The common black Mulberry (_Morus nigra_) has the general features of the order. The male flowers grow together in a dense spike, as shown in _fig._ 76 at _a_, and each flower consists of a calyx of four sepals, and four stamens, which spring back and remain extended after they have discharged their pollen (_b_). The female flowers also grow closely together, in dense spikes, round a slender receptacle; each having two elongated fringed stigmas (_c_), and a calyx of four sepals, and being inclosed in an involucre, as shown at _d_. As the seeds ripen, each female flower becomes a drupe, consisting of a fleshy and juicy pericardium formed from the calyx, and the nut; and these drupes being pressed closely together by the position of the female flowers, the whole adhere together and form the fruit we call the mulberry. The involucre withers when the calyx becomes juicy; but the remains of it and of the style are often seen on the ripe fruit, as shown at _e_. The receptacle also remains as a sort of core, which is thrown away when the fruit is eaten, though it does not part from it so freely as in the raspberry; and the little nuts, or seeds as they are called, are found in the centre of each juicy globule. The leaves are simple, entire, and rough on the surface. The white Mulberry (_Morus alba_) differs from the common kind in the fruit not being eatable; as the calyxes of the female flowers never become juicy. The leaves are, however, much smoother and of finer texture than those of the black mulberry, and they are principally used for feeding silkworms, for which those of the black mulberry are not so good. The red Mulberry (_M. rubra_) is an American species, with leaves too rough to be good for silkworms, and very indifferent fruit. The Constantinople and Tartarian Mulberries are supposed to be only varieties of _M. alba_, though their fruit is good to eat, and the latter has lobed leaves. The Paper Mulberry (_Broussonetia papyrifera_) has the male and female flowers on different plants. The male flowers are produced in pendulous catkins, and the calyx has a short tube before it divides into four segments; each flower is also furnished with a bract, but in other respects their construction is the same as that of the other flowers of the order. The female flowers have also a tubular calyx, and they are disposed in globular heads on rather long peduncles; but they differ from those of the other genera in having only a single stigma, and in the ovary being inclosed in an integument within the calyx, which becomes juicy as the seeds ripen, and not the calyx itself. The leaves are very irregularly lobed, and hairy; and the liber or inner bark is used for making what is called Indian paper.