Thank you! There's definitely bamboo in Africa - Google turns up plenty of evidence. Thanks for the photos of palm trees... I think I should take them as 'permission' to get out my box of 'desert' scenery and use them!
And also, I need to remember that this game (Congo) is more far more game than it is history; it's much more 'pulp fiction' than it is cold, hard, fact. Therefore, if I fancy palm trees, I darned well ought to have palm trees!