A stamen is opposite each sepal, and in the centre of the flower is the rudiment of a pistil.
The vascular bundles sometimes form a prominent rib, which indicates the middle of the sepal; at other times they form several ribs.
A plane passing through the anterior and posterior sepal and through the floral axis is termed the median plane of the flower; a plane cutting it at right angles, and passing through the lateral sepals, is the lateral plane; whilst the planes which bisect the ?? ?
In Pelargonium the flower is zygomorphic with a spurred posterior sepal and the petals differing in size or shape.
Metamorphosis.It has already been pointed out that each kind of member of the body may present a variety of forms. For example, a stem may be a tree-trunk, or a twining stem, or a tendril, or a thorn, or a creeping rhizome, or a tuber; a leaf may be a green foliage-leaf, or a scale protecting a bud, or a tendril, or a pitcher, or a floral leaf, either sepal, petal, stamen or carpel (sporophyll); a root may be a fibrous root, or a swollen tap-root like that of the beet or the turnip. All these various forms are organs discharging some special function, and are examples of what Wolff called modification, and Goethe metamorphosis.