52 



BOTANICAL GAZETTE 



[JULY 



Ophioglossum 



4 



ogenic band; remainder of 

 sporangium formed by the 

 cells of the adjacent sterile 

 tissue. 



Helminihostachys 



Boirychium 



xpose 



I outer Similar to the preceding Like preceding but still 

 wall 5-layered and from in origin and development, further restricted to a single 

 primary wall cell (or cells), except that in most species cell in origin. 



3. Sporangia sunken.* 



the entire wall so arises. 

 Sporangia intermediate. 



4. Dehiscence by trans- By longitudinal slit. 



Sporangia generally 

 short-stalked. 



By transverse slit. 



verse slit. 



5. One to three primary 

 sporogenous cells. 



One primary sporoge- 

 nous cell. 



One primary sporoge- 

 nous cell. 



6. Tapetum unusually Cells radially elongatcdj Same as preceding except 

 two-layered and its cells othenvase like preceding. that there are two to four 

 tangentially elongated. ^ layers of radially elongated 



cells. 



w 



7. Nuclei of tapetal plas- Amitosis of these nuclei Amitosis usual and fre- 



modium probably do not probably occurs, 

 increase in number. 



8. Nuclei of plasmodium No increase in size, 

 do not increase in size. 



quent 



Nuclei increase to four 

 times their original size. 



9. Tapetal nuclei persist More persistent than in Less persistent than other 



up to near time of dehis- preceding. 



genera 



cence. 



10. Sporogenous tissue Blocking much more Blocking extremely reg- 



separates into irregular regular. 



Tilar. 



masses. 



II. Division of sporo- 

 genous tissue up to mother 

 cells not wholly simultane- 



Simultaneous division the 



rule. 



ous. 



12. Maiosis in different 



Maiosis in each mother- 



mother cells varies widely in cell independent. 



Division simultaneous in 

 each block of cells. 



spindles. 



rrangement 



13. Spindleextra-nuclear, 



Spindle intra-nuclear. 



14. Chromosomes 100 to Reduced number 40 to No data. 



120 after reduction, 



15. Spindles in all possi- 

 ble positions with reference 

 to one another. 



60, 



" Either in same plane or 

 perpendictilar to one an- 

 other.*' 



3 



