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A. S. HITCHCOCK 
lent to the selection of H. lanatus as the type of Holcus, What should 
have been done, and what is herewith done, was to select H. sorghum 
as the type species, for the following reasons: In the Genera Plan- 
tarum Linnaeus cites, under Holcus, the name "Sorgum Mich.," 
indicating that he was applying the name Holcus to what was called 
Sorgum by Micheli and others of his time, that is, to what we call 
Sorghum. Furthermore and most important, the description of the 
genus Holcus in the Genera Plantarum applies only to the sorghums 
and not to the other 4 species in the Species Plantarum. Therefore 
I have selected Holcus sorghum as the type of Holcus. Holcus then 
becomes the equivalent of Sorghum and replaces that as a generic 
name. This is one of the few cases where a logical selection of the 
type species changes the application of a well-known name among 
economic plants. 
Leersia Swartz, Prod. Veg. Ind. Occ. 21. 1788. Swartz de- 
scribes 3 species. All are equally available as type species. The 
third is chosen because it is the oldest historically, being based on 
Phalaris oryzoides L., the other two being described by Swartz as new. 
Phalaris L. Sp. PI. 44. 1753. Five species are described by 
Linnaeus. The first, P. canariensis, is chosen as the type because 
this is the only one of the five that was known to the older authors as 
Phalaris. 
AiRA L. Sp. PI. 63. 1753. Linnaeus describes 14 species. The 
name w^as first used by Linnaeus in his Flora Lapponica, 1737, where 
he describes four species, these evidently representing his concept of 
Aira. From these four the second (A. caespitosa, usually known as 
Deschampsia caespitosa) is arbitrarily chosen as the type. To select 
the first, A. spicata (Trisetum spicatum), as the type would result in 
changing the application of the name Aira to the genus now called 
Trisetum. It causes less confusion to apply the name Aira to the 
group known as Deschampsia, as is done by many European botanists, 
than to replace the name Trisetum. 
Dactylis L. Sp. PI. 71. 1753. Two species are described: 
D. cynosuroides, now referred to Spartina, and D. glomerata, the orchard 
grass. The second is selected as the type because it was described 
earlier by the author in his Flora Suecica. 
PoA L. Sp. PI. 67. 1753. Linnaeus describes 17 species. From 
the species described in his Flora Lapponica, P. pratensis is selected 
as the type as this is a familiar, widely distributed, and economic 
species. 
