170 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



ment which brings the cotyledons to a horizontal 

 position in normal plants. 



In some instances the seedlings continued ex- 

 istence after the endosperm and cotyledons had 

 been discarded altogether. The first internode 

 often assumed a length of 5 cm. and had leaves with 

 laminae a centimeter across, with the petioles re- 

 flexed. 



Rumex sp. 



A resting specimen of a Rumex native in the 

 Garden was brought into the dark room December 

 I, 1901. Two weeks later the development of the 

 leaves began and a succession of these organs were 

 formed during the next four months. During my 

 absence from the Garden during February and 

 March, 1902, no observations were recorded, but 

 20 of these organs were seen and the plant 

 was still alive and engaged in sending up leaves, 

 on July 23, 1902, making an additional noteworthy 

 example of a plant capable of extended endurance 

 without the activity of the chlorophyl apparatus. 



The petioles of the etiolated leaves attained a 

 length of 30 to 35 cm. and were flattened on the in- 

 ner, ventral surface. The laminae were represented 

 by thin lamellae of yellowish tissue which extended 

 along the midrib for a distance of 14 to 17 cm. with 

 a width of about a centimeter narrowing toward the 

 base and apex. The petiole appeared to be in a 

 state of elongation throughout its entire length, 

 and the excessive growth of its continuation in the 

 midrib resulted in the rupture of the lamellar struc- 

 tures. In some instances the laminae showed 

 sufficient resistance to set up a marked tension, by 

 which the midrib was held in a curved position some 

 time before giving way. The epidermal cells of 

 the petiole were excessively elongated and some 

 of the normal compound hairs were seen, being 

 also present on the lamina. Perfect and functional 



Fig. 130. Etiolated leaf of Rumex sp. %, actual size. 



