138 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



8. " Enation " is a word applying to any part of a flower which is 

 developed last, or later than the organ itself which bears it. 



Thus when the flower of the Toadflax (Linaria) has its corolla nearly 

 complete, the spur is added, so that the corolla at first resembles the 

 permanent pouched form of Snapdragon {Antirrhinum), until the pouch 

 elongates into the spur. 



9. When unisexuality appears in plants whose allies of the same 

 order or genus are all or mostly bisexual, it is a legitimate inference that 

 the former condition is a subsequent occurrence. Thus, in the degraded 

 tribe Poteriecz of Bosaccce we find Salad Burnet has two sexes, the 

 upper flowers of the head being female, and the lower ones bisexual 

 or male. 



The causes of unisexuality from bisexuality are obscure and may 

 occur anywhere in the orders of flowering plants. 



Before giving a list of classificatory terms in the order of evolution 

 it will be as well to state that the botanists are firmly convinced that 

 the flowerless plants were the forerunners of Gymnosperms or " naked- 

 seeded " orders. Ferns, e.g., appear to have led off to Cycads ; but other 

 groups may have supplied links to existing and extinct Gymnosperms ; 

 but I need not repeat what I have said before, only referring the reader 

 to my paper on the " Making and Unmaking of Flowers." 



We may now tabulate the results hitherto sketched out as representing 

 the probable order of evolution, each group in succession having given 

 rise to the next, though the links may now be wanting. 



Sub-kingdom — Cryptogams. (Ferns and extinct plants.) 

 Class I. — Dicotyledons : — 



Sub-class 

 >> 



Division i. 

 „ ii. 

 iii. 



Sub-div. 1 



? 2 

 Division iv. 



Sub-div. 1 



2 



Division v. 



Class II. — Monocotyledon 

 Division i. 

 Sub-div. 1 



2 . 



Gymnosperms. 



Angiosperms (Amentales) 



Thalamiflora 



DisciflorcB 



Calyciflorce 



Ovary superior 



„ inferior 

 Gamopetalce 

 Ovary superior 



„ inferior 

 Incomplete (except Amentales) 



Hypogyna 



Perianth petaloid and ovary superior 

 Glumiferae (Restiales and Glumales ; 

 degraded forms). 

 Division ii. . . Epigynce 



Perianth petaloid and ovary inferior. 



I will now give details of a theoretical origin of Endogens or Mono- 

 cotyledons from Exogens or Dicotyledons. 



With regard to the number of "aquatic" orders the percentage of 

 those in Monocotyledons is 33, whereas in Dicotyledons it is only 4. 



