1197. The tubular calyx exhibits likewise three stages of development. At first it is scale-like, confluent with the ovary or epigynous--_ovarial corollæ_. It is next spathe-like, simply connected with the corolla or perigynous--_calycine corollæ_. Lastly, it resembles the reticular-veined leaf, being free from both the above organs, or hypogynous--_pedunculate corollæ_. c. _Corolla._ 1198. From the character of the corolla or crown as being a ramular leaf all its properties admit of being deduced. It is the upper leaf-bud, inasmuch as the ramular leaves stand above those of the stalk. It is, on this account too, the internal, inasmuch as the lower leaves admit within them the upper. 1199. The corolla is homologous with the whole mass of the petiolated or ramular leaves. Thus their arrangement, form, and number taken together are not worth more than the characters of the corolla, nor are they worth less, because they are relations of deeper organs. 1200. The corolla stands also in a whorl, because it is the totality of leaves. 1201. The laws of the leaf-formation are also the laws of the corolla-formation. The corolla will therefore represent at one time a greater, at another a less, ramified leaf-system. 1202. The corolla is the last verticil in the series of leaf-whorls; for it represents the last leaf-form, and must fade, because the tissues have completely separated from each other, namely, the tracheæ as stamina, from the cells that constitute corolla leaflets or petals. No part can carry on life by or for itself. 1203. The parts of the corolla range in an alternating manner with those of the calyx, because they are the next supra-consecutive bud. 1204. In accordance with the three stages of the leaf-formation the corolla is also resolvable into three forms. The scale-or root-leaf returns in the several squamiform micropetals of what have been called the Apetalous plants; it corresponds to the involucrum--squamoid corolla. The spathe-or stalk-leaf appears in the tubular-shaped or Monopetalous corolla. It is a leaf-bud, which has only ruptured at the apex, like most calyces, unto which it corresponds--spathoid corolla. Lastly, in the polypetalous corolla the reticular or petiolated leaf appears upon its highest stage--reticular or phylloid corolla. The rank of the leaves consequently determines also that of corollæ. 1205. Although we regard the corolla as a whorl of leaves, namely, as several leaf-buds approximated, a yet clearer insight into its numbers and positional relations is attained, by viewing it only as the lobes of a single leaf.