Dichotomous Key to Families

• See list of 21 families in 1a
  GROUP 1

  1a. Plants typically reproducing by spores, seeds and fruits not produced; gametophyte independent of sporophyte; ferns and fern-like plants
• See list of 164 families in 1b
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  1b. Plants typically reproducing by seeds, the seeds borne within a fruit or not; gametophyte dependent on sporophyte; seed plants
  • See list of 3 families in 2a
    GROUP 2

    2a. Plants not producing true flowers; seeds commonly borne in strobili on the surface 
of a scale (embedded in a fleshy aril in Taxus), never enclosed in an ovary; styles and stigmas absent; trees and shrubs with narrow, scale- or needle-like, usually persistent, leaves
  • See list of 161 families in 2b
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    2b. Plants usually producing true flowers; seeds enclosed in an ovary; stigma(s) and usually style(s) present, elevated above the ovary; woody or herbaceous plants with various types of leaves
    • See list of 37 families in 3a
      GROUP 3

      3a. Leaf blades usually parallel-veined (or the plants thalloid in some Araceae); seeds with 1 cotyledon; perianth typically 3- or 6-merous; vascular bundles scattered throughout the stem; secondary growth absent
    • See list of 124 families in 3b
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      3b. Leaf blades usually pinnately veined; seeds with 2 cotyledons; perianth typically 4-, 5-, or more, -merous; vascular bundles arranged in a ring around a central pith; secondary growth absent or present
      • See list of 62 families in 4a
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        4a. Plants definitely woody; secondary growth present (though difficult to detect in some genera)
        • See list of 24 families in 5a
          GROUP 4

          5a. Each node with 2 or more leaves or leaf scars (i.e., leaves opposite or 
whorled)
        • See list of 45 families in 5b
          GROUP 5

          5b. Each node with 1 leaf or leaf scar (i.e., leaves alternate; subopposite at some nodes in some Rhamnus and in Salix purpurea)
      • See list of 85 families in 4b
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        4b. Plants herbaceous or suffrutescent; secondary growth absent
        • See list of 20 families in 6a
          GROUP 6

          6a. Flowers epigynous or partly so (i.e., ovary inferior)
        • See list of 71 families in 6b
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          6b. Flowers hypogynous or perigynous (i.e., ovary superior) or the flowers lacking a perianth
          • See list of 23 families in 7a
            GROUP 7

            7a. Flowers zygomorphic
          • See list of 59 families in 7b
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            7b. Flowers actinomorphic or without a perianth
            • See list of 11 families in 8a
              GROUP 8

              8a. Gynoecium apocarpous, appearing as 2 or more distinct ovaries (i.e., the flower with 2 or more pistils)
            • See list of 56 families in 8b
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              8b. Gynoecium composed of either a single carpel or 2 or more connate carpels, the ovary thereby superficially appearing as 1 (i.e., the flower with 1 pistil)
              • See list of 17 families in 9a
                GROUP 9

                9a. Corolla gamopetalous
              • See list of 43 families in 9b
                GROUP 10

                9b. Corolla apopetalous, absent, or very inconspicuous

Show All Couplets

 Show photos of:   Each photo represents one family in this top.