Botanist, who was allegedly brought to Area 51 to help with a sick, plant-like alien, who liked strawberry ice cream.

According to Bill Cooper at the 1989 MUFON Symposium:

In late 1951 EBE became ill. Medical personnel had been unable to determine the cause of EBE’s illness and had no background from which to draw. EBE’s system was chlorophyll based and he processed food into energy much the same as plants. Waste material was excreted the same as plants. It was decided that an expert in botany was called for. A botanist, Dr. Guillermo Mendoza, was brought in to try and help him recover. Dr. Mendoza worked to save EBE until mid 1952 when EBE died. Dr. Mendoza became the expert on alien biology.

He was also an informant of Jacques Vallee:

He nursed the one alien who died. He was a biologist, not an M.D. By the way, they did feed that alien ice cream, which he could eat in small quantities through a membrane in his mouth, and he did like strawberry. And he was partial to Tibetan music. That part of the Seligman Cover-Up documentary was true.”
– Revelations, 74, 81