164 FIELD CROtii 



various parts of the world, and one, the common wild oa- , 

 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 vel- 

 vet grass {Holcus) and tall oat grass (Arrhenatherum) are 

 occasionally sown with other grasses for meadow and pasture 

 purposes. 



203. 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 3^ 

 to 13^2 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. 

 The organs of reproduction consist of three stamens with 

 thread-like filaments, tipped with large anthers, and a pistil 

 with two feathery stigmas. The flowers open for only a 

 few hours; fertilization generally takes place before they 



