Utricularia section Nigrescentes
Species	Range	Habit1
U. bracteata	Africa	T
U. caerulea	Australia-Asia	T
U. warburgii	China	T
1T=terrestrial.

Q: About Utricularia subgenus Bivalvaria section Nigrescentes

A: This section is characterised by the nature of its seeds and its traps. Indeed, the traps really are bizarre under a microscope---the front of the bladder has a huge appendage that, to me, evokes the big arching mouth of a humpback whale. Very cool.

Interestingly, the section name comes from the observed tendency for the plants to rapidly blacken as they are dried for herbarium specimens. Taylor, however, noted that this did not result if plants are dried rapidly and correctly. I will have to dry some sacrificial plants to see if they assume strange colors.


U. warburgii Utricularia caerulea
I have grown this plant a few times, and although it grew vigorously to flower and set seed, and then continued to grow as a perennial, it seemed somewhat fragile. Both times I grew it, the plants died due to minor irregularities in cultivation that would not have killed most terrestrials. I have grown both normally pigmented, blue/purple plants and a white-flowered form.

Utricularia warburgii
This plant is extremely pretty in flower. My clone, unfortunately, has not flowered for me in a terrarium. I am now growing this in a greenhouse and am hoping that seasonal cues will induce it to flower. The specimen given to me by Bob Ziemer was in fabulous flower upon its arrival. Bob grows his plants in a greenhouse, and his plants receive seasonal variations that mine do not.

Page citations: Rice, B.A. 2006a; Taylor, P. 1989; personal observations.