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Key to Rosaceae, Key B: Herbs and subshrubs with compound leaves

Rosaceae

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1 Leaves 2- to 3-ternately compound; [tribe Spiraeeae]
1 Leaves 1-compound, either simply pinnately compound or simply palmately compound,
  2 Principal (basalmost) leaves pinnately compound, with (3-) 5-many leaflets (upper stem leaves sometimes 3-foliolate).
    3 Principal leaves with leaflets of markedly disparate shape and size (large leaflets alternating with much smaller leaflets, or a large terminal leaflet and much smaller lateral leaflets).
      4 Lateral leaflets alternating between small and large, the terminal leaflet similar in size and shape to the larger lateral leaflets; terminal leaflet < 3 cm wide; hypanthium either conical or turbinate, armed with hooked bristles, the pistils 2, or hemispheric, the pistils >5.
        5 Leaves glabrous or sparsely pubescent beneath; flowers many in racemes; hypanthium conical or turbinate, armed with hooked bristles, the pistils 2; [tribe Sanguisorbeae]
        5 Leaves silvery sericeous beneath; flowers solitary and axillary; hypanthium hemispheric, the pistils >5; [tribe Potentilleae]
      4 Leaflets variable in size and shape, usually the terminal leaflet much larger than any of the lateral leaflets; terminal leaflet 3-20 cm wide; hypanthium either sauce-r-shaped or hemispheric to conical; pistils 5 or more.
          6 Pistils 5-15, in a circle on a saucer-shaped hypanthium, ripening into upright fruits that resemble follicles but are indehiscent; corolla white or pink; plant 10-20 dm tall; [tribe Ulmarieae]
          6 Pistils many, densely covering the hemispheric to conical hypanthium, ripening into achenes terminated by the persistent style; corolla white, cream, pale yellow, bright yellow, lavender, maroon, or purple; plant 2-10 dm tall; [tribe Colurieae]
    3 Principal leaves with leaflets of generally similar shape and size (the lowest leaflets may be smaller but of similar shape and toothing to the other leaflets).
             7 Stems and leaf rachises and petioles armed with retrorse prickles.
             7 Stems and leaves unarmed.
               8 Foliage and stems viscid-pubescent with brownish hairs; inflorescence a cyme; petals 5, cream-colored; [tribe Potentilleae]
               8 Foliage not viscid-pubescent (if hairy, the hairs not brown or viscid); inflorescence of very many (>100) small flowers in a spike, the rachis hidden by the tightly packed flowers; petals 0; [tribe Sanguisorbeae].
                 9 Leaflets pinnatifid (each leaflet incised nearly to the midvein); stamens 2 or 4 per flower
                 9 Leaflets toothed (the incisions not nearly to the midvein); stamens either 4 or 15-20 per flower (in well-developed, staminate flowers).
                   10 Leaflets 0.8-2 cm long; spike 1-2 cm long, 1-2× as long as broad, globose; stamens 15-20 per flower (in well-developed staminate flowers), the filaments 3-4 mm long; sepals green to pinkish-purple; [cultivated, occasionally escaped]
                   10 Leaflets 3-10 cm long; spike 6-30 cm long, elongate; stamens 4 per flower, the filaments 8-10 mm long; sepals white (sometimes fading greenish); [native]
  2 Principal (basal-most) leaves palmately compound, with 3-7 (-9) leaflets.
                     11 Principal leaves subsessile, 3-foliolate; fruit of follicles; leaves cauline; [tribe Gillenieae]
                     11 Principal leaves distinctly petiolate, the petiole often longer than the leaflets, 3-7 (-9)-foliolate; fruit of achenes; leaves basal and cauline.
                       12 Principal leaves 5-7 (-9)-foliolate; [tribe Potentilleae]
                          13 Petals maroon-colored, shorter than sepals; plants sprawling with horizontal stems bearing rooting nodes; [wetlands from n. PA, n. NJ, sc. IN and sc. OH northward]
                          13 Petals yellow or white, not shorter than sepals; plants trailing or upright, if bearing horiztonal stems with rooting nodes then petals not maroon-colored and plants not in wetlands; [dry habitats, collectively widespread]
                       12 Principal leaves 3-foliolate.
                            14 Plants in flower.
                              15 Petals yellow.
                                16 Pistils 2-6; [tribe Colurieae]
                                16 Pistils (10-) numerous; [tribe Potentilleae]
                              15 Petals white (or slightly pinkish).
                                  17 Calyx lobes not subtended by bractlets; [tribe Rubeae]
                                  17 Calyx lobes subtended by 5 sepaloid bractlets; [tribe Potentilleae].
                                    18 Leaves evenly serrate with many serrations; [widespread]
                                    18 Leaves with 3 (-5) teeth at the apex, otherwise entire
                            14 Plants in fruit (or sterile).
                                       19 Leaflets entire, except for 3 (-5) teeth at the apex; [tribe Potentilleae]
                                       19 Leaflets evenly serrate or crenate, each well-developed leaflet with > 7 teeth.
                                         20 Calyx lobes not subtended by bractlets.
                                           21 Fruit an aggregate of dry, non-adherent achenes; leaflets obtuse at apex; [tribe Colurieae]
                                           21 Fruit an aggregate of fleshy, adherent drupelets; leaflets acuminate at apex; [tribe Rubeae]
                                         20 Calyx lobes subtended by 5 sepaloid bractlets; [tribe Potentilleae].
                                             22 Fruit an aggregate of dry achenes
                                             22 Fruit an accessory fruit of achenes borne on the surface of a fleshy, red receptacle.
                                               23 Fresh fruit reddish inside; leaflets serrate, 2.5-12 cm long; sepaloid bracts narrowing to apex, untoothed
                                               23 Fresh fruit whitish inside; leaflets crenate, 2-4 cm long; sepaloid bracts widest at apex, 3-5-toothed