GNETALES 113 



South Africa ; and Gnetum , with about fifteen species, from the 

 tropics of both hemispheres. 



The important morphological literature of the group may 

 be outlined historically as follows: In 1863 Hooker 1 published 

 an account of Tumboa in an elaborate memoir, which is probably 

 more generally accessible in Eichler's 2 very full review. In 

 1872 Strasburger 3 published the first adequate account of the 

 more recondite morphological features of the group. In 1877 

 Beccari 4 gave an account of the ovulate flowers of Gnetum, and 

 discussed the nature of the floral structures; while in 1879 

 Strasburger 5 extended and . co-ordinated his previous observa- 

 tions. It is chiefly from the two publications of Strasburger that 

 the current accounts of text-books have been derived. In 1881 

 Bower 6 ' 7 published accounts of the embryo of Tumboa ; and in 

 1882 the same author 8 performed a similar service in the case of 

 Gnetum. These two accounts still remain practically the only 

 source of information concerning the embryos of Tumboa and 

 Gnetum. In 1892 Strasburger 9 again discussed the Gnetales, 

 and in the same year Karsten 10 published a preliminary paper 

 upon the genus Gnetum. In 1893 Karsten ll> 12 published two 

 additional papers, in which he modified and extended his pre- 

 vious conclusions. In 1894 and 1895 Jaccard 13 ' 14 published 

 accounts of Epliedra Helvetica, which assisted materially to an 

 understanding of the group. The most recent contribution is 

 that of Lotsy, 15 who has given a very important account of the 

 female gametophyte and fertilization in Gnetum Gnemon. He 

 has also done great service in bringing together the essential 

 features of the scattered literature, and in contrasting the re- 

 sults of different investigators. 



In the following account of Gnetales these variojus authors 

 have been laid under contribution, as we have had no oppor- 

 tunity to examine any properly fixed material. 



I. THE VEGETATIVE ORGANS 



The species of Ephedra are low straggling shrubs, with long- 

 jointed and fluted green steins, and opposite scalelike leaves con- 

 nate into a two-toothed sheath. True foliage leaves are gen- 

 erally lacking, the work of photosynthesis being assumed by the 

 stem, as in the case of the Equisetales, whose stems are very sug- 

 gestive of Ephedra (Fig. 83). 



