SCALE-LEAVES, FOLIAGE-LEAVES, FLORAL-LEAVES. 645 



only their sheathing portions fused, as, for example, in the Meadow Saffron 

 {Colchicum), or in the much-cultivated "Love in a Mist" {Nigella Damascena), 

 the styles are separate and always fixed at one side of the compartment of the 

 ovary corresponding to them. But when several whorled carpels are completely 

 united with one another as far as the stigma, only a single style is to be seen. 

 This style, which may be considered as a combination of several grooved leaf- 

 stalks, then rises up above the centre of the many-chambered ovary. Just as 

 the leaf-stalk may be frequently absent from foliage-leaves, so sometimes the 

 pistil has no style, and the stigma is sessile or seated immediately upon the ovary. 



The stigma corresponds to the blade portion of a leaf, but is expanded in only a 

 few families of plants, amongst which the irises are the best known. It has to 

 receive and hold the pollen-grains, and its form varies according as to whether these 

 are carried by the wind as flower-dust or are brought to the flowers by insects in 

 cohering masses. In the former case the stigmas are brush-like or feathery, often 

 extended like a cobweb or spread out like a plume; in the latter case, projecting 

 papillae, knobs, ridges and bands are found on them, against which the insects 

 knock ofi" the pollen as they enter the flower. 



If we consider now the functions of the various floral structures rather than 

 the position and succession of the individual members, we arrive at the following 

 result. Of all the structures known as floral-leaves the ovules and pollen-grains 

 {i.e. those parts of the flower on which these structures are produced) alone are 

 indispensable. These portions of the flower, however, must be protected not only 

 during their development and at the moment of fertilization against possible external 

 injurious influences, but the union of pollen-grains with ovules must be brought 

 about by a suitability in the form of the floral -leaves in addition to the mere 

 production of these bodies. In order to be able to fulfil these tasks the floral-leaves 

 which develop ovules or pollen are themselves often suitably equipped and adapted, 

 or a division of labour takes place, so that only one portion of the floral-leaves 

 •develops ovules or pollen, while the other exists for protection and as a means of 

 ensuring fertilization. In many plants, for example, the carpels are not only the 

 bearers of the ovules, but also at the same time their protectors, and by the pecu- 

 liarity of their structure they conduct the pollen to the ovules they bear. In 

 numerous other plants, on the contrary, a division of labour has occurred; the 

 ovules spring from the axis as independent structures, and the carpels proper 

 surround and protect them, and receive the pollen for them, as may be seen typically 

 in the flowers of primulas. In the American Pachysandra, in the Persian Hali- 

 mocnemis, and in many other plants, the stamens produce pollen in coherent 

 masses, but some of them are also provided with allurements for those insects which 

 carry the pollen from flower to flower, and distribute it to the suitable stigmas. 

 A division of labour is met with in most of these plants which have coherent pollen, 

 two, three, or more whorls of stamens are developed, the upper bear anthers and 

 produce pollen, the lower are without pollen, but assume the function of attracting 

 insects and of protecting the upper anther-bearing stamens. Regarded from this 



