47^ 



PHANEROGAMS. 



(Fig. 330 i>i's), Saponaria, Nerium, Hydrophyllese, &c. When the corolla itself is 

 gamopetalous, the parts of the corona also coalesce, as in Narcissus, where it is 

 very large. 



The complete form of the perianth, especially when its structure is decidedly 

 petaloid and its dimensions considerable, always stands in a definite relation to pol- 

 lination by the aid of insects [or birds] ; and large, brilliantly coloured, odoriferous 

 flowers only occur where the fertilisation is brought about by this means. The 

 purpose of these properties is to attract insects to visit the flowers ; and the in- 

 finitely varied and often wonderful form of the perianth is especially adapted 

 to compel certain positions of the body and certain movements on the part of 

 insects of a definite size and species when searching for the nectar, by which the 

 conveyance of pollen from flower to flower is unintendonally accomplished by 

 them. We shall recur in detail to these physiological questions in the Third Book. 



Fig. 330 I'jzj.— Longitudinal section throu,t,'h the flower of Lychnis /los-'Jcn'ts ; y the elongated portion of the axis 

 between calyx and corolla ; at ligiile of the petals or corona. 



The radial or bilateral symmetry of the perianth is usually associated with that of 

 the other parts of the flower, and will therefore be discussed in connection with it. 



Besides the perianth in the narrower sense which we have hitherto considered, 

 there are often additional envelopes to the separate flowers. In the Malvaceae and 

 some other plants the true calyx appears to be surrounded by a second calyx 

 {Epicalyx or Calyculus), the morphological homology of which, however, varies. 

 In Malope trifida, for example, the three parts of the epicalyx represent a sub-floral 

 bract with its two stipules ; in Kitaibelia vitifolia, the six-parted epicalyx consists 

 (according to Payer) of two such sub-floral leaves with their four stipules. But 

 the epicalyx may be purely illusory from the production of stipular structures by 

 the true sepals, as in Rosa and Potentilla. In Dimithiis Caryophyllus and some 

 other species a kind of epicalyx results from two decussate pairs of small bracts 

 which are found immediately beneath the calyx ; in the terminal flowers of Anemone 

 a whorl of bracts stands at a short distance below the flower, which takes the 

 form in the nearly allied Eranihis hyemalis of a kind of epicalyx \ The epicalyx of 



^ [The garden Clematis known as ' Lucie Lemoine ' possesses a well-marked seven-leaved 

 involucre which has evidently originated from the growth of the axis above the outermost whorl 

 of the multiplied petaloid sepals. — Ed.] 



