560 Mr. Hassall on the Structure of the Pollen Granule. 



Parietosjs. 



Hypericace^, 

 Cylindrical, three-lobed. See fig. 126. 



Hypericum hircinum. 



TuRNERACEiE. 



Pollen granule cylindrical, three-lobed. 

 Turnera elegans. 

 Passiflorace^. 

 Pollen granule spherical, reticulated, and provided with three 

 large valves, first noticed by Purkinje. See fig, 127. 



Passiflora cserulea. P. cserulea, var. racemosa. P. alata. 



Violace^. 

 Pollen granule of an elongated form, four-sided, with square trun- 

 cate extremities ; in water it changes its shape and becomes square 

 in outline, emitting four pollen tubes which issue from fissures con- 

 cealed in the dry granule, one in each of the lines which separate 

 the four sides of the figure. The change of form arises from the 

 approximation of the ends of the granule occasioned by the water 

 which it imbibes, which stretches the membrane, which can only yield 

 in one direction. See fig. 128, 129. 



Viola tricolor. 

 Pollen granule cylindrical, three-lobed. See fig. 130, 131. 

 Viola montana. 



Resedace^. 

 Cylindrical, three-lobed. 



Reseda odorata. 

 Capparidace^. 

 Pollen granule cylindrical, three-lobed. 

 Cleome spinosa. 

 Crucifer^ or Brassicace^e. 

 Pollen granule three-lobed, cylindrical. See fig. 132, 133. 

 Heliophila arabioides. Alyssummaritimum. 



Sinapis alba. Cheiranthus Cheiri. 



Brassica oleracea. C. mutabihs. 



Iberis alba. Matthiola incana. 



Epigynos^. 

 Begoniacejj. 

 Pollen granule same as the preceding. 



Begonia glabraia. 



Ficoide^ or Mesembryace^. 

 Pollen granule cylindrical, three-lobed. 



Mesembryanthemum reflexum. 

 Cactace^.. 

 Pollen granule same as the preceding. 



Opuntia vulgaris. 



