purchased it three years ago. (By the way, I'm using the term "specialty" to denote plants belonging to species other than the more commonly grown S. trifasciata varieties. In all other ways, every Sansevieria is special as far as I'm concerned.)
Like some other Sans, this species has both juvenile and adult forms. Juvenile plants have short, grooved leaves grouped in rosettes. The leaves in the adult form are taller, more cylindrical (not to be confused with S. cylindrica) and look like more like single leaves, rather than part of a rosette. In my pictures, the leaves on the left are still clearly in juvenile form, while the leaves on the right are starting to look more mature, though they aren't there yet.