TRICHOMES OF OENOTHERA HYBRIDS AND PARENTAL LINES. 



lengths of these trichomes for the different areas noted. Ventral surface 

 of leaf , between the veins: 37.8, 37.8, 37.8, 39.9, 42.0 42.0, 42.0, 42.0, 42.0, 

 46.2, 46.2, 46.2, 50.4, 50.4, 50.6; on the veins, 37.8, 42.0, 46.2, 50.4, 50.4, 

 54.6, 54.6, 54.6, 54.6, 54.6, 54.6, 63.0, 63.0, 67.2; on the stems: 37.8, 37.8, 

 39.9,39.9,42.0,42.0, 26.2,46.2,46.2, 50.4, 54.6, 54.6,163.0,67.2,67.2. The 

 pear-shaped trichomes were not so abundant on the capsules as elsewhere; 

 9 trichomes from the capsule measured as follows, in /*: 37.8, 46.2, 48.3, 

 50.4, 65.6, 58.8, 58.8, 58.8, 58.8. The averages in length for these hairs 

 are: (l) between the veins, on the lower surface of the leaf, 43.5/*; (2) on 

 the veins, 53.4 p-; (3) on the stem, 54 p-; and (4) on the capsule, 52.5 p-. 



In comparing the relative development of the two kinds of glandular tri- 

 chomes on equivalent areas we find that those on the stem are rather small 

 and that those on the capsule and on the veins of the leaf are relatively 

 large, but the relation of the size of the two trichomes to the given areas 

 is not strictly consistent. For example, the smallest pear-shaped trichomes 

 are to be found between the veins on the lower surface of the leaf, while 

 it is in such areas that the longest club-shaped trichomes occur. This 

 relation is shown in table 1. 



TABLE 1. Relative lengths of the club-shaped and the pear-shaped 

 trichomes of Oenothera lamarckiana. 



OENOTHERA CRUCIATA. 



The three forms of trichomes which are to be found in Oenothera lamarck- 

 iana are present in cruciata also (fig. l). In form and in other charac- 

 ters, the trichomes of cruciata are like those of the other species, only they 

 are consistently smaller. 



The awn-shaped trichomes, upon the lower surface of the leaves and 

 between the veins, are relatively uniform in length and usually straight. 

 The extremes in length which were observed were 71.4 ^ and 131.4 p. On 

 the veins the trichomes are somewhat more variable and range in length 

 between 71.4 /" and 399 p. Mixed with the shorter awn-shaped trichomes 

 there are on the stem numerous giant trichomes of the same character, 

 save as to size. These were seen as long as 1.3 mm. The giant trichomes 

 only, of this general type, were found on the capsule, where they attained a 

 length as great as 1.8 mm. 



