346 W. A. Setchell — Classification and Geographical 



through a process of splitting at the transition-place, yet there is 

 such a fundamental difference in the details of this process from 

 that found among the Lessonese, as to warrant our placing the genus 

 in a subtribe by itself. The latest paper dealing with the morphol- 

 ogy is one by Rosenthal/ At the tip of the frond there is a broad 

 scimitar-shaped blade at the lower, rounded edge of which are 

 several (3-8 or more) parallel slits. These are situated toward the 

 base of the blade and parallel also to the rounded edge. The new 

 leaves are thus formed on one side only and follow one another in 

 fairly rapid succession. In this way also the terminal blade is 

 divided into two parts which are unequal not only in size but in 

 their farther development. The portion cut off by the extension of 

 the lowest slit, becomes an ordinary leaf, more or less lanceolate- 

 ovate in shape, with ciliate-toothed margins and provided with a 

 short stipe and bladder-like expansion at the base. The other por- 

 tion, viz: the terminal blade or leaf repeats this process of cutting 

 off a portion of its base and so on. 



This modification of the process of splitting affects, of course, 

 the general habit of the plant. Instead of a regularly dichotomous 

 stipe with leaflets of the same value, we have a plant whose axis is 

 sympodial and is often unbranched, with leaves in a single row and 

 secuud. Branches arise somewhat irregularly and come into exist- 

 ence when, in the process of splitting, a portion is split off which is 

 equal to the portion left behind. The new blade becomes the ter- 

 minal blade of a branch." 



Alariide^. — Under this tribe it seems best to distino-uish three 

 «ubtribes, the Alarieae, the Egregie?e, and the Ecklonie^. The 

 l^lants of this group possess compound fronds, but these arise, not 

 by any process of splitting as in the Lessoniide?e, but by out- 

 growths from the meristematic region at the transition-place. 



Subtribe 1. Alarieae — This subtribe includes the genera Alaria. 

 and Pterygophora. They are distinguished from the other genera 

 by having the sporophylls situated upon the stipe alone and con- 

 sequently arising upon the stipe-forming portion of the transition- 

 place. 



Pterygophora, Rupr. — Pterygophora Calif or nica, Rupr. is the only 

 representative of this genus. Old plants possess a fairly long (1-2 



' Flora. Bd. Ixxiii, pp. 107-111, Taf. vii-viii, f. 1-3. 

 2 Cf. Rosenthal, loc. cit. pp. 108-109. 



