Cucurbits are monoecious; there are separate male and female blossoms on the same plant. The male flowers tend to open first, followed by the female flowers. It is only when both the male and female flowers are open that pollination can occur.
There is nowhere in the Constitution that says that the Congress can subpoena the President of the U.S. or his people. Congress does however have general subpoena powers, but they are not absolutely clear. There are Supreme Court cases that speak to this. They generally limit this to national security type of issues.
If the president rejects a bill, it takes a two-thirds vote of both houses, which is difficult to achieve, to accomplish a veto override. Other specific powers. The president can call Congress into special session and can adjourn Congress if the House and the Senate cannot agree on a final date. The power to grant pardons for federal crimes (except impeachment) is also given to the president.