how can cout be undeclared?

[Kirk]

I'm trying to a program ported from linux (redhat7.2 running gcc-2.96RH) to 
freebsd. I have installed gcc-3.0. Most of the compile time errors that I was 
getting while using gcc-2.95 on freebsd have disappeared now that I'm 
compiling with gcc-30. However, there is one that is perplexing me. It is:

tveg.cpp: In member function `void TVeg::dayOut(TDay*)':
tveg.cpp:428: `cout' undeclared (first use this function)
tveg.cpp:428: (Each undeclared identifier is reported only once for each
   function it appears in.).... 

the whole error output is below. 

It is odd that a simple cout (which compiles fine on redhat's 2.96 version) 
is choking here.

Any thoughts?

Thanks in advance,

Kirk


su-2.05a$ make clean
rm *.o *~
su-2.05a$ make pnet
g++30 -c -ansi -g -Wall tday.cpp
g++30 -c -ansi -g -Wall tveg.cpp
tveg.cpp: In member function `void TVeg::dayOut(TDay*)':
tveg.cpp:428: `cout' undeclared (first use this function)
tveg.cpp:428: (Each undeclared identifier is reported only once for each
   function it appears in.)
tveg.cpp: In method `void TVeg::yearOutCN(TDay*)':
tveg.cpp:464: warning: unused variable `double folC'
tveg.cpp:465: warning: unused variable `double totalN'
tveg.cpp:466: warning: unused variable `double totalM'
tveg.cpp: In method `void TVeg::understory(TDay*)':
tveg.cpp:478: warning: unused variable `double mossResp'
tveg.cpp:481: warning: unused variable `double growthResp'
*** Error code 1