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Agastache mearnsii (Willd.) Woot. & Standl.

Family: Lamiaceae

Description: An herb differing from other Agastache by having attenuate calyx teeth 1/4 the total length of the calyx or more, herbaceous stems, a calyx tube that is straight or nearly so and 2-4 mm in diameter when pressed, with straight and conspicuous costae.

Distribution: Apparently bicentric, but apparently restricted to Mexico, occurring in west-central Chihuahua and adjacent Sonora, and in extreme northwestern Chihuahua.

Plants Seen or Cited: Chihuahua, extreme NW corner, in N end of San Luis Mts., ca. 2 air mi. S of US border, W slope of mts., in canyon at end of ranch road, 9 Oct 1982, Spellenberg & Soreng 6818 (MEXU, NMC); A. mearnsii subsp. pallidiflora: New Mexico, Hidalgo Co., Animas Mts. Sanders (1948, 1949) both TEX (cited in Sanders 1987).

Habitat: Dry canyon bottom with heavy Quercus rugosa, Cupressus, Fraxinus overstory (Spellenberg & Soreng 6818); wooded steep slopes in humus in oak woodlands or in the transitional zone with forest of Pinus ponderosa, 1,700-2,500 m. (Sanders 1987).

Discussion: Martin and Hutchins (1981) record the species from the southwestern portion of New Mexico, mapping it in Grant and Hidalgo counties. This may have derived from Wooton and Standley (1915), the authors of A. mearnsii, who understood the range to include the San Luis Mountains, the Animas Valley, the Burro Mountains, and the Pinos Altos Mountains. Kearney and Peebles (1961) do not note the species for Arizona. Sanders (1987) has no citations for the species from New Mexico that are not intergradient. His maps show the species to be strongly bicentric in Sonora and Chihuahua, Fig. 82 showing the species to barely cross into New Mexico, Fig. 90 showing the species to stop at the international boundary. The only specimen of the species at CIIDIR, NMC, UNM or UTEP is from 2 mi. S of the international boundary in northwestern Chihuahua. Sanders maps a single site from the Animas Mts. in Hidalgo County from which a collection was made that is intergradient between A. mearnsii and A. pallidiflora (Heller) Rydb. Sanders makes no note as to rarity, noting that the species is "scattered on wooded steep slopes." This species is not known in New Mexico in pure form; it is peripheral from the Sierra Madre Occidental where its rarity cannot be determined from available literature or specimens.

Important Literature:

Kearney, T.H., and R.H. Peebles. 1969. Arizona Flora, 2nd ed. (with supplement by J.T. Howell, Elizabeth McClintock, et al.). Univ. California Press, Berkeley. 1085 pp.

Martin, W.C., and C.R. Hutchins. 1981. A Flora of New Mexico, vol. 2. J. Cramer, Vaduz. Pp. 1277-2591.

Sanders, R.W. 1987. Taxonomy of Agastache section Brittonastrum (Lamiaceae-Nepeteae). Systematic Botany Monographs 15:1-92.

Wooton, E.O, and P.C. Standley. 1915. Flora of New Mexico. Contr. U.S. Natl. Herbarium 19: 1-794.

Information Compilied By: Richard Spellenberg 1998

Photo credits in header Peniocereus greggii var. greggii © T. Todsen,
Lepidospartum burgessii © M. Howard, Argemone pleiacantha ssp. pinnatisecta © R. Sivinski
Design: J. Mygatt; Copyright © 1999-2005 New Mexico Rare Plant Technical Council