You need to read page 3 of chapter 4 of the wood handbook. "Tensile strength parallel to grain. Maximum tensile stress sustained in direction parallel to grain. Relatively few data are available on the tensile strength of various species of clear wood parallel to grain. Table 4–7 lists...
Not sure what tropical species you are looking for, but a good resources can be found at the Forest Products Laboratory's website. The Wood Handbook Chapter 4 I believe would be helpful. You may download the chapter free in *.pdf format.
http://www.fpl.fs.fed.us/pubs.htm
