176 FIELD CROPS 



Avena sterilis or some other wild form native to southern 

 Europe or northern Africa. Several species of Avena are 

 now found wild in various parts of the world, and one, the 

 common wild oat, Avena fatua, is a serious weed pest in 

 grain fields in the northern United States and in Canada. 

 None of the closely related genera or species is generally 

 cultivated, though velvet grass (Holcus) and tall oat grass 

 (Arrhenatherum) are occasionally sown with other grasses 

 for meadow and pasture purposes. 



221. Botanical Characters. The oat is an annual plant 

 with hollow, jointed stems and fibrous roots. The culms 

 are from 2 to 5 feet in height, the average being about 3J^ 

 feet. The number of culms produced from a single seed is 

 usually from three to seven, though the height of the plant 

 and the number of culms depend very largely on the richness 

 of the soil, the thickness of planting, and the season. The 

 leaves are numerous, lanceolate, 6 to 12 inches long and Y^ 

 to l*/2 inches wide. The base of the leaf, or sheath, clasps 

 the culm for practically the entire length of the internode. 



The flowers are borne in panicles, which are more or 

 less spreading according to the variety. The panicle con- 

 sists of a central stem, or rachis, with from three to five 

 whorls of several small branches each arranged at intervals 

 along it. It is usually from 9 to 12 inches long, and bears 

 from forty to seventy-five spikelets. Each spikelet consists 

 of two or more flowers, of which usually but two are fertile. 

 In some varieties, only one grain reaches full size, though 

 usually two grains develop, the second being smaller than the 

 first. Occasionally the third flower in the spikelet produces 

 a grain, but this is usually too small to be of value. The 

 flowers are enclosed in two thin outer glumes (the chaff), 

 while the reproductive organs of each flower are enclosed in 

 the flowering glume and palea, which later form the hull. 



