PURE SPECIES AND HYRIDS OF JUG LANS. 



33 



1 form of long secreting trichoma which was found in Juglans nigra 

 ' ially, was not surely determined r this species; if , indeed, it occurs 

 I %/ans regia at all it is rare. 



short secreting trichome is to found on both surfaces of the 



' s, both old and young, although is more abundant on the latter. 



two of the young stages in develi nent of the short trichome were 



f ferved. After separation from the tidermis the next succeeding cell- 



sion cuts of the head-cell from th stalk-cell. When mature the tri- 



me consists of 2 stalk-cells and 4 he -cells ( shown in fig. 8, n to zv). 



The short secreting trichome shows a msiderable variation in size which 



ears to be directly associated witl he position occupied by it. The 



iation is especially noticeable in tl length of the head. Table 12 



istrates the range of variation in len h of head in young and old leaves 



d in stem. 



Table 12.- Measurements of or t secreting trichomes^ 

 Juglans re ia. i th of head. 



The average length of the trichonu from the dorsal surface is 29.2 p, 

 from the ventral surface. 25.2 p. Tl length of the heads of dorsally 

 placed trichomes is also slightly longerthan those of the ventrally placed 

 ones; those of the former average 14. /* and those of the latter is 13.6 ^ 

 (table 13). 



Tabi 1 i ;. Measurements on short treting trichomes^ Juglans regia. 



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