CLASSIFICATION OF THALLOPHYTES. 605 



Though the grouping of Dicotyledons (according to the characters of the 

 perianth) into Monochlamydese ( = Apetalse), Gamopetalae ( = Monopetalse), and Poly- 

 petalae ( = Dialypetal^), is very generally recognized to be an unnatural one, it is 

 no easy task to replace it by a better one. The families belonging to the great 

 group Dicotyledons show the most multifarious relations to one another. An 

 arrangement, based on the assumption that these families have been developed one 

 from another, is not discoverable; whilst an arrangement in linear series is as 

 unnatural as one resembling a tree with its branches. Very appropriate was 

 Linnasus's comparison of the limitations of these families with the dovetailing of 

 the frontiers of countries on a map. One family stands in touch with two, another 

 with three, others again with four or more allied families. This contact or rela- 

 tionship occurs on the most various sides. Some families are extremely large and 

 comprehensive, others relatively small, and, as it were, jammed in between them; 

 whilst others resemble scattered islands off the coast of a continent. 



Well worthy of consideration is the system of Alexander Braun,i published in 

 1864 in Ascherson's Flora der Provinz Brandenburg. Though the division of 

 Dicotyledons into Apetalee, Sympetalse, and Eleutheropetalse suggests at first sight 

 the classifications of de Jussieu and Endlicher, there is a diiFerence, and an important 

 one. A large number of the families included by the older Botanists in the Apetalee 

 are here placed in the Eleutheropetalae. With the Eleutheropetalse are ranked 

 those plants " in which calyx and corolla are typically present, the latter consisting 

 of separate petals ". They are ranged in 24 Alliances or Cohorts — Hydropeltidinse, 

 Polycarpicae, Rhceadinse, Parietales, Passiflorinse, Guttiferse, Lamprophyllee, Hes- 

 perides, Frangulinse, .^sculinse, Terebinthinse, Gruinales, Columniferse, Urticinse, 

 Iricoccse, Caryophyllinse, Saxifraginse, Juliflorse, Umbelliflorse, Myrtiflorse, Thy- 

 melseinse, Santalinse, Rosiflorse, Leguminosse. In recent times we have the systems 

 of Eichler and Engler. They follow the lines laid down by Alexander Braun, but, 

 carrying his method further, the group Apetalse (or Monochlamydeae) is entirely 

 abolished, its members being referred in part to the Sympetalae, and in part to the 

 Eleutheropetalse ( = Archichlamydese of Engler). 



During the last fifty years our knowledge of the Cryptogams constituting the 

 group Thallophyta (founded by Endlicher, cf. foot-note, p. 604) has increased by 

 leaps and bounds. Several attempts have been made to bring together the results 

 of the various researches upon this group, and to utilize them for classificatory 



1 ALEXANDER BRAUN'S SYSTEM. 

 I. BRYOPHYTA. 



1. Thallodea (Algse, Lichens, and Fungi). 



2. Thallophyllodea (Charaoese, Mosses, and 



Liverworts). 



II. CORMOPHYTA. 



1. Phyllopterides (Perns and Equisetums). 



2. Masohalopterides (Lyoopods). 



3. Hydropterides (Rhizocarps). 



III. ANTHOPHYTA (Flowering Plants). 



A. Gtmnospeem^ (seeds exposed). 



1. Frondosse (Cycads). 



2. Acerosae (Conifers). 



B. Angiospeem^ (seeds in an ovary). 



1. Monocotyledones. 



2. Dicotyledones. 



a. Apetalee. 



6. Sympetalee. 



c. Eleutheropetalse. 



