This work examines the development of ethnobotany, focusing on Mexico in this millennium. How has the discipline grown? What is the relative importance of Spanish? Are there inflection points? How did some select areas develop, and why? Numerical growth was analyzed mainly through Google Scholar queries. Other subjects were treated based on literature and experience of the authors. Spanish continues to be relevant, especially in Mexico. The discipline gained momentum from 2000 onwards because of the social context of the 1990s, the publication of several foundational works, methodological advances, and particularities of Mexican science. The trajectory of ethnobotany is congruent with a model derived from Kuhn’s proposal of cyclical advancement of science: an initial defining stage was followed by a first synthesis, then fast growth of descriptive studies, with a notable recent turn to theory and framework construction. The causes for advances are discussed for three areas (medicinal plants, agriculture, and wild-growing resources). General interest, financing, the consolidation of research groups and the internal organization of institutions have played a role. We highlight important open questions. Ethnobotany is maturing from a descriptive to an analytical stage. However, careful descriptive studies continue to be valuable because the sources of information are in decline, and theory needs an empirical basis. Also, ethnobotany encourages the transmission of knowledge and biocultural memory. It is a key element for integrated sustainability science.