Fruit drupe attached to the receptacle. In some bramble fruits (such as blackberry) the receptacle is elongated and part of the ripe fruit, making the blackberry an "aggregate-accessory" fruit. The strawberry is also an aggregate-accessory fruit, only one in which the seeds are contained in achenes. In all these examples, the fruit develops from a single flower with numerous pistils. A multiple fruit is one formed from a cluster of flowers (called an "inflorescence"). Each flower produces a fruit, but these mature into a single mass. Examples are the pineapple, fig, mulberry, osage-orange, and breadfruit. In the photograph on the right,
Morphism of algebraic varieties "x" if there is a neighbourhood "U" of "x" and a neighbourhood "V" of ƒ("x") such that ƒ("U") ⊂ "V" and the restricted function ƒ:"U"→"V" is regular as a function on some affine charts of "U" and "V". Then ƒ is called regular, if it is regular at all points of "X". The composition of regular maps is again regular; thus, algebraic varieties form the category of algebraic varieties where the morphisms are the regular maps. Regular maps between affine varieties correspond contravariantly in one-to-one to algebra homomorphisms between the coordinate rings: if ƒ:"X"→"Y" is a morphism of affine varieties,