MORPHOLOG V. 



are exposed on the outer surface. 



Fig. 376- 



Spermatoz <ids of 

 zamia in pollen tube; 

 pg, pollen grain; a, a, 

 spermatozoids. (After 

 Webber.) 



coordinate with them, 

 as follows: 



All the plants of the great group to 

 which the pine belongs have 

 naked seeds. For this reason 

 the name "gymnosperms" 

 has been given to this great 

 group. 



637. Classification of gymno- 

 sperms. The gingko tree has 

 until recently been placed with 

 the pines, yew, etc., in the order 

 Fig. 377. Finales, but the discovery of 



Spermatozoid of za- the spermatozoids in the pollen 



mia showing spiral ... 



row of cilia. (After tube suggests that it is not 



Webber.) closely allied with the Finales, 



and that it represents an order 



Engler arranges the living gymnosperms somewhat 



Class Gymnospermae. 



Order i. Cycadales; family Cycadaceae. Cycas, Zamia, etc. 

 Order 2. Gingkoales; family Gingkoaceae. Gingko. 

 Order 3. Finales (or Coniferae); family i. Taxaceae. Taxus, the common 



yew in the eastern United 

 States, and Torreya, in the 

 western United States, are 

 examples. 



family 2. Pinaceae. Sequoia (redwood of 

 California), firs, spruces, pines, 

 cedars, cypress, etc. 



Order 4. Gnetales. Welwitschia niirabilis, deserts of southwest Africa; 

 Ephedra, deserts of the Mediterranean and of West 

 Asia. Gnetum, climbers (Lianas), from tropical 

 Asia and America. 



