14 BULLETIN- G22, U. S. DEPARTMENT OF AGRICULTURE. 
and the other naked. Later, the trifurcate character was trans- 
ferred to many forms, until H, v. trifurcatum is noteworthy only as 
the parent form of trifurcate barleys. This illustrates the vital dif- 
ference between the treatment of a group with onl}^ a few representa- 
tives and one with many. The greater the number of forms, the 
fewer are the characters that separate them. 
KEY TO THE VARIETIES. 
Following is the key to the varieties occurring under the four spe- 
cies of barley : 
Hordeum vnlgare. Barleys with three fertile spikelets at each node, the lemmas 
of both central and lateral florets bearing awns or hoods. 
Kernels hulled. 
Lemmas awned. 
Kernels white, blue, or purple 1. pallidum. 
Kernels black 2. nigrum. 
Lemmas hooded. 
Kernels white, blue, or purple 3. Jwrsfordiamim. 
Kernels black 4. atrum. 
Kernels naked. 
Lemmas awned. 
Kernels white, blue, or purple 5. coeleste. 
Kernels black 6. dupUnigrum. 
Lemmas hooded. 
Kernels white, blue, or purple 7. trifurcaUun. 
Kernels black 8. aethiops. 
Hordeum intermedium. Barleys' in which the lateral 
florets are fertile but awnless. 
Kernels hulled. 
Lemma of central floret awned or awnless. 
Kernels white, blue, or purple 9. haxtoni. 
Kernels black 10. mortoni. 
Lemma of central floret hooded. 
Kernels white, blue, or purple 11. suhcorniitum,. 
Kernels black 12.* atricornutum. 
Kernels naked. 
Lemma of central floret awned or awnless. 
Kernels white, blue, or purple 13. midihaxtoni. 
Kernels black 14. nudiynortoni. 
Lemma of central floret hooded. 
Kernels white, blue, or purple 15. cornutum. 
Kernels black 16. subaethiops. 
Hordeum distichon. Barleys in which the lateral florets 
are present but sterile. 
Kernels hulled. 
Lemmas awned or awnless. 
Kernels white, blue, or purple 17. palmeUa. 
Kernels black 18. nigricans. 
Lemmas hooded. 
Kernels white, blue, or purple 19. angustispicatum. 
Kernels black - 20. rimpauL 
