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 bears all three types (fig:, l). These 

 are 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 are 

 unicellular. 



Fig. 1. — a to d, Oenothera lamarckiana; etog, 0.cruciata;htoj, O. la- 

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

 (X S35); 6, club-shaped trichome from the veins, lower leaf-surface 

 (X 535); c, awn-shaped trichome from ventral surface of leaf, be- 

 tween veins (X 84); d, pear-shaped trichomes from ventral surface 

 of leaf, between veins (X362); 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 stem (X362); A, giant awn-shaped trichome from 

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

 (X 535); j, club-shaped trichome Irom 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 /" 

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

 tween 200 /^ and 1.00 mm._ 



