If you don't get a definite answer here, you might ask in the Fruit & Orchards forum. Can you take a larger, clearer picture of the pit? They can also advise about pruning off the dead branches and evaluating what's left of the tree. http://forums2.gardenweb.com/forums/fruit/ Was the fruit soft when you tasted it? If not, it probably wasn't ripe yet. There are some plums which are green when ripe, but it's not a common color for ripe fruit.

It would be easier with the branch in my hands (as you have it), but even from the pictures, it took me about 15 minutes online to google the search terms you were *handed* about this plant, and narrow it down to a few possibles. It took another 10 to go through pictures for the possibles, and get it to one. (((Are weeping cherry or black tupelo (of all things...) used in South Asian cooking???))) Now, do your own homework!! Follow the trail of breadcrumbs you were given! Use your brain, and track it down. Then, if you need to be sure, use your nose. Crush a leaf and smell it. And talk to someone who cooks. Again..... Do your own homework!

They look like tall asters of some sort. They grow wild here and I have lots of them. They bloom in late summer and through early fall. They spread from roots and seeds that can blow in the breeze from other areas. They can be invasive in moist soil. Covered in beautiful little star-like flowers in either blues, pinks, whites or lilac colors. That is what I would say they are - Asters. However, there is another WEED that looks much like that. Has minimal flowers and isn't worth keeping. If they are those, PULL THEM OUT! Check out the link below. I have all of these asters growing on my property and in my garden. ~Annie Here is a link that might be useful: Take a look at these photos of wild asters

Could possibly be a Crinum species or hybrid. Where are you located?