Mexican Hymenocallis ID

[cshunter]

Hi: Trying to get an ID on what I believe is a Mexican (rather than USA) species of Hymenocallis that I acquired as Hymenocallis lehmillerii, but other Mexican Hymenocallis I got at the same time were misidentified, so I want to confirm the ID on this one. It surprised me by blooming out in the garden earlier this month with three blooms on consecutive days (9-9. 9-10 and 9-11). Each bloom faded pretty quickly after its first day, as you can see in the attached pictures.  

I am pretty sure it is a Mexican one, as I either grow or have seen blooming most all of the American ones, and this one is different. Also, flowers have greenish filaments, which is consistent with lehmillerii but I think also with some other Mexican ones, and you can see an unopened flower in at least one picture with green in the flower tube. Leaves are a bit darker green than some, glossy, and are 1 inch wide at widest point in the center, NOT petiolate.  The flower stem (now with seed pods at the tip) is the tallest part of the plant at 20 inches above the ground. I have harvested a few seeds already, which are quite small. 

As you can see by the photo with the tape measure, the staminal cups are small on this one and flower is about 4 inches from tepal tip to tepal tip. The first picture that shows a flower without a clearly discernable cup was taken the morning after a very heavy rain, which I am sure damaged the cup- other 2 blooms have cups. 

This Hymenocallis is planted in my zone 7b garden (north suburban Atlanta) year-round and is in some part shade, making me think it might be a woodland plant in its native habitat, as I know some Mexican species are. Not sure a sun-loving one would have bloomed and made seeds where it is. 

I know there are at least a few folks in PBS that know Hymenocallis from south of the border, so hoping you can help me ID this plant. There is not a good reference publication or key that I am aware of for the Mexican ones. Late bloom time should narrow it down a bit I would think. Thanks.

Charles in Smyrna, Georgia