256 BOTANICAL GAZETTE. [ October* 



shortest set of stamens is near the base of the corolla tube, 

 and the anthers are not in the same plane, a condition due 

 perhaps to the confined space. A similar variation is, how- 

 ever, found in the other sets of stamens without the same 

 apparent reason. The anthers of all three sets are practi- 

 cally of the same size and color, and might be easily mis- 

 taken for each other when the filaments are removed. As 

 in all truly trimorphic flowers, there are six possible kinds ot 

 pollen and eighteen combinations of pollen with the stigmas. 

 There is a remarkable range in sizes of pollen, but only 

 three prevailing dimensions, as the following table shows in 

 micro-millimeters : 



Drv. Wet. 



T . f Short style, 22.4 X 57.6 — 44.8 X 54.4. 



Long stamens: ^ Mid gty ^ 26.9 X 51.2 - 44.8 X 57.6. 



. T . , . ] Short stvle, 19.2 X 42.6 — 32. X 41.6. 



Mid stamens: j Long ^ 25 g x MJ _ 353 x ^ 



Qk # . J Mid style, 12.8 X 28.8 — 25.6 X 28.8. 



Short stamens: ( LoDg * y £ 12g £ 2g 8 _ 26fl x 28>8< 



By averaging each set, we have : 



Dry. Wet. 



Long stamens, 24.1 X 54.4 — 44.8 X 56. 

 Mid stamens, 22.4 X 46.9 — 33.6 X 43.2. 

 Short stamens, 12.8 X 28.8 — 25.6 X 28.8. 



The measurements of the dry and wet pollen indicate a 

 great change in size and shape when water is added to the 

 dusty pollen as it comes from the dehisced anthers. When 

 dry it has two sutures in the outer coat and resembles a wheat 

 grain in general appearance, but upon the application of water 

 the inner wall enlarges, expands between the two slits in the 

 outer wall, and the grain becomes elliptical or nearly spher- 

 ical. 



Referring to the table of averages it will be seen that the 



measurements for the short stamen pollen are 

 about half of those for the grains from the long- 

 est stamens, and if the size of the smallest 

 pollen, when wet, is represented by 3 X 3? 

 inches those of the largest will be 6 X 7 a . 

 the corresponding relative size of the mid 

 stamen pollen is 4-J- X $h or a half of the sum 

 of the figures for the extreme forms. 

 Three sizes of moist By glancing at the relative sizes of pollen 



Pontederia pollen. in ^^ trimorphic p]ants , as reCO rded by 



Darwin and others, it is found for — 



Ly thrum Salicaria, as 10 — 7 — 6, or 100 to 60. 

 Nessea verticillata, " 13 — 9£— 8£, M 100 M 65. 

 Oxalis speciosa, " 16 —18 —11, " 100 " 69. 

 OialisValidiviana, " 8j- 7 — 6, " 100 " 71. 

 Oralis Kignelli, " 9 — 8$— 7, » 100 u 78. 



