Good luck getting it. Check out Haiti from Google Earth, and you can see it is a barren rock. The eastern 2/3 of Hispaniola is the Dominican Republic, and it still has many of its forests. There may be refugia in Haiti, but I suspect these may not be well enough guarded.
I doubt if it is a tree, as such, probably a large weedy species. I have read from Alziar's list that it is a perennial with white flowers. A picture on the NYBG herbarium site, also mentioning that the flowers are white, indicates a very congested inflorescence, with many small flowers. Would love to see it, nevertheless, but Haiti is not a destination on my priority list!
I now have three plants of it, and hope it proves to be a reliable summer bloomer. We need good bee forage here in the southeastern USA. After the copious production of nectar from tulip poplars, summers offer scant nectar, and stressed hives undergo colony collapse.
It is supposed to have small blue flowers.
I'd also like to try out S. flocculosa from Ecuador. I saw this in the hills above Watsonville in 2008, and the plants were a mass of small deep blue flowers and reached 12 to 15 feet tall.