So here are some more details about the N. acuminata that I am growing.
This is a picture of my shade tent that I built to go over the N. acuminata plants. Unfortunately I've discovered the sun is still often low in the sky and shines from the direction that shot is taken so I am not sure how effective my tents will be (but the one I put of that N. alata seems to have dramatically cut down on daytime wilting).
I tried to get a good shot of a single plant but it wasn't easy. It's sort of a roseate of petiolate leaves at the base and then the stem rapidly elongates to produce the flowers, which are not closely spaced (as you can sort of make out by the placement of the capsules). The leaves are basically lanceolate (you could also call them ovate) with acuminate tips (where I think the name comes from).
The flowers are about 3" long and pure white with a green hue on the outside of the corolla tube. The limb is quite large with 5 distinct lobes. Unlike regular tobacco, there is no throat enlargement so the opening is quite small; probably evolved for moth pollination.
Another unique characteristic I have noticed is that it has very long sepals that are cut down very far into the whirl, like long little fingers.
The capsule is roughly shaped like that of regular tobacco (ovoid), but smaller. When ripening the capsule will crack open along the seem, but not fold back to make the goblet as other species do. The seeds are roughly the size of those of N. rustica and maybe 300-400 per capsule. The seeds in the photo below are a little damp so they appear darker, when the true color is no different than rustica seed (which I feel is about a shade darker than regular tobacco seed).