My big RHS book says there are 2,T.distichum and says that T.ascendens is a synonym of distichum var.imbricarium. It doesn't mention what the second species is(1 species and 1 variety of that species) Looking on the Wiki it lists ascendens as a distinct species and also lists mucronatum as the 3rd(second?) species. It also says that this one is the world's stoutest tree at 11.4 m girth! So are there 3 or 2 species,and why doesn't my book list mucronatum at all,given its a big book with over 15,000 plants listed!