This species was very recently described by Patrick Alexander -- 2008! Molecular data suggest that this species does not have any especially close relatives (it is on a "long branch"), but otherwise it has been difficult to place. Certainly in morphology it is similar to the H. hallii-H. bracteata group and may tentatively be placed there.
This species is apetalous -- a condition that otherwise obtains only in H. chlorantha, H. cylindrica, and H. eastwoodiae. Actually, petals are best described as "very rare." The petals are unusual in being densely glandular.
The habit pictures come from the type locality, which P. Alexander graciously assisted me in locating. The floral close-ups are cultivated plants from the same locality. Two petals may be clearly seen in the second photo.
Flowers:
Habit: