=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 top, and female flowers at the base. [Illustration: FIG. 100.--Spike of _Carex acuta_, with female flowers at the summit.] On the subject of this section the reader may consult A. Braun,. 'Das Individ.,' 1853, p. 65. Caspary, 'De Abietin. flor. fem. struct. morphol.' Schleiden. 'Principles,' English edition, p. 299. Mohl, 'Verm. Schrift.,' p. 45. Meyen in 'Wiegm. Archiv.,' 1838, p. 155. Cramer, 'Bildungsabweich,' p. 4, tab. v, figs. 13-17. Parlatore, 'Ann. Sc. Nat.,' ser. iv, vol. xvi, p. 215, tab. 13A. See also under the head of Prolification, Substitutions, &c.