A TAXONOMIC STUDY OF SETARIA ITALICA AND ITS 
IMMEDIATE ALLIES 
F. Tracy Hubbard 
This paper deals with those species of Setaria grouped by Ascherson 
and Graebner, Syn. Mitteleur. Fl. 2^: 74 (1899) under their super- 
species Panicum viride (that is S. verticillata, S. viridis including S. 
amhigua and S. italica) and joined by Kuntze, Rev. Gen. 2: 767, 768 
(1891) to form his Chamaeraphis italica. The study was undertaken 
with a view to determine what S. italica var. germaniccc really was, as 
material of various forms was passing under that name and it gradually 
involved a careful examination of the whole group, — especially of S. 
viridis and S. italica since the old line of separation of these species 
did not hold good. S. verticillata separated itself readily when con- 
fined to those specimens with retrorsely barbed setae. 
Some recent authors have reduced 5. italica to a variety or sub- 
species of S. viridis, — for example Ascherson and Graebner, Syn. 
Mitteleur. Fl. 2^: 77 (1899), as Panicum viride B. P. italicum and 
Briquet, Prodr. Fl. Corse i: 68 (1910), as Setaria viridis subsp. italica. 
This is readily understandable when we consider that length of panicle 
and size of spikelet, the key characters commonly employed to separate 
the two species, entirely fail to do so as these characters frequently 
overlap very strongly, though they hold good in the average specimens. 
Generally, the panicle of 5. viridis is said to range up to 8.5 cm. in 
length while the length of spikelet is given as about 2 mm. Careful 
study of the material at hand with measurements of every specimen 
examined, shows a range of panicle dimensions from i to 15 cm. long 
by 4 to 14 mm. in diameter. The spikelets range from 1.8 to 2.7, 
commonly 2.2 to 2.5 mm. long. S. italica, on the other hand, is said 
to have a panicle from 10 to 20 cm. long and spikelets about 3 mm. 
long. My measurements show that in the denser, more spike-like 
forms, — grouped by Alefeld, Landw. Fl. 315 (1866), in his Sect. 
Moharium and best represented by subvar. germanica of this paper, — 
the panicle may be as short as i cm. and not more than 7 mm. in 
diameter while the spikelets of the whole species vary in length from 
2 to 3.2, more commonly 2.6 to 3 mm. 
169 
