Mayahuel, or Maya for short, towers over the cactuses, succulents and other plants in the greenhouse’s desert room. Measuring more than 38 feet tall and about 60 years old, Maya’s sturdy quiote — the stalk that grows when the agave is ready to bloom and reproduce — peeks out of an opening in the greenhouse roof. A glass ceiling plate was removed in April when the plant grew 7 inches in a single day.