83 NATURAL HISTORY OF PLANTS. 



The Polygalacece have been considered so analogous to the 

 Tremandracece by some authors that they have treated the former 

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

 regards the gyneeceum, 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- 

 dracece, and more analogous to that of certain Malyacece [Lasiopetalece') 

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

 the Tremandracece and Polygalacece should be ranged side by side. 

 The latter show an aflBnity with the Geraniacece and Linacece, 

 from which they are distinguished particularly by the anterior keel 

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

 have also, like the lAnacece, the ovules and seeds oitla.e Euphorbiacece, 

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

 idea of these relationships by comparing the Polygalacece, plants 

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

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

 as Tapura, whose resemblance to Moutabea is considerable. It has 

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

 the Polygalacece and the Sapindacece ; 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 Polyga- 

 lacece, and by the direction of the different parts of the ovules when 

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

 with the Xanthophyllece among the Polygalacece, they alone having 

 parietal placentas ; but the Violacece have an isostemonous andro- 

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

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

 Finally the Krameriece by their resupinate flowers have some 

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

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

 we have seen that the Kramerias have a di-carpellary gynseceum 

 which renders all assimilation between the two groups impossible. 



of tte olim'buig species from warm regions. ridaea volubilis and of a Comesperma {Catacoma 



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



Gbueger (in Sot. ^sj'r!. [1850], 161), has indi- t. 10.— Oliy. Stem. Dicot. 6. Several Polygalacete 



cated the peouKarities of the structure of Secu- are cited as not having medullary rays. 



