346 YOUNGKEN— ON THE MYRICACEAE 



He remarked that the Myricaceae displayed many characters similar 

 to several genera of Piperales and Urticales. 



Further reference to Chevalier's monograph, as well as to those of 

 other writers, will be made in the body of this thesis. 



Comparative Morphology of Seedlings 



The seedlings studied were in part gathered, and in part grown from 

 seeds planted in the greenhouses of the University of Pennsylvania. On 

 June 20th, 1913, we gathered 28 seedhngs of M. Carolinensis and 17 of 

 M. cerifera at Wildwood, N. J. These varied in age from a few months 

 up to 3 or 4 years of growth. On July 26th, 1914, we collected 15 seed- 

 lings of M. Carolinensis and 10 of the hybrid M. cerifera x M. Carolinensis, 

 these ranging from 1 to 4 years of age. On March 21st, 1915, we gathered 

 15 seedlings of M. hybrid at Palermo, N. J. Seeds of M. Gale, M. cerifera, 

 M. Carolinensis, and M. cerifera x M. Carolinensis {M. Macfarlanei) 

 were planted in the University of Pennsylvania greenhouses, but up 

 to the present writing only those of M. cerifera have germinated. All 

 of the seedlings collected possessed coralloid clusters of tubercles attached 

 for the greater part to the rootlets coming off from the primary root, but 

 occasionally attached directly to the primary root axis. Examination 

 of 1 1 seedling root systems of M. cerifera grown from seed under artificial 

 conditions revealed the presence of tubercles on all but one. 



Gross Structure of Seedlings 



Myrica cerifera, L 



(Plate 81. Fig. 1) 



Primary root, long, flexuose and tapering with numerous slender 

 lateral rootlets, many of which are furnished with tubercles. 



Hypocotyl, terete, glabrous, red, somewhat curved in its lower portion 

 and becoming woody very early. 



Cotyledons, sessile, glabrous, obovate, opposite, slightly emarginate 

 at apex, clasping at the base, 5.5 mm. long x 4 mm. wide, with a distinct 

 mid-rib, venation pinnate-reticulate. 



Epicotyl, erect, terete excepting toward the apex where it becomes 

 triangular, brownish-red to green yellow and red, hairy, glandular, soon 

 becoming woody; first internode 6 mm. long; second 2 to 2.5 mm.; third 

 6 mm. 



Leaves, simple, cauline or ramal, first and second pairs opposite, the 

 rest alternate, petiolate, alternately pinnately nerved, the lower ones 



