PARTS OF THE FLOWER 109 



the anthers by two longitudinal slits, through which the 

 powdery yellow pollen may escape. 



4. The gynoecium at the centre of the flower, consisting of 

 an indefinite number of carpels, which are separate from one 

 another (apocarpous), and are seated above the other floral 

 organs on the conical receptacle (superior). Each carpel 

 consists of a lower laterally compressed portion, the ovary, 

 and at the apex of a short curved process (the style) is a rough 

 yellow surface, the stigma. Open one of the carpels carefully, 

 and observe an internal cavity, containing a single round body, 

 the ovule. 



II. Compare the flower of Caltha palustris, the Marsh 

 Marigold. Here the general arrangement of parts will be 

 found to be the same : but note the following points of differ- 

 ence that the calyx is here petaloid, consisting of five or more 

 sepals, the corolla is absent, and the carpels are fewer (five to 

 ten), but of larger size. Slit open one of the carpels along the 

 dorsal side, turn back the flaps, and observe the numerous 

 ovules, attached to the ventral side of the carpel, and arranged 

 in two irregular longitudinal rows. 



III. For comparison with the above, examine the greater 

 Stitchwork (Stellaria holosteci), and note the regular cymose 

 inflorescence (dichasium). The flower is composed of 



1. Calyx, sepals five, polysepalous, inferior. 



2. Corolla, petals five, deeply notched, polypetalous, hypogy- 

 nous. 



3. Andrcecium, stamens ten, polyandrous, or very slightly 

 united at the base, hypogynous. 



4. Gynoecium, carpels three, united or syncarpous, superior : 

 styles and stigmas three. Ovary unilocular, ovules numerous, 

 inserted on the prolongation of the axis (central placentation). 

 This affords an example of cohesion of the carpels. 



Compare the Rose Campion (Lychnis dioicd), which belongs 

 to the same natural order, and shows the same general 

 characters ; but the plants are more or less distinctly uni- 

 sexual, flowers with perfect stamens being borne on some 

 plants, while on others flowers will be found with only the 

 female organs matured : the species is thus dioecious. 



