SEEDS TRANSPORTED BY WIND. 
51 
joram, thyme, savory, catmint, skullcap, self-heal, dragon’s 
head, motherwort, and various dry fruits of several 
chickweeds. 
31 . Seed-like fruits moved about by twisting awns. — 
Most of the grains of grasses are invested with glumes, 
or chaff, and a considerable per cent of the chaff has 
awns, some of which are well developed and some poorly 
developed. The distribution of such grasses depends on 
several agents — wind, water, and animals. The chaff and 
awns of all are hygroscopic ; that is, are changed by dif- 
ferences caused by variation of moisture in the air. Sweet 
vernal grass, tall oat grass, holy grass, redtop, animated 
or wild oats, blue-joint, and porcupine grass are among 
them. When mature, the grain and glumes drop off, or 
are pushed off, and go to the ground. When moist, these 
awns untwist and straighten out, but when dry they coil 
up again ; with each change they seem to crawl about on 
the ground and work down to low places or get into all 
sorts of cracks and crevices, where the first rain is likely 
to cover them more or less with earth, after which they 
are ready for growth. 
32 . Grains that bore into sheep or dogs or the sand. — 
Porcupine grass, Stipa spartea, grows in dry soil in the 
northern states, but more particularly on the dry prairies 
of the central portion of the United States. This grass, 
when ripe, has a very bad reputation among ranchmen 
for the annoyance the bearded grain causes them. The 
grains are blown into the stubble among grasses with the 
