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Key to Lamium

Lamiaceae

Lamium

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1
Corolla purple, pink, or white; anthers with tufts of hairs; bracts absent or present (if present not reflexed).
  2
Perennial, with rhizomes or stolons; corolla 18-35 mm long, the tube curved; leaves all petioled; [section Lamiotypus].
    3
Corolla white; leaves not blotched with white; lower corolla lip with 2-3 teeth on each side; pollen light yellow
 ⇒ Lamium album ssp. album
    3
Corolla pinkish-purple (rarely white); leaves usually marked with white; lower corolla lip with 1 tooth on each side; pollen orange
 ⇒ Lamium maculatum
  2
Annual, lacking rhizomes or stolons; corolla 10-18 (-20) mm long, the tube straight; leaves all petioled or upper leaves sessile and clasping.
    4
Leaves subtending flower clusters sessile; [section Amplexicaule]
 ⇒ Lamium amplexicaule var. amplexicaule
    4
Leaves all petiolate; [section Lamium].
      5
Leaves subtending whorls deeply serrate, with many teeth > 2 mm long; nutlets (2.5-) 2.7-3.0 (-3.3) mm long
 ⇒ Lamium dissectum
      5
Leaves subtending whorls crenate-serrate, with teeth < 2 mm long; nutlets (2.0-) 2.2-2.5 (-2.8) mm long
 ⇒ Lamium purpureum