The _labiate_ corolla is characteristic of the mint family where the gamosepalous corolla is unequally divided, so that the two upper lobes are sharply separated from the three lower forming two “lips.” The labiate corolla of the toad-flax, or snapdragon is _personate_, or _masked_, because the lower lip arches upward like a palate and closes the entrance to the corolla tube; that of the dead nettle (_Lamium_) is _ringent_ or _gaping_, because the lips are spread wide apart. In some plants the labiate corolla is not very marked and differs but slightly from a regular form. The _ligulate_ or _strap-shaped_ corolla is characteristic of the flowers of the dandelion or chicory, or of the ray flowers of other composites (fig. 451). The lower part of the gamosepalous corolla is tubular, and the upper part is strap-shaped, as if that part of the tube were split on one side and spread out flat. These forms of the flower should be studied in appropriate examples. =813. Union of flower parts.=—In the buttercup flower all the parts of each series are separate from one another and from other series of parts. Each one is attached to the _receptacle_ of the flower, which is a very much shortened portion of the flower axis. The calyx being composed of separate and distinct parts is said to be _polysepalous_, and the corolla is likewise _polypetalous_. The stamens are _distinct_, and the pistils are _simple_. In many flowers, however, there is a greater or lesser _union_ of parts. =814. Union of parts of the same series or cycle.=—The parts _coalesce_, either slightly or to a great extent. Usually they are not so completely coalesced but what the number of parts of the series can be determined. Where the sepals are united the calyx is _gamosepalous_, when the petals are united the corolla is _gamopetalous_. Union of the sepals or of the corolla is quite common, but union of the stamens is rare except in a few families where it is quite characteristic. When the stamens are united by their anthers, they are _syngenœsious_. This is the case in most flowers of the composite family. When all the stamens are united into one group by their filaments, they are _monadelphous_ (one brotherhood), as in hollyhock, hibiscus, cotton, marsh-mallow, etc. When they are united by their filaments in two groups, they are _diadelphous_ (two brotherhoods), as in the pea and most members of the pea family. In most species of St. John’s wort (Hypericum), the stamens are united in threes (_triadelphous_).