“生态浮床”中的植物，能吸收水体中含氮、磷元素的无机盐，可防治水体富营养化污染，这些植物吸收无机盐的主要器官是____．

阅读下面这首古诗，回答两题。
                                                                                                           宿山寺
                                                                                             众岫耸寒色，精庐向此分。
                                                                                             流星透疏水，走月逆行云。
                                                                                             绝顶人来少，高松鹤不群。
                                                                                             一僧年八十，世事未曾闻。