Demerec: Zebra Striped Leaves 



407 



When the seedhngs are old enough, 

 minute yellowish green dots appear as 

 a result of the disappearance of chloro- 

 phyll. These dots are numerous and 

 arranged close together forming regu- 

 lar transverse stripes. Later the dots 

 enlarge in size and become more or less 

 continuous yellowish streaks, the shape 

 and size of which can be seen in Fig. 12. 

 Zebra striped leaves are wavy prob- 

 ably because of unequal growth of the 

 green and the chlorotic tissues. 



Zebra striping is a distinct mature 

 plant character. It is not very promi- 

 nent in some cases, due perhaps to some 

 modifying factor, but is always suffi- 

 ciently developed so that it can be 

 detected by careful examination. In 

 the spring, I was able to distinguish the 

 striping on 4-5 weeks old seedlings, but 

 in the late fall this was not possible on 

 still older seedlings. It is probable 

 that a relatively strong light is neces- 

 sary for the development of zebra 

 striping. 



INHERITANCE OF ZEBRA STRIPING 



Zebra striping is an inherited char- 

 acter. Selfed zebra plants give zebra 

 progeny only. Green plants crossed 

 with zebra give in the Fi generation 

 green plants only. Plants heterozy- 

 gous for zebra crossed with homozy- 

 gous zebra gave 178 green and 152 

 zebra plants, which is fairly close to a 

 1 :1 ratio. From this it might be con- 

 cluded that zebra is a simple mendelian 

 recessive. The data obtained from the 

 F2 generation, however, show in some 

 cases a very low percentage of zebra 

 plants. Six F2 families had a total of 

 115 green and 20 zebra striped plants. 

 Four of these families, however, had 

 92 green and seven zebra plants, 

 which is very nearly a 15:1 ratio. One 

 family, on the contrary, had only 

 17 green to 11 zebra striped plants. 

 Some of Professor Hutchison's pedi- 

 grees also, which are not closely if at 

 all related to the material used in this 

 study, segregated for zebra striping. 

 He found 307 green and 107 zebra 

 plants, practically in 3:1 ratio. At this 

 time the genetical tests are not com- 

 plete enough for final factorial analysis. 

 The only conclusion that can be drawn 

 is that zebra striping is a mendelian 

 character and that it is recessive to 

 green. 



ZEBRA STRIPED LEAF 

 Transverse stripes made up of numerous 

 yellowish dots appear on the leaves of corn in 

 the young plant stage and become more pro- 

 nounced in later stages of development by the 

 enlargement and coalescence of these dots. 

 (Fig. 12.) 



