Trabut: Origin of Cultivated Oats 



79 



THREE TYPES OF CARYOPSES 



Reading from left to right, the first two are of 

 Avena sierilis maxima, the third and fourth 

 of A. sterilis ciilta (the ordinary Algerian 

 oat), while the last, at the extreme right, 

 is A. saliva, the ordinary oat of temperate 

 regions. It will be noted that the cary- 

 opsis of the Algerian variety is as volumi- 

 nous as that of the best races of A .saliva, 

 but a little more lengthened. (Fig. 15). 



the axis which persists above the lower 

 flower, the articulation of the lower 

 flower is more completely obliterated and 

 it is a true rupture which permits it to 

 separate from the glumes. 



DISTINCTIVE characters. 



In the cultivated form of A. sterilis or 

 Algerian oat, the basilar articulation is 

 still very evident. The separation is 

 not as easy in the cultivated race, as in 

 the wild type, but the line of demar- 

 cation and the articular surfaces may 

 easily be recognized. The second flower, 

 which is not articulated in A. sterilis, as 

 in A . fatua, remains adherent for a long 

 time. It does not separate without 

 carrying away at its base the axis itself, 

 which constitutes one of its rnost 

 characteristic points (fig. 14, no. 7). 

 These two characters make it possible 

 to recognize at sight the cultivated oats 

 decended from A. sterilis, races which 

 otherwise are very little different, and 

 do not constitute so varied a series, as 

 do the forms of A. sativa derived from 

 A. fatua. 



The caryopsis of the Algerian oat is 

 as voluminous as that of the best races 

 of A. sativa, but it is a little more 

 lengthened (fig. 15, no. 2). 



Avena sterilis culta has the panicles 

 generally few flowered, of from twenty- 

 five to fifty spikelets; it suckers more 

 than A. sativa, and when cut green, the 



^Of Maison Carre, near Algiers. 



Algerian oat will even give a second crop 

 with rather numerous full panicles. 



The importance of this distinction, 

 besides its interest as indicating the 

 origin of one of our most widely culti- 

 vated plants, rests above all in the very 

 peculiar aptitudes of the races derived 

 from A. sterilis. 



Since 1895, in the oat experiments 

 undertaken at the Botanical Station^ 



This 



A WILD BLACK OAT 



form of the Algerian species is some- 

 times found growing spontaneously. It 

 has been named A. sierilis segelalis f. 

 nigra, and a commercial variety has been 

 produced from it, by selection to reduce 

 the awns. It has been introduced to the 

 United States. (Figure 16). 



