Ix] “SEEDS ” 157 
hairs on the lower part. 15x3mm. Awn _ brown, 
twisted and bent, arising from the middle, about 30 mm. 
long. Caryopsis 7 mm. long, hairy at the top and 
distinctly grooved. Rachilla with fine bristles. 
Avena pratensis, L. 
Palea very similar to A. fatua, apex 2—4-toothed or 
bifid, rachilla with stiffer haus. Caryopsis about 5 mm. 
long. 
Avena pubescens, Huds. is a variety of A. pratensis 
found on dry calcareous soils. The caryopsis is very 
narrow, and the rachilla long and feathered with hairs. 
“Seed” shorter than <A. pratensis, 10—13 mm., and 
darker in colour. 
A. fatua is an excellent type of the grasses with dorsal twisted 
and bent awns, and easily examined on account of its size. The 
student will find difficulties with other species of Avena and 
Arrhenatherum. 
Harz says the stiff hairs of Avena bring about the formation of 
intestinal concretions (phytobezoars) and are therefore dangerous to 
domestic animals. 
** = Palea not more than 7T—10 mm. long. 
+  Caryopsis 4—5 mm. long. 
Arrhenatherum avenaceum, Beauy. (Fig. 47). 
Palez papery, ribbed. Awn 13—15 mm., twisted below ; 
palez, with a tuft of hairs below and a ciliate keel, investing 
the fruit: the whole being cylindrical, 8—10 mm. x 1°5. 
Caryopsis 4—5 mm. x 1:2, fusiform, pubescent. Ra- 
chilla hairy. 
The distinctive difference between Avena and Arrhenatherum is 
in the spikelets as a whole. The latter has the lower flower of each 
spikelet male only. Samples contain the “double seeds,” and the 
awn of the upper fertile portion is short (see Fig. 69). 
