HORDE “945 
long-awned. When all 3 spikelets of each group are fertile 
the barley is 6-rowed; when 
only the central spikelet is 
fertile the barley is 2-rowed. 
In 4-rowed, or common 
barley, all the spikelets are 
fertile but the lateral rows 
of the opposite sides of the 
head overlap or intermingle 
to form a single row. Sev- 
eral species of Hordeum 
are troublesome weeds. Of 
these may be mentioned H. 
pusillum Nutt., an annual, 
and H. nodosum L., a per- 
ennial, low  short-awned 
species found widely distrib- 
uted in the United States, 
and H.jubatum L. (squirrel- 
tail grass) with long-awned 
soft spikes, a perennial 
found especially westward, 
all 3 native species. Two 
species introduced from 
Europe, H. murinum L. and 
H.Gussoneanum Parl., vari- 
ously known as fox-tail and 
wild barley, are common 
and troublesome on the 
Pacific coast. These are low 
spreading annuals, the first 
with flattened spikes and 
ciliate glumes, the second 
Fic. 62. Hordeum vulgare. Inflores- 
cence (head), X %; cluster of 3 spike- 
lets, and a single floret from the back 
showing the stipiform rachilla, <2. 
