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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



[VOL. 10 



Each species and variety of the subgenus Pterodes is described and when- 

 ever possible the type specimen is listed. After the type, a list of the natural 

 occurring hybrids is included. In the citation of specimens, herbarium abbre- 

 viation listed in the third edition of "Index Herbariorum" (Lanjouw and 



Stafleu, 1959) are used. 



GEOGRAPHIC DISTRIBUTION 



In general the family Juncaceae is distributed in the cooler regions of the 

 world and the few species found in the tropics grow in the mountains. The 

 genus Luzula, which is the second largest in the family, also has the same gen- 

 eral distribution. Although the total range of the genus is world-wide, and 

 species are found on all the continents, two of the subgenera are much more 

 restricted in their distribution while the third (subgenus Luzula) is very wide 

 ranging. 



According to Buchenau (1906) the center of distribution of the genus is 

 probably in the mountainous regions of central Asia, and all of the subgenera 

 are represented in this area. The subgenus Anthelaea. which has the most primi- 

 tive morphology (i.e. type of inflorescence), and simplest chromosome pattern 

 (i.e. diploid species), is almost entirely restricted to the temperate zone of the 

 Northern Hemisphere. Of the 15 species recognized by Buchenau (1906) most 

 of these are found in Europe and central Asia with a few species in the islands 

 off the west coast of Africa. The remaining species of this group are found in 

 eastern Asia and North America with one species, Luzula gigantea, extending 

 into South America. 



Of the remaining two subgenera, Pterodes is generally restricted to the 

 Northern Hemisphere with one species, Luzula johnstonii extending into the 

 mountainous regions of northeastern Africa. The origin of this group is prob- 

 ably in central Europe where two species are found with low chromosome num- 

 bers (Nordenskiold, 1957). In addition, one species is found in eastern North 

 America while the other species of this group are represented in Asia with one, 

 L. rufescens, extending into Alaska and northwestern Canada. 



The last subgenus, Luzula, is the only one that has a world-wide distribution. 

 This subgenus has many species in the Northern Hemisphere, with some extend- 

 ing into Central and South America and a few into Africa and New Zealand. 



PHYLOGENY WITHIN THE GENUS LUZULA 



Buchenau (1906) treated the genus Luzula as comprising three subgenera. 

 Of these, he considered the Anthelaea to be the most primitive. He suggested 

 that from this primitive type the other two subgenera (Pterodes and Luzula) 

 diverged independently. He based his conclusions largely on inflorescence types, 

 and suggested that from the open panicle type of inflorescence found in the sub- 

 genus Anthelaea the inflorescence types of the other subgenera can be derived. 

 From this open panicle the simple corymbose inflorescence of the subgenus 

 Pterodes is formed by a suppression of the pedicels and a loss of all but the 

 terminal flower on each of the major branches of the inflorescence. The com- 

 pound corymb found in some members of this subgenus is probably a remnant 

 of the much branched open panicle. Also, the congested inflorescence of the sub- 

 genus Luzula can be formed from the open panicle by a shortening of the pedi- 

 cels until congested spikes are formed on the major branches. A single congested 



