Get a box that is tall, Take out the top and bottom, and try and make the sides more round, cardboard will soon take on a rounded cylindar look. NEXT get brown paper bags, and lots of white glue or I used hot glue, but the sample I saw they used white glue. Take the brown bags and move them around to make the fibers soft,,, not sure that I"m explaining that right, but ask your art teacher... like in girl scouts when making a treasure map... then glue the brown paper bags to the cardboard box, creating the bark of the tree.
You can also take brown construction paper, like the large rolled kind at school and twist it into branches and vines. THIS makes great roots for the tree too!
Hope this helps.
p.s. they sell blow up palm trees (HA!)
Carpet roll tubes make excellent tree trunks, also coffee can, weighted with rice or sand, and then duct-taped together work really well too.
An area store carries jumbo mylar balloons and we had a monkey, a bunch of bananas, and the blazing sun. Also used dark green table covers feom the local dollar store. Mini-binoculars would be a cool door prize.
We used a Luau theme for two years. Our Carnival was held in our Gym and our building is set up where you come in the lobby and down a halway to get to the gym. We made these great palm trees out of brown butcher paper for the trunks. The trees were ceiling to floor in the hallway. We took an 12' section of brown paper and twisted it but not too tight. Then we took 2 more and made a tree trunk. Next we took dark green butcher paper in 4' lengths and used the scrunching technique to make leaves. Lastly we took light brown paper and made coconuts. We had approximately 10 trees throughout the hallway and it was a really cool effect.
Additionally we took some string, 2" dowel and stuffed animal monkeys (borrowed from PTO members)and hung them near the trees from the ceiling of the hallway.
If I'm not being descriptive enough let me know and I can email with more details.
Last year we had a safari theme for our carnival and found animal decorations at Oriental Trading. We also had some creative Mom's get some animal print fabric from a fabric store and used them for table runners on top of black tablecloths on our cafeteria tables, as well as draping them down the main hallway ceiling and on gym and cafeteria doors. They also used twigs and rugged sticks and put displays in corners and covered soup cans in animal print paper and used as vases on tables. It actually looked really good. Good luck with your carnival - hope this helps