Hi guys
I'm currently still growing both species. Neither are too difficult to grow and I just use a standard mix of 3:1 peat/sand and have the pots sitting in water.
To get them to flower on the other hand is a little more difficult. Perhaps they need to be submerged first, then slowly let the water level recede may trigger the flowering, but I've never really experimented with it.
Both species have small leaves and can easily be overgrown by the noxious species like U. subulata and U. bisquamata. U. bisquamata's leaves look very similar to U. simplex, and are only a little narrower, so care must be taken to not get them infested as last year I almost lost both of these.
Of the 2 U. paulineae is a much nicer species when in flower and is a little bit like U. uniflora while U. simplex looks just like a variant of U. laterflora, the flowers are only a couple of mm wider and not very big, at around 5mm. Personally I wouldn't go to to much trouble to chase it down.
Cheers
Steve
U. paulineae
U. simplex
U. lateriflora