284 
in cases when there are three or four the fusion of one 
or both pairs does not take place. 
The axil and nucellus are both lacking vascular supply. 
Gnetales. 
$ 29. Ephedra americana. Humb. et Bonpl. 
Literature: Land (83), Lignier et Tison (88), Thoday 
and Berridge (155). 
Material: Bot. Gard. Groningen. 
The female strobilus of Ephedra stands in the axil of 
the ordinary scale-like leaves, which are decussate on the 
nodes of the main axis. Sometimes the axis bearing the 
cone is branched, as is mostly the case with the stamini- 
ferous ones where are two lateral strobili with a terminal 
one standing between them. The strobilus is formed by an 
axis with, as a rule, three pairs of decussate bracts, the 
uppermost pair of which is fertile only. Fach pair is more 
or less connate, forming three cups above each other, the 
lowest one being small, the upper one very large. Within 
this uppermost cup mostly two ovules are placed, arising 
in the axils of each of the bracts, with the apex of the 
axis between them. Sometimes both ovules are fused with 
their integuments, two nucelli being present within, but 
it also often occurs that only one normal ovule is found, 
standing in the midst of the surrounding fused bracts. 
When ripe the bracts become succulent and of a red 
colour, the composing bracts hardly being to be dis- 
tinguished. In the tribe Alafae, is a greater number of 
opposite standing bracts, which are not fused, and become 
membranous instead of succulent when the seed ripens. 
Thoday and Berridge (155) suggest that it is pro- 
