Tex. Business Organizations Code § 21.408

(a) The certificate of formation or bylaws of a corporation may provide that all or some of the board of directors may be divided into two or three classes that shall include the same or a similar number of directors as each other class and that have staggered terms of office.

(b) The terms of office of the initial directors constituting the first class expire at the first annual meeting of shareholders after the election of those directors. The terms of office of the initial directors constituting the second class expire at the second annual meeting of shareholders after election of those directors. The terms of office of the initial directors constituting the third class, if any, expire at the third annual meeting of shareholders after election of those directors. In each case, the term of office of an initial director is extended until the director's successor is elected and has qualified.

(c) If the certificate of formation or bylaws provide for staggered terms of directors, the shareholders, at each annual meeting, shall elect a number of directors equal to the number of the class of directors whose terms expire at the time of the meeting. The directors elected at an annual meeting shall hold office until the second succeeding annual meeting, if there are two classes, or until the third succeeding annual meeting, if there are three classes.

(d) Unless provided by the certificate of formation or a bylaw adopted by the shareholders, staggered terms for directors must be effected at a meeting of shareholders at which directors are elected. Staggered terms for directors may not be effected if any shareholder has the right to cumulate votes for the election of directors and the board of directors consists of fewer than nine members.

(e) Directors elected by the holders of a class or series of shares or a group of classes or series of shares in accordance with the certificate of formation shall hold office for the terms specified by the certificate of formation.