unction. The occurrence of heteromorphic unions renders
it necessary to keep in mind that plants hermaphrodite as to structure
are by no means necessarily so as to function.

The simplest case of this alteration in the relative position of the
sexes is that which occurs in monoecious plants, where the male and
female flowers have a definite position, but which in exceptional
instances is altered.

=Change in the relative position of male and female flowers= may thus
occur in any monoecious plant. Cultivated maize, _Zea Mays_,
frequently exhibits alterations of this kind; under ordinary
circumstances, the male inflorescence is a compound spike, occupying the
extremity of the stem, while the female flowers are borne in simple
spikes at a lower level, but specimens may now and then be found where
the sexes are mixed in the same inflorescence; the upper branching
panicle usually containing male flowers only, under these circumstances,
bears female flowers also.[190] In like manner, but less frequently, the
female inflorescence occasionally produces male flowers as well.

Among the species of _Carex_ it is a common thing for the terminal spike
to consist of male flowers at the top, and female flowers at the base;
the converse of this, where the female flowers are at the summit of the
spike, is much more uncommon. An illustration of this occurrence is
given in the figure (fig. 100). Among the _Coniferae_ numerous instances
have been recorded of the presence of male and female flowers on the
same spike, thus Mr. now Professor Alexander Dickson exhibited at the
Botanical Society of Edinburgh in July, 1860, some malformed cones of
_Abies excelsa_, in which the inferior part of the axis was covered with
stamens, whilst the terminal portion produced bracts and scales like an
ordinary female cone. The stamens of the lower division were serially
continuous with the bracts above. Some of the lower scales of the female
portion were in the axils of the uppermost stamens, which last were
somewhat modified, the anther cells being diminished, whilst the
scale-like crest had become more elongated and pointed, in fact, more or
less resembling the ordinary bracts.[191] Mohl, Schleiden, and A. Braun
have observed similar cones in _Pinus alba_, and Cramer figures and
describes androgynous cones in _Larix microcarpa_. C. A. Meyer ('Bull.
Phys. Math.,' t. x, 1850) also describes some catkins of _Alnus
fruticosa_ which bore male flowers at the