Agastache derives from the Ancient “very much” describing the flower spikes.The genus by Jan Frederik Gronovius in the second edition of his controversial Flora Virginica, based on the specimens and notes of John Clayton. It is a member of subfamily Nepetoideae, which contains a large proportion of the world’s aromatic culinary herbs. Within its subfamily, it belongs to the mint tribe (Mentheae), and therein to the catmint subtribe(Nepetinae). The Nepetinae are robustly supported by cladistic analyses of morphological and sequence data, and were recognized as early.
Agastache nepetoides anatomy; note the curving stamen stalks typical of Agastache sect. Agastache
The closest living relatives of Agastache are believed to be two very different lineages: One is a group of mostly and usually strongly aromatic and rather robust plants, which contains the typical (Dracocephalum), true hyssops (Hyssopus), (Lallemantia), and catnip (Schizonepeta). By contrast, the other lineage unites the largely scentless and low-growing genera Glechoma and Meehania which occur widely across the Holarctic. These three lineages form a tight-knit. it is not resolved with certainty which of the other two lineages is the sister taxon of Agastache, but most data place the aromatic group slightly closer. The genus Agastache seems to have originated as a trans-Beringian of its about 25 million years ago, in the Late Oligocene.
The sister group of this clade is the core of the Nepetinae, the more or less robust and typically aromatic catmints (Nepeta) and their close relatives which occur mainly in and around western Asia. The monotypic and highly distinct Cedronella (Canary balm) of Macaronesia is slightly more distant and seems to be a basal relict within the subtribe. Thus, the last common ancestor of Agastache and its closest relatives probably was an aromatic Eastern perennial or subshrub with verticillasters of bluish-purple flowers – i.e. generally very similar to the present-day Agastache already. The plesiomorphic appearance of Agastache is underscored by the fact that some of its species were formerly placed in Lophanthus and even Cedronella; essentially, the genus as recognized today was distributed piecemeal across the entire Nepetinae. In general, the evolutionary pattern of the subtribe is a mostly eastward expansion from an origin in the southern or the eastern Mediterranean region.
Agastache is divided into two sections, sect. Agastache and sect. Brittonastrum. The former occurs in and around western to central extending across the Bering Strait into . It is characterized by the upper lip of the corolla being small, the stalks of the stamina to protrude widely. Furthermore, two of the four stamina have curving stalks, which cross those of the other pair. Section Brittonastrum is found in and around southwestern , with the highest diversity in the uplands of northern Mexico. Its members have a more well-developed upper corolla lip, under which the stamina run parallel to each other without crossing, and are entirely hidden from view or only protrude with the anthers and stalk tips.