Crab apples are a pie favorite. They are tiny yellow apples with a red to maroon blush. They have a tart flavor. Three varieties are available October through January from California, New York and British Columbia. Hyslop is three-quarters the size of a golf ball. It is yellow with a red/blue blush. Red Siberian is the size of a large marble and is dark purple-red. Crimson Gold is golf-ball sized, yellow with a red blush and a sweet and tangy taste.