Linnæus distinguishes seven parts of fructification, some of which are essential to the very nature of a flower or fruit, others not so indispensably necessary, and therefore not universal.
I. Calyx, the Calyx or Flower-cup, generally resembling the leaves in texture and colour, and forming the outermost part of a flower. This is not essential, and is often absent.
II. Corolla, the Corolla, or more delicate coloured internal leaf or leaves, properly petals, of a flower, likewise not essential.
III. Stamen, or Stamina, the Stamen or Stamens, commonly of a slender or threadlike form, bearing some kind of knob or cellular body, and ranged internally with respect to the Corolla. These are essential.
IV. Pistillum, or Pistilla, the Pistil, or Pistils, in the centre of the flower, consisting of the rudiments of the fruit, with one or
