104 



THE BOOK OF NATURE STUDY 



are raised upon a tubular growth, and thus appear to be united. 

 The parts developed from the original outgrowths give rise to 

 the free lobes on the margin of the tubular part of the corolla. 



It is comparatively rare to find the carpels distinct from one 

 another as in the Buttercup. They are usually less numerous 

 than in that flower, and form a single whorl, the number of carpels 

 being the same or smaller than that of the petals or sepals. They 

 may be more or less completely united to form a single pistil. 

 Sometimes only the lower parts are joined, the upper portion of 

 the ovaries as well as the styles and stigmas being separate. 

 Often there is a single ovary from which the free styles project, 

 their number indicating the number of carpels making up the 



ovary. When the union is 

 most complete the styles and 

 stigmas are also joined, and 

 the number of carpels is not 

 distinguishable, or is only indi- 

 cated by the lobing of the 

 stigma (Fig. 55). 



While considering the union 

 of the carpels, attention must 

 be directed to the construction 

 of the ovary and the different 

 positions in which the ovules 

 are borne. When the carpels 

 are separate and distinct, as in the Pea or the Marsh Marigold, it is 

 often easy to see that each corresponds to a leaf bent round so that 

 the margins meet, and thus enclosing a cavity. In such cases 

 the ovules are borne along the united margins, and thus stand in 

 a row along the junction which faces the centre of the flower 

 (Fig. 56, A). The Buttercup has a carpel of this kind, but this con- 

 tains a single ovule only. When joined together to form a single 

 ovary, the latter has often as many chambers as there are carpels, 

 and the position of the ovules in them corresponds to their position 

 in the single carpel. Examples of this are the Tulip or Wild 

 Hyacinth, where the pistil is formed of three carpels (Fig. 56, B). 

 In other cases the carpels are joined edge to edge to enclose the 

 single cavity, and then the ovules usually spring from the wall of 



FIG. 55. The pistil of A, Monkshood ; 

 B, Flax ; C, Tobacco Plant. / ovary ; 

 g, style ; , stigma. (From Strasburger's 

 Lehrbuch der Botanik.} 



