EXOGENS. 243 



Rosals to Saxifragals, and then by way of Brexia to Rhamnads, is but a 

 step. At this point the Gentianal AUiance is entered by way of Hollyworts, 

 and we quit it by moving from Gentianworts into the Solanal Alliance. 

 The Cortusal, Echial, and Bignonial AlHances may be passed without an 



obstacle ; and thus we reach the end of the Perigynous Sub-class. Ges- 



nerworts, in the Bignonial Alliance, fit on to Goodeniads among the Campa- 

 nals of the Epigynous Sub-class ; these join Myrtals, through Myrobalans 

 on the one hand, and Napoleonworts on the other. From Myrtals we pass 

 to the Cactal Alliance, which may be theoretically considered a parietal 

 condition of the former, so near do the Onagrads of the former approach 

 the Loasads of the latter group. This brings us to Barringtoniads and other 

 Orders collected in the Grossal Alliance. The Cinchonals are entered by way 

 of Bilberryworts, and quitted through the Stellate plants, which evidently 

 touch Umbellifers in the Umbellal Alliance. At this point a passage is 

 eflfected into the last Alliance, that of Asarals, by way of Witch Hazels 

 and Sandalworts, till the whole line is finally closed by the Bulhworts. 

 These singular plants, with their ternary flowers, appear to have an incon- 

 testable relationship to Yams among Dictyogens, and thus the circle of 

 affinities eventually returns into itself. 



Each of the Sub-classes consists of Alliances which have also in many 

 instances a strong lateral relation ; so that in order to obtain a clear idea 

 of their mutual correspondence it is necessary to place them side by side as 

 well as in succession. This is very obvious in the following instances : — 



Diclinous. Eyporjynous. Perigynms. Epigynous. 



Urticales, . . . Clienopodales, . . Ficoidales, . . . 



Euphorbiales, . . Malvales, .... Daphnales, 



Menispermales, . Ranales, .... Saxifragales, . . Myrtales. 

 Cuciirbitales, . . Violales, . . • . Bignoniales, . . Campanales. 



{Crescentia.) 



This abundantly shows how hopeless it is to express the real affinities of 

 plants by any other means than a map, or some such contrivance ; and that 

 all sequences will of necessity be inadequate to explain in any considerable 

 degree the position in which natural Orders really stand with relation to 

 each other. 



Alliances of Exogens. 



Sub-Class I. DICLINOUS EXOGENS. 



Flowers S 9 , without any customary tendency to § . 



Amentales. — Flowers in catkins, achlamydeous or monocJdamydeous ; 

 carjyels superior; embryo small, loith Utile or no albumen. 



Urticales. — Flowers scattered, moiiochlamydeous ; carpel single, supe- 

 rior; embryo large, lying in a small quantity ofaMimen. 



Euphorbiales. — Flowers scattered, monodicUamydeous ; carpels consoli- 

 dated, sup)erior; placentce axile; embryo surrounded 

 by abundant albumen. {Albumen occasionally absent.) 



Quern ALES. — Flowers in catTcins, monochlamydeous ; carpels inferior; 

 embryo amygdaloid, v:itTiout albumen. 



Garry ALES. — Floioers monochlaynydeous, sometimes amentaceous ; car- 

 pels inferior ; embryo minute, in a large quantity of 

 albumen. 



2 R 



