QUERCUS ViRGINIANA. 121 



figured young seedlings of several species of the genus includ- 

 ing: Quercus ilex, 0. pcdunculata, Q. velutina, 0. macrocarpa, 

 (J. plaionoides, and 0. aiistriaca. All of these species behave 

 much alike in germination and there is ver}- httle difference 

 to be noticed in the type of seedling produced. It is a well 

 known fact that in certain genera of plants biological variations 

 often occur in legaid to the relative development of the pri- 

 mary root, the hypocotyl and the cotyledons. It would not 

 therefore, h& surprising if we should find in some of the oaks 

 a departure from the usual type in one or more of these struc- 

 tures. 



In all of the oaks germination takes place by the same 

 method. The cotyledons swell at the point where the petioles 

 join them and thus the outer shell is split open and the coty- 

 ledons forced a])art. The radicle then grows out and the 

 petioles of the cotyledons elongate and carry out the plumule. 

 The j)rimary root in Q. ilex and 0. f^edunculata is "long, woodv, 

 flexuose, tapering, dark colored and wiry." The hypocotyl 

 is ''woody, subterranean, stout, dark colored, flexuose," more 

 or less distinct from the root. The petioles of the cotyledons 

 aie never united into one piece, and their length is about one 

 centimeter. The seedlings of the other species described are 

 very similar to 0. ilex. 



The seedlings of the Q. Girqiniana differs from this tvpe 

 in three important particulars: The primary root is very thick 

 and fleshy, closely resembling that of Hicoria or luglans. The 

 petioles of the cotyledons are not separate but are united 

 throughout their entire length into one terete structure 

 which often reaches a length of Ave or six centimeters. The 

 hvpocot\"l is rudimentary, being only a few millimeters in 

 length. 



The acorns of the Q. Girqiniana germinate immediitelv 

 after maturitv, if conditions are favorable. The petiole is the 

 first structure to elongate ])erceptably, and no matter in what 

 position the acorn is lying it bends in such a wav as to direct 

 the radicle downward. It must therefore l)c jjositivelv geo- 

 tropic, although it would sccni lii'^hlN probable that the stim- 

 ulus is ]:erceived ijy the root tip and transmitted through the 

 radicle to the petioles. '^^ The petiole grows much more rapidly 



♦Copeland, E. B., Studies on the Geotropism of Stems. Bot.Gaz.31: 410-423. 1901. 

 Schutze, Rud., Ueber das geotropische Verhalten des Hypokotyls und des Kotyledons 

 Jahrb. Wiss. Bot. 48: 377-423. 1910. 



