That was my initial reaction at first as well. However as far as I can tell, natural products are not patentable, unless the product in question has been modified, manipulated etc, to produce something that is deemed to have been significantly changed.
So, in the US, for example, the Supreme Court ruled that human DNA, being a naturally occurring product, cannot be patented. However, it also ruled that complementary DNA, essentially DNA that has been extracted and then modified in a lab, can be patented.