344 W. A. Setchell — Classification and Geographical 



The blades are long and narrow and often curved. The surfaces 

 are coarsely reticulated with prominent veins and the margins pro- 

 vided with remote coarse teeth. The fissure appears in the transi- 

 tion-place and divides the blade into two and the stipe almost to 

 the very base so that there is very little of a common stipe left, and 

 this soon disappears or becomes covered with "rootlets,"^ so that we 

 have finally what looks like a group of separate plants in various 

 stages of fission. 



Lessonia, Bory. — There are about six species of this interesting 

 genus, but most of them are rare or ill-represented in herbaria. 



The '* leaves " split at the base into two equal parts each of which 

 develops into a new leaf with it own portion of stipe, and by the 

 repetition of this process the stipe becomes very regularly dichoto- 

 mously branched, and the " leaves " or small blades are borne on the 

 ultimate ramifications. The lower portion of the stipe thickens and 

 becomes fairly stout, even in the smaller species, and in the larger 

 ones it reaches such a size and imitates in its *' rings of growth " so 

 very closely the woody exogens, that the dead trunks thrown up on 

 the beach have been mistaken for logs.^ 



Postelsia, Rupr. — In some of the species of Lessonia^ the "leaves " 

 are borne on very short branches of the stipe and therefore form a 

 more or less compact cluster at the top of the main stipe or "trunk." 

 This is carried still farther in the form, to receive which Ruprecht 

 proposed the genus Postelsia. In adult specimens of this plant, the 

 trunk is hollow and reaches a length of about a foot and a half, 

 with a diameter somewhat less than an inch. On the flattened top 

 of the trunk grows a bunch of from 30-50 leaves which appear to 

 spring directly from it. Each leaf is lanceolate, or somewhat gladi- 

 ate, coarsely wrinkled longitudinally, and provided with a distinct 

 stalk. Most of them are found in the process of dividing which 

 occurs exactly as in Lessonia and Dictyo7ieuron. The stipe of each 

 blade splits to the very base, and so all trace of the branching is 

 lost in the majority of the leaves. Occasionally, however, the split- 

 ting does not continue to the very base of the stalk and this gives 

 rise to a few short branches each bearing six or seven leaves. 



Ruprecht has given excellent figures of adult plants in his " Neue 

 oder unbekannten Pflanzen aus dem nordlichen Theile des stillen 

 Oceans."^ 



1 Cf. Rupr., Mem. Imp. Acad. Sci. St. Petersb., t. 7. p. 80, PL 7, 1852. 



2 Cf. Hooker, Flora Antarctica, Pt. 2, p. 458. 1847. 



3 Mem. Imp. Acad. Sci. St. Petersb., t. 7, PI. 6, 1852. 



