MORPHOLOGY OF HIGHER PLANTS. 



405 



the pollen grains to adhere, as in CEnothera. The grains may be 

 smooth or variously sculptured ; in most instances the exine is 

 unevenly developed, leaving thin places through which the pollen 

 tubes protrude in germination; these give the appearance of 



FIG. 234. A, Crocus (Spanish saffron) showing two spherical pollen grains, a fragment 

 of stigma with papillae, and fragment of an anther; B, Calendula showing 3 spinose pollen 

 grains and fragment of corolla, the cells of which contain oil-like globules; C, Carthamus 

 (so-called American saffron) showing 2 slightly spinose pollen grains and a fragment of 

 the corolla with brown laticif erous vessels and numerous unicellular hairs. After Weakley. 



grooves when the grains are dry, and the number of grooves is 

 characteristic for different species; in most of the Composite 

 they are three in number ; in the Labiatae there are six, while in 

 Crocus they are wanting (Fig. 234). 



The epidermal cells of the STIGMA are quite characteristic. 



