THE CANADIAN nORTICULTUKIST. 



147 



To such small leaves, which are veiy 

 common on the peduncles of flower- 

 clusters, the name bract is given, and if 

 the bracts form a whorl of three or 

 more, the whole is generally called an 

 involucre. There is, then, no green 

 calyx in Hepatica. But we have the 

 whorl of colored leaves corresponding to 

 the petals of the Buttercup. The ques- 

 tion then arises — shall we call these 

 colored leaves sepals or petals ? As 

 they are the outer leaves of the flowers, 

 that would be a reason for calling them 

 sepals, but they are certainly more like 

 ordinary petals than sepals. However, 

 l)0tanists agree to be guided by the first 

 consideration, and call them sepals, and 

 they agree to look upon the Hepatica 

 and all such flowers as have only one 

 of the two outer whorls as being 

 without a corolla. This being under- 

 stood there is no further trouble in the 

 examination of this flower. The colored 

 calyx will be found to be polysepalous ; 

 the stamens are numerous and separate 

 (polyandrous) ; the carpels are nu- 

 merous and separate, the pistil being 

 tlierefore apocarpous ; and each carpel 

 contains one ovule, just as in Bntter- 

 cui>. Note, also, that in this flower, as 

 in the Buttercup, all the parts are at- 

 tached directly to the receptacle. 



The Wallflower blossom may next be 

 examined. Here we have no difficulty 

 in finding the calyx, but there are only 

 four sepals. The corolla consists of four 

 petals. The stamens are six in num- 

 ber, and you will readily discover that 

 two of them are different in length 

 from the other four. The pistil is all 

 in one piece, but if you select an en- 

 larged one from a withered flower, and 

 cut it across with a sharp knife, you 

 will see that it consists of two cells. We 

 have, in fact, in this pistil two carpels 

 grown together, a state of things quite 

 unlike what we found in Buttcu'cup and 

 Hepatica, where the carj)els wen; all 

 separate. We shall often tind instances 



of this growing together, or cohesion, 

 as it is called, of the parts of floral 

 whorls, sometimes sepals cohering, some- 

 times petals, and sometimes stamens. 

 We shall even tind the parts of one 

 whorl growing npon another whorl, 

 such as the petals growing on the calyx, 

 or the stamens growing on the corolla. 

 To distinguish this union of different 

 whorls from the union of parts of the 

 same whorl, we shall speak of the for- 

 mer as adhesion, reserving the term co- 

 hesion exclusively for the latter. 



You will not fail to notice that the- 

 two cells of the ovaiy in Wallflower 

 contain a considerable number of seeds. 



It will be a good plan for you, after 

 studying the Wallflower blossom, to 

 compare its structure with that of 

 Water-Cress, or Shepherd's Purse, or 

 the common 3'ellow Mustard of the 

 flelds. In all these cases you will find 

 so evident a similarity in the form of 

 the flower that you will be pie]:)ared to 

 hear that they all belong to the same 

 natural group of })lants. 



We shall now examine the flower of 

 Geranium, reserving the Dandelion for 

 another occasion. The calyx is of five 

 sepals, as in Buttercup. The corolla, 

 also, is of five separate petals, these 

 being alternate with tlie sepals. The 

 stamens have peculiarities not observed 

 in the other specimens. First notice 

 that the filaments cohere to form a tube 

 at the base. They are in consequence 

 said to be monadelp]t,ous, that is, of one 

 brotherhood. Then yon will observe 

 that there are ten of these filaments, 

 evei'V other one being shorter, so that 

 we have tw^o sets of five each. It is not 

 likely that you will find anthers on all 

 ten of the stamens ; perhaps only on six 

 or seven. The pistil is made up of five 

 united carpels {"'//ncarpoas), and there 

 are clearly five stigmas. These nnite 

 below into a slender column above the 

 ovary ; this column is known as the 

 st'j/le. 



