nunculus bulbosus, or Buttercup, in
section.]

256. =Flowers modified by Union of Parts=, so that these parts more or
less lose the appearance of separate leaves or other organs growing out
of the end of the stem or receptacle, are extremely common. There are
two kinds of such union, namely:--

_Coalescence_ of parts of the same circle by their contiguous margins;
and

_Adnation_, or the union of adjacent circles or unlike parts.

257. =Coalescence= is not rare in leaves, as in the upper pairs of
Honeysuckles, Fig. 163. It may all the more be expected in the crowded
circles or whorls of flower-leaves. Datura or Stramonium (Fig. 246)
shows this coalescence both in calyx and corolla, the five sepals and
the five petals being thus united to near their tips, each into a tube
or long and narrow cup. These unions make needful the following terms:--

_Gamopetalous_, said of a corolla the petals of which are thus
coalescent into one body, whether only at base or higher. The union may
extend to the very summit, as in Morning Glory and the like (Fig. 247),
so that the number of petals in it may not be apparent. The old name for
this was _Monopetalous_, but that means "one-petalled;" while
gamopetalous means "petals united," and therefore is the proper term.

[Illustration: Fig. 246. Flower of Datura Stramonium; gamosepalous and
gamopetalous.]

[Illustration: Fig. 247. Funnelform corolla of a common Morning Glory,
detached from its polysepalous calyx.]

_Polypetalous_ is the counterpart term, to denote a corolla of
_distinct_, that is, separate petals. As it means "many petalled," it is
not the best possible name, but it is the old one and in almost
universal use.

_Gamosepalous_ applies to the calyx when the sepals are in this way
united.

_Polysepalous_, to the calyx when of separate sepals or calyx-leaves.

258. Degree of union or of separation in descriptive botany is expressed
in the same way as is the lobing of leaves (139). See Fig. 249-253, and
the explanations.

259. A corolla when gamopetalous commonly shows a distinction (well
marked in Fig. 249-251) between a contracted tubular portion below, the
TUBE, and the spreading part above, the BORDER or LIMB. The junction
between tube and limb, or a more or less enlarged upper portion of the
tube between the two, is the THROAT. The same is true of the calyx.

260. Some names are given to particular forms of the gamopetalous
corolla, applicable also to a gamose