338 Allgemeines 



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The tirst two chapters are introductory and concern certain 

 principles of floral developnient. These resolve themselves into two 

 broad evolutionary tendencies 1) to Econom}'^ in the Production of 

 Reproductive parts, and 2) to Progressive Adaptation to Insect- Visits. 



Attendant upon these two principles are certain general tenden- 

 cies of progressive evolutionary development in floral structure. 

 The Chief of these are, l) increasing conspicuousness or attractive- 

 ness of the reproductive region, attained either by enlargement of 

 the individual flower, or, by aggregation of flowers into dense 

 inflorescences; 2nd divices of floral structure or habit with direct 

 relation to insect Visits. A fundamental example of such is, 3rd 

 fusion of parts, especially to form tubes, a tendency reflected most 

 generally and extensively in the sympetaly of the group which forms 

 the subject of the present werk. 



In chapter II the Operation of these general tendencies is illustra- 

 ted in a brief review of the ArcJiichlamydeae. It is assumed at the 

 outset that Synipetalae are descended from archichlamydeous ances- 

 tors. Various evolutionär}?- lines are traceable among the Archichla- 

 mydeae; the chief of those concerned in the histor}^ of the Synipe- 

 talae are: the Centrospeymae-\\ne\ the Ranales- Disciflorae-\mt, 

 determined primarily by the tendency to isomer}?- in the androe- 

 cium; and the Ranales-Calycißorae-\\ne, reflecting the tendency to 

 epigyny. There is a prima facie presumption that the Synipetalae 

 are polyphyletic in origin, in the sense that they are not all referable 

 ultimately to a Single sympetalous ancestry. Synipetalae should not 

 exist as a separate group, for they may be divided into several 

 groups, each of which may be associated for classificatory purposes 

 with a natural group of the socalled Avchichlamydeae. Sympetaly 

 has arisen at various points in the lines of descent which are 

 reflected in the several groups of the latter. 



Thus Pentacyclidae (Chap. III) represent the sympetalous descen- 

 dents of Avchichlamydeae in which the economic tendenc}^ to an 

 isomerous androecium has not been fully realized. These, moreover, 

 are referable to at least three separate ancestral Stocks, Ericales to 

 the Geranial Stock, Pvimidales to the Centrospermal Stock, and 

 Ebenales to a Parietalian [Guttiferales) Stock. Two other lines from 

 the hypothetical Apocynal stock may lead respectively to Phmtagi- 

 nales and Jasminales [Oleaceae and Salvadovaceae). The Apocynal 

 plexus gave rise directly to those Tubißome with isomerous androe- 

 cium and regulär flowers — our socalled Transitional Tubiflorae, the 

 Polemoniales of Benth. and Hook.; and this connection is seen with 

 especial clearness in Convolvidaceae. 



The Higher Tubißorae fall naturalh^ into two groups, which 

 are namcd Multiovidatae (Personales) and Diovidatae (Lamiales\ in 

 accordance with the number of ovules associated with each carpel. 

 The latter group reflects a tendency which is well advanced in the 

 Transitional Group, namely, to Schizocarpy --- the association of a 

 separate fruit-body with eacli individual seed: the period of seed- 

 protection is thus extended without prejudice to seed-dispersal. This 

 tendency clearly involves reduction in ovule-number; and this, in 

 the higher Boraginaceae and Diovulatae has become Consta nt — 2 

 per carpel. Fruit specialization is the raain note of advance among 

 Multiovidatae ; it is reflected in the Bignoniaceae-Pedaliaceae-Wne on the 

 one band, and in the Scyophulariaceae-Acanthaceae-Vme on the other. 



Contortae and Tubiflorae, then, form a Single natural group, 

 for they are referable to a Single continuous evolutionary branch- 



