396 



BOTANICAL GAZETTE 



[may 



are rearranged in table III, to emphasize the modal class for gland 

 number on the petiole and on the leaf base. It will be seen in all 

 the combinations summarized therein that the mode for gland 

 number on the petiole (with only three exceptions) is two, and 

 that on the leaf base it is zero. In other words, the 2-0 condition 

 shown in figs. 1 and n is typical in the plum. Thus it appears 

 that the glands in the plum are too variable, both in position and 

 number, for accurate statements concerning their disposition on 



TABLE III 



Summary 



BORNE ON PETIOLE AND LEAF BASE 



Species or cross 







• 

 2 



M to 



W w 



- 





Q < 



Q 3 

 P 



U W 





Total 

 leaf 



NUMBER 



Abundance (P. triflora) 



Burbank (P. triflora) 



Wolf (P. americana mollis) . . . 

 Abundance X Wolf crosses. . . 



Burbank X Wolf crosses 



P. americana 



P. Besseyi (Sand cherry) .... 

 P. Besseyi crosses 



P. BesseyiXP. hortulana 



miner i (Compass) 



Compass crosses 



P. cerasus 



P. domestica (Shippers' pride) 

 P. domesticaXP. americana. . 



P. pennsylvanica 



jP. Simoni 



1 

 1 



1 



22 



3 



1 



6 



1 

 8 

 1 

 1 



1 

 1 

 1 



400 



400 



400 



15200 



8000 



877 

 400 



800 



400 



1437 

 400 



400 



200 



400 



200 



Glands borne on petiole 



Number 



Mode 



Mean 



409 



2 



I.023 



913 



2 



2.285 



607 



2 



1. 518 



21956 



2 



1.440 



10406 



2 



1.300 



356 



O 



O.406 



407 



2 



1. 018 



3359 



2 



1.866 



428 



2 



1.070 



2019 



2 



1 405 



707 



2 



1.768 



35 



O 



0.088 



89 



O 



0.45S 



554 



2 



1.385 



438 



2 



2.0I9 



Glands borne on leaf 



Number 



189 



333 



39 

 9125 

 5028 



212 



I07 



788 



Mode 



Mean 



212 



SH 

 242 



287 

 112 



8 



33 



o 

 o 

 o 

 o 

 o 

 o 

 o 

 o 



o 

 o 

 o 

 o 

 o 

 o 

 o 



0.473 



0.833 



O.OIO 



0.600 



0.628 



0.242 



0.268 



o 438 



0.530 

 0.357 



0.605 



0.718 



0.560 



0.020 



0.165 



any other basis than that of a statistical analysis. Other char- 

 acteristics of glands, however, may be of distinctive value, and 

 gland disposition may be sufficiently different and characteristic 



value. The outstanding 



taxonomic 



feature of the data on the disposition of glands is that the mode 



th 



j 



mode 



instance is zero. This condition obtains notwithstanding the 

 great diversity in the forms under investigation, and even in the 

 three exceptions to a modal class of two on the petiole, the mode 



