369 
The Stigmas and Pollen of Arisaema.* 
By W. W. RowLee. 
(PLATES 272,'273.) 
The native Araceae fall into two natural groups. One group, 
which Dr. Gray in his Manual calls “the genuine Araceae,” con- 
sists of the genera Arisaema, Peltandraand Calla. The flowers in 
this group have no floral envelopes and are almost always mo- 
noecious or dioecious by the suppression of either the stamens 
or pistil. 
The other group consists of Spathyema, Orontium and Acorus, 
genera composed of plants having complete and perfect flowers. 
This group is much more generalized in its characters than the 
other, and if either deserves to be called the “ genuine Araceae,” 
this, it seems to me, is the one. 
So general is the belief now that the Araceae and the Lemna- 
Ceae present an illustration of specialization by reduction, it need 
hardly be mentioned that Arisaema and its congeners have departed 
farther from the ancestral forms than Calla and its congeners. 
The stamens of Arisaema appear to stand singly upon the spa- 
dix, each stamen representing a single flower. In A. sriphyllum 
this flower really consists of two stamens, the filaments of which 
are grown together so completely as to present the appearance of 
€ single stamen. 
The number of cells in the anther and the vascular strands in 
the filament reveal the fact that cohesion has taken place. The 
anthers are also simple in their structure. See 1, plate (I.). : 
While collecting material for class-work in the spring of 1895, 
T put a spadix of Arisaema triphyllum into alcohol for study. 
Later when sections were made it was found that although the 
anthers had dehisced, nevertheless the anther cavities had con- 
siderable pollen in them, and that many of these pollen grains, still 
remaining in the anther, had developed tubes. In some, the tubes 
were long, in others short, in some they had barely left the grain. — 
The longer ones instead of growing out in a straight path — 
showed a great tendency to grow back upon themselves. The 
appearance at first led me to think that it grew ina close spiral- 
Begum ere a 
* Read before Section G, A. A. A. S., Buffalo meeting, August, 1896. 
