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Key to Rosaceae

Rosaceae

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1 Herbs or subshrubs (if woody at base, then < 3 dm tall).
(c) Fleming, Gary P.
  2 Leaves compound (at least the lower and better developed)
1 Trees, shrubs, or woody vines (with arching “canes” or climbing, arching, or scrambling stems).
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Key to Rosaceae, Key A: Herbs and subshrubs with simple leaves

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(c) Bradley, Keith
(c) Danielson, Erik
1 Leaves crenate, unlobed; inflorescence of a solitary flower; [tribe Rubeae]
(c) Fuka, Vladimír - CC-BY
  2 Leaves shallowly 7-9-lobed; petals 0; stamens 4.
  2 Leaves 3-lobed; petals 0 or 5; stamens 1 or many.
(c) Shaw, Joey
(c) Radford, Ahles and Bell
    3 Leaf blades 0.3-1.0 cm long and wide, deeply 3-lobed, each lobe further lobed or deeply toothed; petals 0; stamen 1; [tribe Potentilleae]
(c) Kristály, Liszák - CC-BY
(c) Cressler, Alan M.
    3 Leaf blades 3-8 cm long and wide, 3-lobed, each lobe toothed; petals 5; stamens many; [tribe Colurieae]
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Key to Rosaceae, Key B: Herbs and subshrubs with compound leaves

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(c) Bridges, Edwin
1 Leaves 2- to 3-ternately compound; [tribe Spiraeeae]
(c) Hayden, John
(c) Fleming, Gary P.
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.
(c) Danielson, Erik
© Nathan Aaron
        5 Leaves glabrous or sparsely pubescent beneath; flowers many in racemes; hypanthium conical or turbinate, armed with hooked bristles, the pistils 2; [tribe Sanguisorbeae]
(c) Danielson, Erik
        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.
(c) Danielson, Erik
(c) Fleming, Gary P.
          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]
(c) Marcum, Paul
(c) Stuart, Will
          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).
(c) harum.koh - CC-BY-SA
             7 Stems and leaf rachises and petioles armed with retrorse prickles.
(c) Fleming, Gary P.
(c) Marcum, Paul
               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 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]
(c) Ware, Richard & Teresa - CC-BY-NC, permission granted to NCBG
                   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.
(c) Fleming, Gary P.
(c) Fleming, Gary P.
                     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]
(c) Danielson, Erik
(c) Ward, Scott G
                          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]
(c) Fleming, Gary P.
(c) Danielson, Erik
(c) Goldman, Douglas - CC-BY-SA
                          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]
(c) Fleming, Gary P.
                       12 Principal leaves 3-foliolate.
(c) Ware, Richard & Teresa - CC-BY-NC, permission granted to NCBG
                                16 Pistils 2-6; [tribe Colurieae]
(c) Fleming, Gary P.
                                16 Pistils (10-) numerous; [tribe Potentilleae]
(c) Léveillé-Bourret, Étienne - CC-BY-NC, permission granted to NCBG
                                  17 Calyx lobes not subtended by bractlets; [tribe Rubeae]
(c) Ware, Richard & Teresa - CC-BY-NC, permission granted to NCBG
                                  17 Calyx lobes subtended by 5 sepaloid bractlets; [tribe Potentilleae].
(c) Ware, Richard & Teresa - CC-BY-NC, permission granted to NCBG
                                    18 Leaves evenly serrate with many serrations; [widespread]
(c) Fleming, Gary P.
                                       19 Leaflets entire, except for 3 (-5) teeth at the apex; [tribe Potentilleae]
(c) Fleming, Gary P.
                                       19 Leaflets evenly serrate or crenate, each well-developed leaflet with > 7 teeth.
(c) Cressler, Alan M.
                                               23 Fresh fruit reddish inside; leaflets serrate, 2.5-12 cm long; sepaloid bracts narrowing to apex, untoothed
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Key to Rosaceae, Key C: Shrubs and trees with simple leaves

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(c) Weakley, Alan
1 Ovary inferior; fruit indehiscent (pome).
(c) Bradley, Keith
  2 Inflorescence a panicle, of > 25 flowers (6-40 in Pyracantha); leaves leathery, evergreen.
(c) Danielson, Erik
(c) Fleming, Gary P.
    3 Plants armed with thorns
      4 Pomes purplish-black, 7-10 mm in diameter, each with 3-5 seeds; leaves mostly 10-30 cm long
      4 Pomes orangey yellow, (10-) 20-30 mm in diameter, each with 1-2 seeds; leaves (2-) 4-10 cm long
  2 Inflorescence an axillary or terminal raceme, fascicle, cyme, or umbel, of < 20 flowers; leaves herbaceous, deciduous.
(c) Ward, Scott G
        5 Upper surface of leaves bearing dark glandular trichomes along the midrib (most easily seen with a 10× hand lens); shrubs
        5 Upper surface of leaves lacking dark glandular trichomes along the midrib; shrubs and trees.
(c) Fleming, Gary P.
(c) Radford, Ahles and Bell
          6 Ovary and fruit 10-locular; inflorescence a raceme (rarely a fascicle); pome < 1 cm in diameter
          6 Ovary and fruit 5-locular; inflorescence a cyme, umbel, or fascicle (lacking an elongated central axis); pome 0.7-10 cm in diameter.
(c) Lance, Ron
(c) Campos, Aidan
             7 Styles distinct; exocarps (carpels within pericarp) bony and seedlike; trees and shrubs, with thorns
             7 Styles usually connate at base; exocarps leather or papery and easily opened to expose seeds; small trees, unarmed, or armed with sharp spur branches.
(c) Weakley, Alan
(c) Marcum, Paul
               8 Pome globose to ovoid, lacking stone cells; anthers yellow to white; styles connate at the base; leaves blunt to acuminate; [apples and crabapples]
(c) Bradley, Keith
(c) Weakley, Alan
(c) Fleming, Gary P.
               8 Pome globose or pyriform, with stone cells; anthers reddish; styles distinct; leaves acute to acuminate; [pears]
© Scott Ward
1 Ovary superior; fruit dehiscent (aggregate of follicles, or capsule) or indehiscent (drupe, aggregate of drupelets, aggregate of achenes).
(c) Fleming, Gary P.
(c) Fleming, Gary P.
                 9 Leaves opposite; fruit an aggregate of usually 3-5 purple to black drupelets; [tribe Kerrieae]
                 9 Leaves alternate; fruit various (see below; if an aggregate of drupelets, then with >5 drupelets).
(c) Danielson, Erik
                   10 Leaves large, > 10 cm wide, palmately veined, palmately lobed; fruit an aggregate of drupelets; [tribe Rubeae]
                   10 Leaves smaller, < 8 cm wide, pinnately veined, either not lobed or basally pinnately lobed; fruit a drupe, a capsule, an aggregate of follicles, or an aggregate of achenes.
                     11 Leaves singly serrate or entire (rarely, as in Prunus americana, irregularly and slightly doubly serrate), not lobed basally.
(c) Ward, Scott G
                       12 Gynoecium of separate carpels; fruit an aggregate of follicles; [tribe Spiraeeae]
                          13 Ovary 5-angled in ×-section; fruit a 5-angled capsule; leaves obovate, obviously broadest towards the tip; [tribe Osmaronieae]
(c) Bradley, Keith
(c) Bradley, Keith
                          13 Ovary circular in ×-section; fruit a fleshy spherical drupe; leaves generally broadest near or below the middle; [tribe Amygdaleae]
(c) Weakley, Alan
                     11 Leaves doubly serrate, also often lobed towards the base.
(c) Weakley, Alan
                            14 Corolla yellow; stems arching, green; fruit an aggregate of drupe-like achenes (dry and indehiscent); [tribe Kerrieae]
                            14 Corolla white to pink or rose; stems not both arching and green; fruit various (see below).
(c) Ware, Richard & Teresa - CC-BY-NC, permission granted to NCBG
(c) Ward, Scott G
(c) Ware, Richard & Teresa - CC-BY-NC, permission granted to NCBG
                              15 Inflorescence a dense, umbel-like corymb; leaf apices rounded to acute; fruit an aggregate of 5 follicles; [tribe Neillieae]
                                16 Fruit a single follicle; [exotic, planted, and rarely naturalized, as in e. VA]; [tribe Neillieae]
                                16 Fruit an aggregate of 2-4 drupe-like achenes; [rare native of calcareous habitats in sc. TN, nw. GA, n. AL, and disjunct westward in AR and MO]; [tribe Kerrieae]
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Key to Rosaceae, Key D: Shrubs and trees with compound leaves

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(c) Cressler, Alan M.
1 Leaflets < 5 mm wide, entire; densely-branched shrub to 1 m tall; flowers yellow; [tribe Potentilleae]
1 Leaflets > 10 mm wide, serrate or crenate; shrubs, trees, or woody vines (see below); flowers white, pink, or purplish (rarely yellow in Rosa).
  2 Leaves 1-pinnately compound, generally with > 11 leaflets; inflorescence a terminal panicle or corymb with numerous (> 100) flowers, the petals white and < 4 mm long; fruit a pome or follicle; upright tree or shrub with unarmed stems.
(c) Marcum, Paul
    3 Inflorescence a panicle; fruit a follicle; shrub, to 2 m tall; [tribe Sorbarieae]
(c) Danielson, Erik
(c) Bradley, Keith
    3 Inflorescence a corymb; fruit a pome; tree, generally > 2 m tall; [tribe Pyreae]
  2 Leaves palmately or 1-pinnately compound, generally with < 11 leaflets; inflorescences axillary or terminal panicles or corymbs with few (<15) flowers, the petals white, pink, or purplish (rarely yellow) and > 6 mm long; fruit a hip or aggregate of drupelets; arching or upright shrubs or climbing or sprawling woody vines, the stems usually armed with prickles.
(c) Imbeau, Louis - CC-BY
(c) Radford, Ahles and Bell
(c) Hacker, Patrick - CC-BY
      4 Fruit a hip, developing from a globose to urceolate hypanthium, enclosing the ovaries and achenes, except for the apical orifice; leaflets usually acute to obtuse at the apex; leaflet margins crenulate or serrulate; [tribe Roseae]
(c) Jaxon - CC-BY-NC, permission granted to NCBG
(c) Fleming, Gary P.
(c) Bradley, Keith
      4 Fruit an aggregate of drupelets, developing from a flattish or hemispheric hypanthium, with the ovaries and drupelets exposed; leaflets usually acuminate at the apex; leaflet margins serrate or doubly serrate; [tribe Rubeae]