8-3 NATUBAL IIISTORY OF PLAKTS. 



The Pohjgalacem have been considered so analogous to the 

 Tremaiidracecv by some authors that they have treated the former 

 as only an irregular form of the latter. This is true especially as 

 regards the gyntcceum, which has in both groups almost always the 

 same number of cells, with an ovule whose various parts have the 

 same direction; but the perianth is very different in the Treman- 

 draceœ^ and more analogous to that of certain Malyaceœ {Lasiopetaleœ') 

 with which they have also been connected. It appears to us that 

 the Tremandracece and Poli/galacccv should be ranged side by side. 

 The latter show an affinity with the Geraniacccc and Linaceœ^ 

 from which they are distinguished particularly by the anterior keel 

 of their flower and by the organization of the androoeum. They 

 have also, like the Linaccce^ the ovules and seeds of the Bnpkorôiaceœ, 

 and in certain cases the same gynteceum. We shall obtain a good 

 idea of these relationships by comparing the Poli/galaccœ, plants 

 with milky juice, with the irregular flowers of Pedilanfhus on the 

 one hand, and on the other with irregular types of Clmillctieœ^ such 

 as Tupura^ whose resemblance to Moutahea is considerable. It has 

 also been said, and with reason, that there is a great analogy between 

 the Pohjgalaceœ and the Sapindaeeœ ; the latter, however, are easily 

 distinguished by the situation of their disk, exterior to the androceum, 

 the symmetrical form of the latter differing from that of the Poli/gn- 

 lacece^ and by the du'ection of the different parts of the ovules when 

 they are indefinite in number. The Violaceœ could only be confounded 

 with the Xanihopihjlleœ among the Polygalacecv, they alone having 

 parietal placentas ; but the Violaceœ have an isostemonous andro- 

 ceum, dissimilar stamens when the flower is as irregular as in the 

 Xanfhopylleœ ^ and, in a fruit which is often capsular, arillate seeds. 

 Finally the Kramerieœ by their resupinate flowers have some 

 analogy to the Leguminoseœ with which they have often been con- 

 nected ; but the relationship is more in appearance than reality, and 

 we have seen that the Krameyias have a di-carpellary gynteceum 

 which renders all assimilation between the two groups impossible. 



of the climbing species from warm regions. rirhica rohibilis and of a Comt.iperma [Cntacomn 



But few researches have been made in this way. Iiieiilii). See Done, in Arch. Mnn. (1839), i. 205, 



Gruegek {iiiBot. ^l/ï. [1850], 161), has indi- t.\0.—OiA\. Stcm.Dicot.Q. Seyerid Poli/galacerc 



cated tho peculiarities of the structure of Seen- are cited as not having mcdiillary rays. 



