TRICHOMES OF OENOTHERA HYBRIDS AND PARENTAL LINES. 5 



TRICHOMES OF OENOTHERA LAMARCKIANA x OENOTHERA 

 CRUCIATA AND OF THE PARENTAL LINES. 



Three types of trichomes are found in both Oenothera lamarckiana and 

 Oenothera cruciata, and each species hears all three types (fig. l). These 

 arc awn- or awl-shaped, club-shaped, and pear-shaped, and are referred 

 to as such in the following account of them. All of the trichomes arc 

 unicellular. 



Fig. I. a to d, Oenothera lamarckiana; e to g, O. cruciata; h to.?', O. la- 

 marckiana X cruciata. a, pear-shaped trichomes from the stem 

 (X 535); 6, club-shaped trichome from the veins, lower leaf-surface 

 ( 5:55); c, awn-shaped trichome from ventral surface of leaf, be- 

 tween veins ( < 8f ); <l, pear-shaped trichomes from ventral surface 

 of leaf, between veins ( x, 362); e, awn-shaped trichome from be- 

 tween the veins, ventral leaf-surface (X 362); /, pear-shaped tri- 

 chomes from ventral surface of leaf, between veins; g, awn-shaped 

 trichome from stein ( 362); h, giant awn-shaped trichome from 

 capsule ( 84); i, pear-shaped trichomes from ventral leaf-surface 

 (X 535); .?', club-shaped trichome from capsule (X 362). 



The awn-shaped trichomes of the older leaves are lifeless. They vary 

 in length to a marked degree, and in extreme instances range from 71.4 h- 

 to 1.8 mm., although for the most part the differences in length lie be- 

 tween 200 M and 1.00 mm. 



