Read it through once

Among plants we find all sorts of transitions and degrees of cannibalism. There are plants which sometimes, and, as it were, accidentally, attack others. But there are also real cannibal plants which live entirely on the life-juices and sap of other plants, and cannot exist by their own labours at all. Moreover, we can find almost every conceivable state of transition. These can be clearly and definitely traced from those plants which depend on the labour of their own roots and leaves to others which have no leaves, and which consist merely of one large flower and a large adhesive sucker fixed on some one else's root.