The Antonov An-2 is notable for being able to fly at a very low speed. However, what confuses me is that it has no stall speed:
The An-2 has no stall speed, a fact which is quoted in the operating handbook. A note from the pilot's handbook reads: "If the engine quits in instrument conditions or at night, the pilot should pull the control column full aft and keep the wings level. The leading-edge slats will snap out at about 64 km/h (40 mph) and when the airplane slows to a forward speed of about 40 km/h (25 mph), the airplane will sink at about a parachute descent rate until the aircraft hits the ground."
(From Wikipedia article on An-2)
How is this possible? What makes the airplane have no stall speed?