This is a result of a "sea bean" that was found on Moloaa Beach on the north shore of Kauai in July of 2017. Unfortunately, I did not take a photo of the seed. The seed was about 3cm in diameter, about the size, shape, and texture of a chestnut. However, it was a pale grey color with a dark grey variegation. I put it in a bag with the rest of the "sea beans" I had collected, but then noticed a small budding growth about a week later, so into a pot of perlite it went. I kept it moist and in a south facing window and grew nicely. I have searched the internet on ID sites and images, but have not found a seed, nor an image that fits this plant. I do not know if this is a Hawaiian native or a "traveler of the seas", but am interested to see if anyone can ID this.
Welcome to the forums. I feel I need to start with a disclaimer, that my reply is not a particularly educated one. I just ran across a page on sea beans some years ago and wondered if it would be of any use. Your plant looks leek-like, so Amaryllidaceae family anyway. I'm not sure if there is anything else in the running. In case I have the right idea, here are some Amaryllidaceae in Hawaii: Amaryllidaceae - Plants of Hawaii - Starr Environmental I'd have questioned whether it was growing from the seed you collected and not already in the soil, but you're pretty clear about having seen the growth before planting it. I like this Drift Seeds and Drift Fruits page, which is not actually any help in this instance, but I'm including the link because it's a nifty page. It mentions Crinum asiaticum as a tropical drifter. There is a photo of some old seeds here: Hong Kong Herbarium-HK Plant Database-Crinum asiaticum L. var. sinicum (Herb.) Baker. I don't find the leaves all that convincing.
I am thinking I may have to wait and see how this plant matures, if it flowers, changes morphology,...whatever. The seed was of generous size,...that would mean a very large plant typically. Time will tell. I will see what it does this summer now that it is in a larger pot, perhaps posting some photos later on. In my experience, most things are pretty simple, and it is likely it is a common plant,...perhaps a juvenile Crinum asiaticum, as Wendy suggested.
