AVENA SATJVA. 193 



roots can be frequently found just breaking through 

 the superficial tissues. 



The leaves of oats are sharply distinguished into a 

 sheathing base and a spreading blade. The membra- 

 nous outgrowth, the ligule," which is found at their 

 junction, is common in leaves of this character. 



The flower of oats, like that of the pine, is a meta- 

 morphosed shoot, in which the axis is the stem, and 

 the lateral organs which it bears, leaves. At the base 

 of each spikelet are to be found two glumes or bracts, 

 which thus subtend and more or less completely inclose 

 the whole cluster. At the base of each flower is a 

 single bract, the flowering glume, having the flower in 

 its axil. Concerning the homology of the palet and 

 lodicules much discussion has arisen. Payer 1<s asserts 

 that the palet is a double organ and that the two keels 

 on the palet are primitively distinct. Schacht 17 sees 

 in the palet two parts of a trimerous whorl, of which 

 the anterior part is suppressed. Roper, Wigand, 

 Nageli and others conclude from comparative and 

 developmental researches that the palet is primitively 

 single and takes on its two-keeled condition subse- 

 quently. 18 Hackel 19 believes " that the palea and the 

 pair of lodicules (when two only) are each single, more 

 or less bifid organs, and that they and the third lodi- 

 cule, when present, must be regarded as two or three 



15 For a statement of its homology see Gray, Struct. Botany, pp. 106, 

 211. 



16 Organogenic de la fleur, p. 701. 

 11 Das Mikroskop, 2 Aufl., p. 170. 



18 Cf. Eichler, Bluthendiagramme, p. 120. 



19 Untersuchungen liber die Lodiculae der Graser, Engler's Bot. Jahr- 

 biicher, i, p. 336. 



