Iowa Const. art. III, 2nd div., § 2
The general assembly shall meet in session on the second Monday of January of each year. Upon written request to the presiding officer of each house of the general assembly by two-thirds of the members of each house, the general assembly shall convene in special session. The governor of the state may convene the general assembly by proclamation in the interim.
Repealed and rewritten by Amendment 36 (1974)
Special sessions, see also this codified Iowa Constitution, Art. IV, §11
Referred to in Iowa Code §2B.13