What is a scientist who studies plants called?

What is a plane figure with seven sides and seven angles called? A planetarium in which state capital bears the name of Christa McAuliffe, who died in the 1986 Challenger explosion? Which 1919 W. Somerset Maugham novel, inspired by Gauguin, has a title pairing a planetary satellite and half a shillin… Which plant of the parsley family is known as Apium graveolens? A plaque in Yankee Stadium's Monument Park honors which former cardinal for a 1979 event held at the stadium? A plaque in the Louisiana State Capitol marks the site of which violent event of September 8, 1935? A plaque left on the Moon in July 1969 has the signatures of Neil Armstrong, Buzz Aldrin and which two other men? What is a plaster cast made of a living person's face called?