1286 Rural School Leaflet 



do not always find all the parts present. Often, as in the anemone, one 

 of the sets of the floral envelope is absent, and in that case the remaining 

 set is considered the calyx. In many flowers the stamens are absent ; in 

 that case there occur also on the same plant, or on another plant of the 

 same species, flowers with the pistils absent. In such plants the flowers are 

 said to be unisexual. When pistils and stamens occur in separate flowers 

 on the same plant, we say that the plant is monoecious; and when pistil- 

 late flowers (those without stamens) occur on one plant and staminate 

 flowers (those without pistils) on another, we say that the plant is dioecious. 

 In a perfect flower, the pistils and stamens are in the same flower. 



Another variation that is commonly found has the parts of a series 

 united. When the sepals are united we use the term gamosepalous, and 

 when the petals are united we use the term gamopetalous. A good ex- 

 ample of a gamopetalous flower is the morning-glory. The terms used 

 in case the petals are separate and the sepals are separate are polypetalous 

 and polysepalous, respectively. Besides finding the parts of a series 

 united, we sometimes find the different series united. Different terms 

 are used in these cases, also. When all the series are separate, as in 

 Fig. i, the flower is said to be hypogynous. The flower of a buttercup 

 is hypogynous. It is rather common to find the calyx, corolla, and stamens 

 united, as is shown in Fig. 2. In this case the term perigynous is used. 

 When all the series are united, and the. petals, stamens, and sepals seem 

 to come from the top of the ovary, as in Fig. 3 , we use the term epigynous. 

 The common elderberry is epigynous. In the case of hypogynous flowers 

 we say that the ovary is superior, since it is situated above the other 

 parts. In the case of epigynous flowers we say that the ovary is inferior, 

 because it is situated below the other parts. In case the anthers of the 

 stamens are united, we use the term syngenesious . 



In the foregoing have been given most of the terms used in describing 

 the parts of a single flower. We shall now consider groups of flowers. 

 A flower-bearing part of a plant or the plan of flower arrangement is 

 called the inflorescence. The most simple type of inflorescence is the 

 solitary arrangement, as shown in Fig. 4. Here one flower appears in 

 the axil of the leaf and terminates growth in that direction. 



If the flower is borne close to the main stem, and is without a stem or 

 pedicel of its own, we say that the flower is sessile. This leads to the 

 next form of inflorescence, the spike. In a spike we find a series of flowers 

 that are sessile, or nearly so, arranged along a more or less elongated 

 common axis (Fig. 5). The common blue vervain shows a good example 

 of a spike. A form of spike that is fairly common is the catkin. A catkin 

 is a flexuous, scaly spike, such as we find in poplars, birches, and the 

 like. A catkin is illustrated in Fig. 6. 



