GNETALES— WELWITSCHIA 407 



throughout the life of the plant. The cotyledons and leaves are, at 

 first, erect; but, before the end of the first year, the cotyledons begin 

 to droop and the leaves become horizontal (fig. 381). 



In the axil of each cotyledon a bud appears and becomes flatter 

 and broader until the two buds meet, forming a continuous plate, 

 under which the stem apex, now arrested, is buried. Meanwhile, the 

 tissues above and below the base of the leaves grow so that the 

 leaf bases become buried in a deepening groove. 



At the lower part of the hypocotyl, a lateral outgrowth, called the 

 feeder, acts as a haustorium until the food supply of the seed is ex- 

 hausted. 



The times for various stages are given by Pearson as follows: 

 most of the stages in the development of both male and female 

 gametophytes can be secured in January. In 1904, at Haikamchab, 

 there was little fertilization before the end of the second week in 

 January. At Welwitsch, in 1907, the last week in January, fertiHza- 

 tion and proembryos were abundant; and in March, 1909, embryos 

 were more advanced. At Haikamchab on May 10, 1861, Baines 

 collected ripe seeds. So the intraseminal growth of the embryo is less 

 than 4 months. 



