THE FLORAL SHOOT. 425 



marsh-mallow, etc. UTien they are united by their filaments in 

 two groups, they are diadelphous (two brotherhoods), as in the 

 pea and most members of the pea family. In most species of 

 St. John's wort (Hypericum), the stamens are united in threes 

 {triadelphoiis). 



815. The carpels are often united. — The pistil is then said to 

 be compound. Where the pistils are consoKdated, usually the 

 adjacent walls coalesce and thus separate the cavity of each 

 ovary. Each cavity in the compound pistil is a locule. In 

 some cases the adjacent walls disappear so that there is one com- 

 mon cavity for the compound f)istil (examples: purslane, chick- 

 weeds, pinks, etc.j. In a few cases there is a false partition 

 (example, in the toothwort and other crucifers). The compound 

 pistil is very often lobed shghtly, so that the different pistils can 

 be discerned. More often the styles or stigmas are distinct, and 

 thus indicate the number of pistils united. 



816. Union of the parts of different series. — While in the 

 buttercup and many other flowers, all the different parts are 

 inserted on the torus or receptacle, in other flowers one series of 

 parts may be joined to another. This is adnadon of parts, or 

 the two or more series are adnale. In the morning glory the 

 stamens are inserted on the inner face of the corolla tube; the 

 same is true in the mint family, and there are many other ex- 

 amples. The insertion of parts, whether free or adnate, is usually 

 spoken of in reference to their relation to the pistil. Thus, 

 in the buttercup the floral envelopes and stamens are all free 

 and hypogynoiis they are below the pistil. The pistil in this 

 case is superior. In the cherry, pear, etc., the petals and stamens 

 are borne on the edge of the more or less elevated tube of the 

 calvx, and are said to be perigynous, i.e., around the pistil. 

 In the cranberry, huckleberry, etc., the calyx is for the most 

 part united with the wall of the ovary with the short calyx limbs 

 projecting from the upper surface. The petals and stamens 

 are inserted on the edge of the calyx above the ovary; they are, 

 therefore, cpigynous, and the ovary Ijeing under the calyx, as 

 it were, is injerior. 



