TRICHOMES OF OENOTHERA HYBRIDS AND PARENTAL LINES. 9 



those on the capsule in the other species, as might be expected from a com- 

 parison of the pear-shaped trichomes. The awn-shaped trichomes are so 

 irreg-ular in their variation that a comparison of them would be meaningfless. 



OENOTHERA LAMARCKIANA X OENOTHERA CRUCIATA. 



The three sorts of trichomes which occur in both pure parents, the awn- 

 shaped, the club-shaped, and the pear-shaped, are to be found in the hybrid 

 also (figf. l). The trichomes, except as to size, are apparently like those 

 of the parents; they are intermediate in size. The figures show the lead- 

 ing characters of the trichomes and a further description of them in this 

 place is unnecessary. 



The awn-shaped trichomes on the ventral surface of the leaf, between the 

 veins, measure from 84.0 j" to 323.0/* long; those on the veins range from 

 84.0 /A to 1073.6 /A in length. Awn-shaped trichomes from the stem are from 

 96.6 /A to 1214.4 /*; those on the capsule are all of the long kind and measure 

 from 915.2 /«. to 1284.8 /* in length. 



The club-shaped trichomes were not seen on the lower surface of the 

 leaves or on the stem, but were abundant on the capsule. The following 

 measurements, in f^, were made of such trichomes from the capsule: 163.8, 

 168.0, 180.6, 193.2, 201.6, 205.8, 210.0, 222.6, 239.4, 243.6. These tri- 

 chomes average 202. 8 f^ in length. 



The pear-shaped trichomes occur on the lower surface of the leaf, on as 

 well as between the veins, on the stem but not on the capsule. Trichomes 

 from the lower surface of the leaf, between the veins, measured as fol- 

 lows, iniJ-: 29.4, 29.4, 29.4, 31.6, 33.6, 33.6, 35.7, 35.7, 37.8, 37.8, 37.8, 

 42.0, 43.2; on the veins, 33.6, 33.6, 35.7, 35.7, 37.8, 37.8, 42.0, 42.0, 42.0. 

 42.0, 44.1, 44.1, 46.2, 50.4. The average length of the former is 34.9 /*, 

 of the latter is 41.3 t^. The following measurements, in /*, were obtained 

 from trichomes on the stem: 33.6, 33.6, 35.7, 35.7, 37.8, 37.8, 42.0, 42.0, 

 42.0, 42.0, 42.0, 44.1, 44.1, 46.2, 50.4. The average length of the pear- 

 shaped trichomes on the stem was found to be 40.6 /*. 



Table 3 gives the relative lengths of the trichomes of Oenothera lamarck- 

 iana X Oenothera cruciata. 



Table ?,.— Relative lengths of club-shaped and pear-shaped trichomes 

 of Oenothera lamarckiana X Oenothera cruciata. 



