12 INTRODUCTORY. 



tube (Fig. 161). When the petals are irregularly united, a 2-lipped 

 or labiate corolla is produced (Fig. 152). 



40. The stamens and pistils are also frequently united. When sta- 

 mens unite by their filaments so as to form a tube, they are monadelphous, 

 (i. e. forming one brotherhood,) as in the Mallow Family (Fig. 45) ; 

 or when, as in the Pulse Family (Fig. 73), they are in two sets, they 

 are diadelphous, (i. e. in two brotherhoods) . The union into three or many 

 parcels is expressed by the terms triadelpkous and polyadelphous. In the 

 large Composite Family, the union takes place by the anthers, when 

 they are syngenesious. 



41. The pistils are oftener united than otherwise, so that what ap- 

 pears to be a simple pistil is frequently made up of several united ones. 

 The union may take place by the ovaries only, the styles remaining 

 wholly or partly free, or it may be so complete that the real nature of 

 the pistil can only be discovered by cutting it across, through the united 

 ovaries, which will generally present as many cells or cavities as there 

 are simple pistils that go to make up the compound one. 



42. The union or consolidation of the parts of different series fre- 

 quently occurs, and this often renders the structure of the flower at first 

 sight rather obscure. When the calyx, corolla and stamens are all free 

 from each other and are evidently inserted below the pistils, they are 

 hypogynous (i. e. under the pistil), as in Fig. 4. When calyx, corolla 

 and stamens cohere together, but are still free from the pistil, so that the 

 latter two appear to be inserted on the former, they are perigynous, (i. e., 

 around the pistil,) as in the Peach and Cherry (Fig. 80). The union 

 often involves the ovary ; in this case, the stamens and corolla appear to 

 be on the calyx, it is still perigynous ; but the union is sometimes so 

 complete that the parts appear to be inserted directly upon the ovary, 

 when they are said to be epigynous ; (i. e., upon the ovary) . These 

 terms are not so much used as formerly, as the condition of the parts is 

 better expressed by saying, calyx half adherent or entirely adherent to 

 the ovary, as the case may be. 



43. The symmetry of the flower (Fig. 38) is broken up either by the 

 suppression or nondevelopment of some parts of a set or by the multi- 

 plication of the parts : but as one or more series usually retains the nor- 

 mal number, there is generally but little difficulty in making out the nu- 

 merical plan upon which the flower is constructed. The number of 

 parts in a whole flower or in a set is expressed by the following terms : 

 binary, if in twos ; ternary., in threes ; quarternary, in fours ; quinary, 

 in fives. Tetramerous, pentamerous, &c., (written 4-merous, 5-merous, 

 &c.) are used to describe flowers with their parts in fours, fives, &c. 



44. Ordinarily the parts of a symmetrical flower alternate ; that is, 

 the petals are placed over the interval between the sepals, the stamens 

 over the interval between the petals and consequently opposite the sepals, 

 and so on. This is to be considered the usual position, unless otherwise 

 stated, in the description of the plant. Exceptions, however, occur, as 



in the Buckthorn and Barberry, where the stamens are placed directly 

 in front of the petals. 



