The plants in this family have a _curved ovule_, and most frequently a _kidney-shaped seed_ (generally provided with fine, cuticular, projecting warts, Fig. 362 _B_), with a _curved, peripheral embryo enclosing the endosperm which is most frequently floury_ (Figs. 362 _C_, 365 _H_; for exceptions, see Fig. 366); the seeds in all cases are borne on a _centrally-placed_, and in most cases _free_, placenta (they are “basal” when there is only 1 ovule in the ovary, Fig. 364). The flower is regular, hypogynous or perigynous (Fig. 364) (only rarely epigynous) and usually 5-_merous_. The flower which is most complete has 5 whorls (S5, P5, A5+5, G2-3–5), as in some genera of the Caryophyllaceæ (Figs. 360, 361); but from this type it becomes reduced, the petals and stamens being suppressed, so that finally 5 perianth-leaves, 5 stamens (opposite the perianth-leaves), and 2 carpels (Fig. 361 _F_) only are present; for example, in certain genera of the _Caryophyllaceæ_, in the _Chenopodiaceæ_, _Amarantaceæ_, and others. When the number of stamens is increased to more than 5 in the whorl, it is always possible to show that some of the stamens have been divided. The number of the carpels and ovules also becomes reduced; in the highest there is a central placenta, not free in its early stages, with a large number of ovules; in those which are most reduced there is only a single ovule, which is placed centrally at the base of the ovary [Fig. 364]. Somewhat corresponding changes are found in the fruit, which is a many-seeded _capsule_ in those which have many ovules, but a one-seeded _nut_ where there is one ovule. In the most reduced forms the flowers are generally unisexual.--Similar features are also present in the vegetative parts. Almost all the species are herbaceous, the leaves are simple and most frequently without stipules. ~The structure of the stem, especially in Chenopodiaceæ, Amarantaceæ, Nyctaginiaceæ and others, often differs from that of the ordinary Dicotyledon. In the woody portion of the stem and root several rings are sometimes formed which resemble annual rings but which are formed by new cambium-rings arising outside the old ones which then cease to divide.~