After all the parts of a flower have been removed there remains, as a rule, a small core or axis, which is the receptacle, and is really a very short piece of stem that bore the various floral leaves just described. It undergoes many modifications in different plants. In the Buttercup and Wallflower it remains small; in the Strawberry it becomes enlarged and pulpy (fig. 51); in the Raspberry and Bramble it becomes large, conical, and spongy; in the Apple it grows up around the carpels, completely enclosing them, and, though only a fleshy, cellular flower stalk, it forms the edible portion of the fruit. The receptacle of the Cherry or Peach forms a little cup round the base of the ovary, and carries the sepals, petals, and stamens on its edges. In the Rose or Brier it forms a hollow tube enclosing the carpels, and becomes the brightly coloured hip at maturity. The Fig is also a hollow receptacle, enclosing a whole inflorescence of numerous small flowers.

A Dioecious Plant.

Fig. 63. - A Dioecious Plant.

1, Twig of Crack Willow (Salix fragilis), with pistillate (female) catkins. 2, Twig of same with staminate (male) catkins (nat. size).

A flower is said to be hermaphrodite when it contains both stamens and pistil; male, when it contains stamens only; female, when only the pistil is present. A plant or tree is monoecious when male and female flowers occur on different parts of the same individual, as in Begonia, Cucumber, Marrow, Oak (fig. 52), and Melon; and dioecious when only male flowers occur on one individual, and only female on another, as in the Willow (fig. 53), Poplar, Aucuba, and Ash.