266 BULLETIN 112, IT. S. DEPARTMENT OF AGRICULTURE. 
Arthraxon Beauv., Ess. Agrost. 111. 1812. Type species, A. 
ciliaris Beauv. This Old World genus is represented in North 
America by A. quartinimius (A. Rich.) Nash, introduced into Ja- 
maica and Guadaloupe, and by A. ciliaris cryptatherus Hack., estab- 
lished in the vicinity of Washington, D. C. The latter is a creeping 
slender grass with thin cordate-lanceolate blades, the inflorescence 
of several slender racemes in a cluster. 
133. Holcus L. 
{Sorghum Pers.) 
Spikelets in pairs, one sessile and fertile, the other pedicellate, 
sterile but well developed, usually staminate, the terminal sessile 
spikelet with two pedicellate spikelets. 
Annual or perennial, tall or moderately tall grasses, with flat 
blades and terminal panicles of 1 to 5 jointed tardily disarticulating 
racemes. Species about six, one Mexican, the others in the Old 
World ; two cultivated or introduced into America, 
Type species: Holms sorghum L. 
Holcus L., Sp. PI. 1047, 1753; Gen. PI., ed. 5, 469. 1754. Linnaeus describes 
seven species, H. sorghum, H. saccharatus, H. halepensis, H. lanatus, H. odo- 
ratus, H. laxus, and H. striatus. The selection of the type species is of 
particular importance in this genus, because it affects the generic name of 
the group containing the cultivated sorghums. The first three of the original 
seven species were segregated from the others in 1763 by Adanson, who applied 
to them the old name sorghum, used by Bauhin and other pre-Linnaean authors 
for the cultivated sorghums. This name was accepted by most of those subse- 
quent authors who recognized the group as a genus distinct from Andropogon, 
and as a subgeneric name by those who held it to be a subgenus of Andropogon. 
Of the remaining four of the original seven species of Holcus all but H. lana- 
tus were early assigned to other genera, leaving H. lanatus in possession of the 
generic name and in effect making this residual species the type of the genus. 
Linnaeus, however, in all the editions of the Genera Plantarum and in the 
Hortus Cliffortianus and the Hortus Upsaliensis used the name Holcus for 
sorghum only. The description and the synonymy in all cases apply only to the 
first three of the seven species included in the Species Plantarum. Moreover, in 
all the editions of the Genera Plantarum Linnaeus cites " Sorgum Mich." While 
Micheli 1 gives no description or figure of the genus, we know from Bauhin 
and others that Sorgum or Sorghum was in common use for the group in 
question. Linnaeus uses the old name Sorghum for the trivial or specific name 
of the first species, and cites Sorghum of Bauhin as a synonym. It is clear 
that the Holcus of Linnaeus is the old Sorghum, the other four diverse species 
(which do not agree with the generic descriptions in any of the works cited), 
evidently being appended for want of a place to put them. According to the 
American Code the genera of Linnseus's Species Plantarum are to be typified 
through citations given in his Genera Plantarum of 1754. The reference to 
Micheli, the use of sorghum as a specific name, and the descriptions all point 
to H. sorghum as the type of the genus Holcus. Holcus lanatus is now referred 
to Notholcus, H. odoratus to Torresia (Hierochloe, Savastana), H. laxus to 
Uniola, and H. striatus to Sacciolepis. By many authors the genus Holcus as 
here understood is included under Andropogon. 
Blumenbachia Koel., Descr. Gram. 28. 1802. A single species, " B. halep- 
pensis." based on " Holcus Haleppensis Linn." is included. 
Sorghum Pers., Syn. PI. 1 : 101. 1805. Four species are included. Holcus 
sorghum L., upon which 8. vulgare Pers. is based, is taken as the type. 
i Nov. Plant. Gen. 35. 1729. 
