246 Ward . — On Relations between Host and Parasite 
B. s ter ills , L. 
Is common in Europe, the Orient, and North Asia. It is 
an abundant and well-known weed, and one of the earliest 
of our grasses, extremely common in Cambridge, and one of 
our most characteristic hedge species. It is now extensively 
naturalized in Ohio and other parts of America, in Jamaica, 
in Australia, and elsewhere in our Colonies. 
B. sterilis ‘ seed ’ is so like that of B. maximns that one 
can only distinguish them by the size. ‘ Seed ’ 15 x i*5 mm. 
exclusive of paleal teeth (3-4) and awn (24 mm.) The purple 
colour is perhaps more pronounced however, and the steely- 
blue colour which diffuses out on germination seems charac- 
teristic, since no such stain comes from B. maximus , though 
it does from B. tectorum and, to a less extent, B. madritensis. 
Seedlings four days old show a spear 8-10 mm. long, and 
a beautiful steel-blue colour diffuses around into the filter 
paper. 
In a week pot-plants were 5-10 mm. high. The first sheath 
pink, and the spear very narrow. In five days the spears in 
the intermediate pit were 5-10 mm. up. 
Seedlings in the open with 3-4 leaves had the lamina 
8-8*5 cm - x 3-5 mm. There is a distinct keel, running down 
on to the sheath, and about six light lines on either side of 
the midrib. Ridges above, low and rounded, and about three 
show on each side of the sheath-keel. Spreading hairs, 
especially on the upper surface, keel and edges of the blade, 
but mostly on the keel of the sheath. The sheath is split 
at its apex, but complete elsewhere. The right edge rolls 
over the right, and the broad leaves are soon reflexed, and 
tend to twist. 
B. tectorum , L. 
Is native in Europe, North Africa, the Orient, and North 
Asia. It is, like B. sterilis , a weed of poor soil, &c. I found 
it abundant at Stalden, and in some other parts of the Saas 
Valley. It occurs occasionally in England, but only as an 
introduced alien. The ‘seed’ sent me as B. ciliaris, Torr., 
