TRICHOMES OF PAPAVEK HYBRIDS AND PURE SPECIES. 13 



(fig. 2,6). Somewhat away from the tip there are 2 cells in cross-section, 

 still further there are 3 cells, and the number of cells of the cross-section 

 increases as one goes towards its base. At the base the triehome expands 

 suddenly, so that in longitudinal section it is conical. All of the cells of 

 the triehome are elongated in a direction parallel to its longer axis. The 

 increase in length takes place at the tip of the triehome, where new cells are 

 cut off by somewhat oblique walls. Growth in diameter appears to occur 

 by longitudinal divisions of the inner cells, but the exact sequence of these 

 divisions was not studied. The trichomes of the three species are similar 

 in form and size, but they are unlike in quality of roughness. In Pafnu'ci 

 orientate and 1'apa-ccr pilosuin the distal ends of the superficial cells project 

 beyond the general surface of the triehome and turn out at a rather acute 

 angle (fig. 2, c, d, and c) . In Papa-rcr soiiniifcntm, however, these cells did 

 not extend beyond the general surface, with the elTeet that the trieliomes 

 of this species are smooth (fig. 2, a). 



The leaves, stem, and flower-stalk of Pafxircr orientals and of Pa/'aa f 

 pilosuin are well clothed with trichomes; but Papavcr sonuiifcrnin is prac- 

 tically glabrous, as only a few trichomes were observed on the flower-stalk. 

 and none on stem or leaf. 



PAPAVEK SOMN1FEKUM PAI'AVEK OKIENTAI.K. 



The leaves and the stem of the hybrid are well covered with trieliomes, 

 which in size and in form resemble those of Paparn' cricn/a/i'. but in certain 

 regards they are unlike the trichomes of that species. They, also, are dif- 

 ferent from the trieliomes of I^afiarcr soinnifrrniii, and in each instance the 

 variance lies in the character of the peripheral cells. The distal ends of 

 the peripheral cells, which in the seed parent are suppressed, but which 

 project with much regularity in the pollen parent, in the hybrid are ex- 

 tremely variable in their behavior. In some instances they do not project 

 at all, in others the projection is well marked, perhaps accentuated, and 

 frequently a middle condition was noted (fig. 2, /). In this particular, 

 therefore, the hybrid is fairly intermediate and exhibits the influence of 

 both parents. 



PAPAVER SOMNIFERUM X PAPAVER P1LOSUM. 



The hybrid Papaver somnifenim '' Papaver pi lositm is especially well 

 covered with trichomes which closely resemble those of the other Paparcr 

 hybrid studied. That is, in one character, namely, that of the surface of 

 the trichomes, they are intermediate between the pure parents. The pro- 

 jections of the superficial cells are, if anything, even more irregular than 

 in the other hybrid (fig. 2, // and /). In some instances the projections 

 are suppressed entirely, in others they are exaggerated and the triehome 

 has the appearance of bearing branches, but an intermediate condition also 

 occurs. This variation is suggested, but nowise adequately shown, in the 

 accompanying sketches . 



