The only known wild grove of a tree species dating back 200 million years has been endangered by a disease that may have been introduced by a hiker who found its secret location. Fewer than 100 Wollemi pine trees grow in Wollemi National Park, near Sydney. But two have been infected by the fungus-like Phytophthora cinnamomi, probably brought in by an unauthorised visitor, according to the New South Wales Environment and Conservation Department. (AP)