Flora of the Southeastern United States
2022 Edition

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Key to Parthenocissus

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1 Leaves 3-lobed to 3-foliolate, no leaves 5-foliolate; trailing juvenile plants with 3-foliolate leaves towards the base and 1-foliolate leaves towards the tip; [introduced ornamental, rarely escaped]
1 Leaves (3-) 5-7-foliolate, at least some leaves (on a plant with more than 5 nodes) 5-7-foliolate; trailing juvenile plants with 5-7-foliolate leaves towards the base and 3-foliolate (or rarely one or a few 1-foliolate leaves) towards the tip; [native].
..2 Larger leaves 7-foliolate; leaflets thick and fleshy in texture, 3-5 cm long; leaflets > 1.8× as long as wide; [of c. and barely the western edge of e. TX]
..2 Larger leaves 5-foliolate; leaflets herbaceous in texture, 4-12 cm long; leaflets < 1.5× as long as wide; [collectively widespread in our area]
....3 Inflorescence with a well-developed (zigzag) central axis, the dichotomous branches very unequal, the inflorescence therefore paniculiform; tendrils with mostly 3-8 branches, most or all branches terminating with adhesive disks (though young shoots may not have the disks yet formed); leaves usually dull above; leaflets sessile, subsessile, or short-petiolulate (usually < 5 mm long); leaflet margins toothed primarily past the widest point, with few and obscure teeth below that point; [widespread in our area]
....3 Inflorescence without a well-developed central axis, the dichotomous branches relatively equal, the inflorescence therefore corymbiform, as wide or wider than long, with 2-3 main branches; tendrils with mostly 3-5 branches, usually none terminating in adhesive disks (though sometimes swollen at the tip); leaves usually glossy above; leaflets borne on long petiolules, often > 10 mm long; leaflet margins coarsely and jaggedly toothed, the teeth usually prominent in the lower half of each leaflet as well as the upper half; [from e. VA and n. WV northward]