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Key to families | Table of families and genera
Specimen numbers are hyperlinked to records in the Consortium of California Herbaria data view where possible. Taxa are hyperlinked to entries in the Jepson Interchange via the "[Online Interchange]" link.
Perennial herb from rhizomes, glabrous to hairy. Stem: generally ascending to erect, generally branched. Leaf: petioled to sessile; blade elliptic to ovate or lanceolate, toothed to lobed. Inflorescence: head-like in leaf axils or collectively spike- or panicle-like and subtended by bracts. Flower: calyx ± radial, generally 10-veined, lobes 4–5, equal or not; corolla ± 2-lipped, lips generally equal, upper lip notched, lower lip 3-lobed; stamens 4, ± equal, generally exserted, filaments glabrous, anthers segments parallel, distinct. Fruit: nutlets ± ellipsoid, tip rounded.
18 species: temperate. North America, Eurasia. (Latin: ancient name for mint) [Tucker et al. 1980 Taxon 29:233–255] Cult for oils, flavoring, herbs. Hybrids in California generally sterile, spreading from rhizomes.
Unabridged note: Many cultivated and naturalized populations derived from hybridization, generally polyploid, some sterile, reproducing vegetatively.
1. Calyx interior with ring of hairs; vegetative stems decumbent, flowering stems upright ..... M. pulegium
1' Calyx interior glabrous or hairs few, scattered; both vegetative and flowering stems upright
2. Inflorescence generally axillary
3. All leaves ± equal in size, blade generally ovate, generally spicy-scented ..... M. arvensis
3' Leaves reduced in size distally, blade generally linear to lanceolate, generally pennyroyal- or spearmint-scented
4. Leaves gradually reduced distally on stem, generally pennyroyal-scented ..... M. canadensis
4' Leaves greatly reduced distally on stem, generally spearmint-scented (fruit-scented)
5. Calyx 1.5–3 mm, lobes triangular ..... M. ×gracilis
5' Calyx 2.5–4 mm, lobes sharply tapering ..... M. ×smithiana
2' Inflorescence terminal
6. Inflorescence generally head-like, clustered at distal 3–5 nodes
7. Blade generally ovate, generally lavender- and citrus-scented ..... M. aquatica
7' Blade ovate to lanceolate, generally peppermint- or spearmint-scented (lavender and citrus) ..... M. ×piperita
6' Inflorescence spike-like
8. Leaves wrinkled
9. Blade lance-oblong, glabrous (branched-hairy abaxially), spearmint-scented ..... M. spicata (2)
9' Blade ovate, with scattered many-branched hairs abaxially, fruit-scented ..... M. suaveolens
8' Leaves not wrinkled, occasionally deeply veined
10. Blade lanceolate to lance-oblong
11. Blade widest near middle, hairs unbranched; fertile anthers ± 0.3–0.4 mm; generally musty-scented ..... M. longifolia
11' Blade widest near base, occasionally branched-hairy abaxially; fertile anthers ± 0.4–0.5 mm; generally spearmint-scented ..... M. spicata (2)
10' Blade oblong to ovate
12. Calyx ciliate; fertile anthers 4; leaf blade base tapered to ± lobed; corolla 2.5–3.5 mm; Great Central Valley, Central Coast, Transverse Ranges ..... M. ×rotundifolia
12' Calyx generally canescent; fertile anthers generally 0; leaf blade base tapered; corolla 3–4 mm; Transverse Ranges ..... M. ×villosa
Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html [accessed on month, day, year]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
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