2 MINNESOTA BOTANICAL STUDIES. 



The thick, upright, underground stem of Symplocarpus foetidus 

 gives rise to a var)'ing number of inflorescences each year. The 

 winter bud is protected by 2-3 scale leaves. The inflorescences of 

 the season are produced among the sheathing bases of these. Usually 

 a limited number of them (1-3) come to maturity each year while 

 the others remain arrested. Growth and development of the floral 

 organs is very slow as shown by the fact that inflorescences collect- 

 ed in September and which are to blossom out eighteen to twenty 

 months later, already show the spathe and spadix well dif- 

 ferentiated and the rudiments of the flowers laid down (Fig. i, 

 PI. I). In this stage of development the floral branch passes the 

 winter and it is not until the following summer, the one previous 

 to the spring of blossoming, that the ovules are developed. 



In nearly all cases the ovary is one-chambered, with but one ovule 

 in the chamber (Fig. 2, PI. I). This is orthotropous and pendant 

 from the upper part of the cavity. Occasionally two chambers are 

 found with an ovule in each, or more rarely with more than one in 

 each (Fig. 3, PI. I). This is not remarkable in view of the 

 generally inconstant character of the gynaeceum among the Aroids. 



In the fully mature ovule two integuments are present. The out- 

 er one of these very seldom comes more than half ways up the nucel- 

 lus ; the inner either does not cover the end of the nucellus, thereby 

 forming a collar around it (Fig. 22, PI. II), or else it covers it com- 

 pletely, leaving only a narrow micropylar passage (Fig. 33, PI. III). 

 In material collected about the middle of September the inner in- 

 tegument is beginning to form, and the archesporium shows as a 

 somewhat enlarged, densely protoplasmic cell (Fig. 4, PI. I). It is. 

 covered at this stage by a double layer of cells (Fig. 30, PI. III). 



A tapetal cell is cut off from the archesporium by means of a peri- 

 clinal wall and in this cell anticlinal walls soon follow (Fig 4, PI. I 

 and Fig. 31, PI. III). The archesporium, by virtue of a periclinaT 

 division of the tapetal cell, as well as several periclinal divisions of the 

 originally single superficial layer of the nucellus, becomes somewhat 

 deepseated (Fig. 4-5, PI. I). In this stage of development the 

 megasporangium passes the winter season at least in the region 

 around Minneapolis where the material for these observations was: 

 collected. An examination of figures 4 and 5 which are made from 

 material collected respectively in late November and early April,. 



