GNBTALES 



121 



ovule whose integument is produced into a very long tubular 

 projecting micropyle. In fruit the bracts are much modified, 

 becoming red and succulent, or much enlarged and chaffy, and 

 the " perianth " persists and becomes lignified (Fig. 83). 



The development of the megasporangium, as given by Stras- 

 burger ^ for E. campyloda, indicates the usual sequence of 

 events. The archesporium consists of a group of hypodermal 

 cells, which by periclinal division cut off wall cells. The ex- 

 tensive periclinal division of the wall cells organizes them into 

 very regular longitudinal rows (Fig. 89, A), and places the pri- 

 mary sporogenous cells deep within the nucellus. Whether the 

 primary sporogenous cells divide or pass directly into mother 

 cells is not clear, but in any event the mother cells form a deep- 

 seated group variable in number or even reduced to one. 



Tumboa. — In the conelike strobilus the ovulate flowers are 

 axillary, and contain a single ovule, with no trace of stamens. 



Fie, 88.— Gnetum : A, branch with leaves and staminate strobili ; 5, upper portion of 

 a staminate strohilua ; C, a staminate flower ; D, a branch with ovulate strobili ; 

 H, upper portion of an ovulate strobilus ; F, an ovulate flower ; tf, longitudinal sec- 

 tion of an ovulate flower, showing the three envelopes (U,ie,p); A-E, Gnetum 

 laUfoUa; F-G, Gnetum sf.^-A-F after Bltjme, i^ and G after Stkasbdbgek : 

 whole figure from Englee and Prantl's Nat. Pflanzenfam. 



The perianth consists of a single pair of completely united 

 bracts, which close over the ovule like an outer integument and 

 become much flattened laterally, forming two opposite winglike 

 expansions. The integument directly investing the ovule forms 



