MORPHOLOGY OF HIGHER PLANTS. 393 



other parts, as in geranium (Fig. 223), where we find five sepals, 

 five petals, ten stamens, and five pistils. 



Flowers are also spoken of as regular or irregular, accord- 

 ing to whether all the parts of a circle are uniform in shape or 

 not; the flowers of geranium are regular, while those of violets 

 are irregular. Regular flowers are also spoken of as actino- 

 MORPHic or RADLVL, and irregular flowers as zygomorphic. The 

 latter are also spoken of as dorsiventral. Dorsiventral flowers 

 either arise as such, as in some of the Leguminosae (Fig. 231), 

 or they may arise as radial flowers and become dorsiventral dur- 

 ing the course of development, as in willow herb (Fig. 224). 



In some flowers the floral envelopes are wanting, and the 

 flowers are said to be naked, as in the willows and grasses. 



Anthotaxy. — The study of the arrangement of flowers on 

 the stem is known as anthotaxy. The flowering axis may bear 

 only a single terminal flower, as in Tulipa ; or the flowers may 

 occur singly in the axils of the leaves, as in Viola canadensis. 

 When, on the other hand, the flowers are borne upon a branch 

 shoot, the internodes of which are more or less condensed, and 

 the leaves smaller and of a more simple structure than the 

 foliaceous leaves, the whole shoot is known as an inflorkscexce, 

 and the leaves are called bracts. The flower thus represents a 

 single unbranched shoot, while the inflorescence represents a 

 branched or ramified shoot. 



The so-called bracts, besides being generally smaller than the 

 leaves proper, are mostly sessile ; they may, however, be green, or 

 membranaceous, or they may exhibit a bright coloration, as in 

 Monarda. 



The stalk of the individual flower is called a pedicel, and 

 may be naked, or bear one or two small bracts, which are called 

 fore-leaves or prophylla. In the monocotyledons there is 

 usually only one fore-leaf, which turns its back to the mother-axis 

 and is frequently two-nerved and two-keeled. In the dicotylerlons 

 there are generally two fore-leaves, which are placed to the right 

 and left of the flower, as in the violets. 



The position of the floral leaves (the sepals, the petals and 

 those of the perianth) depends upon the arrangement of the 

 fore-leaves, so that in most of the monocotyledons, where there 



