Hello, 
I haven't messaged here in a while... I bought some worm castings from a local farmer to use in my houseplant mix this summer. Turns out it had lots of seeds in it. I got maybe 12 random seeds grow and a few of them veggie plants I put in the garden. The most interesting one is this one in the pictures. the leaves fold up downwards at night and come back out at sunrise. My first thought was Tamarind, but the seed casing was more long than round. I live in Nova Scotia Canada, and have the plant in my university dorm in an east facing window. I could put a grow light on it for the coming winter though. Any idea what it could be? The roots have started coming out of the tiny pot, should I put it in a bigger training pot? Maybe i should fertilize it? the latest leaf group has had 3 rows of leave where as the last two had 4 rows. 

If you want to narrow down possible species start with what trees can be found around you. The likeliness of a local farmer that produce worm casting in nova scotia ends up with tropical seeds in his product seems very low.

To add on to the likellyness discussion. It is highly unlikelly that any tree grown from a andom seed that came in a novia scotia produced worm casting can be grown in livingroom conditions. So without knowing species, the best bet would be to grow it outdoors.

on your question about fertilizer, now is not the time of the year to fertilize.

Thanks for the reply, 
I haven't found any plant here in NS that looks like it. I already asked on another plant forum and they said tamarind, but I too am doubtful. I'm not sure how it ended up in there. My best guess is someone was eating tamarinds and put the pits in the worm bin. it could be a Caesalpinia pulcherrima or something maybe, but again even more unlikely to end up in a NS worm bin. I just thought someone here might know the species. Since it's in my dorm I don't really have a great outdoor space, so I will just see how it goes inside. 

Thanks,
Si

Yes, it make sense that the tree could come from something eatable that is imported. But when I look at pictures of tamarind seeds they are huge. I would expect it to be sifted away during production. If not sifted away, still you would notice them right?
 

Here is the seed casing that fell off of the cotyledons. It's almost 2.5cm. I must have just scooped it up when I filled the pot. It looks too long and not round enough to be a tamarind, but still unsure. 

Here is a better picture with the leaves out