how nmany times must you do this to solve the puzzle? I have done this many times,but still no puzzle solved? and also sorry so many questions on this puzzle,just wanted to be sure I was doing it right or not.

my villager didn't want to co-operate with me but it worked when i did this

Well, almost

I think you just were going too fast at one moment. If the butterflies followed your villager until this point, they'll follow him until the tree!!
Just try again, slowwwwwwwwly!!

does he have to be a master in something. I have tried just about everyone and they act very confused. Can't even get them to cut the vines. And where are the vines located at I have had the stream going for three days.

No, he doesn't have to be master, any adult villager is able to do it.

At the beginning, he'll go to take a cutting tool. Are you sure there are some cutting tools in the research lab?

The best manner to know if the plant is "ready" is that it's surrounded by the butterflies.

When you can see a kind of green "fog" around him, you may start to the tree.

You mention vines. Are you sure you aren't getting confused with another puzzle? This thread relates to the butterflies puzzle. The plants referred to here are a clump of reeds by the stream, near the blackberry bush. Drop a villager there and s/he'll go to fetch a cutting tool. See earlier in the thread for more help.

Vines appear in the solution for Puzzle #8.

Btw u do not need Lvl2 Dendrology. I did it with lvl 1