Yucatec Ben corresponds to K'iche' Aj, and the sign is glossed as reed and as green maize. In the K'iche' lists Aj is strongly connected with the house, with the cane used in building, and with the growth of the young maize plant, three readings that hold together well once the reed is understood as the growing stalk rather than as a cut stick.
Central Mexico agrees, placing Acatl, reed, in the thirteenth position. Acatl is also one of the four Nahua year bearers of the central Mexican system, alongside Calli, Tecpatl and Tochtli, which is a genuinely different set from either Maya set and a reminder that the year-bearing convention is a regional choice made on top of the shared twenty signs, not a property of the signs themselves.
Ben opens a trecena once in each 260-day round. It is not a Year Bearer in the Classic Maya system, Ik, Manik, Eb and Kaban, nor in the Postclassic Yucatec system, Kan, Muluc, Ix and Kawak, although the sign it corresponds to does bear years in central Mexico, which is precisely the point about conventions.
The thirteenth sign also shows how much of the shared Mesoamerican system is agreement about structure rather than about content. Every tradition that kept the 260-day count kept twenty signs against thirteen numbers, and every tradition that kept a 365-day year restricted its year openings to four signs spaced five apart. The names filled in over that frame vary; the frame does not.