1 Leaves pinnately compound, with 3 (-5) leaflets; leaflet margins serrate; trees; [subfamily Antidesmatoideae; tribe Bischofieae]

1 Leaves simple; leaf margins entire; shrubs, trees, and herbs; [subfamily Phyllanthoideae].

  2 Herbs.

    3 Plant with “normal” arrangement of branches and leaves (leaves uniformly distributed on the stem and branches, alternate and either distichous or spirally arranged, the ultimate branches not deciduous, flowers produced on ultimate and penultimate orders of branches).

      4 Leaves arranged spirally; staminate sepals 0.7-2.5 mm long; stipules not auriculate

      4 Leaves arranged distichously; staminate sepals 0.5-0.7 mm long; stipules typically auriculate

    3 Plant with “phyllanthoid” arrangement of branches, leaves, and flowers (leaves lacking on the main stem, the penultimate order of branches with scales arranged spirally, the ultimate (final) order of branches deciduous, bearing normal leaves alternately and distichously, flowers produced only on the ultimate, deciduous branches), the ultimate branches and their distichous small leaves resembling the rachis and leaflets of a once-pinnate compound leaf.

        5 Fruiting pedicels 0.5 mm long; seeds with 12-15 transverse ridges and sometimes 1-3 pits; male flowers borne toward the tip of the branchlets, female flowers toward the base

  2 Shrubs or trees.

          6 Ultimate branchlets flattened into cladodes; leaves on ultimate branchlets scale-like, caducous; flowers borne in axils of scales, in notches of the cladodes

          6 Ultimate branchlets terete, "normal"; leaves on ultimate branchlets leaf-like, flattened , with a blade; flowers borne in axils of leaves.

             7 Plant with “normal” arrangement of branches and leaves (leaves uniformly distributed on the stem and branches, alternate and either distichous or spirally arranged, the ultimate branches not deciduous, flowers produced on ultimate and penultimate orders of branches); staminate flowers lacking pistillodes.

               8 Leaves deciduous; fruits berries, 3-5 mm in diameter; petals absent; nectary in staminate flowers of of 5 glands

               8 Leaves evergreen; fruits capsules, 3.6-7 (-9) mm in diameter; petals present; nectary in staminate flowers an annular disc.

                 9 Staminate flowers 6-25, sessile to subsessile in a glomerule; pistillate petals 1-2 mm long; shrub or tree to 4 (-8) m tall; [FL keys]

                 9 Staminate flowers 1-2 (-4), pedicellate in a fascicle; shrub to 1 m tall; pistillate petals 0.4-0.8 mm long; [inland provinces, AL, TN, MO, AR, OK, TX]

             7 Plant with “phyllanthoid” arrangement of branches, leaves, and flowers (leaves lacking on the main stem, the penultimate order of branches with scales arranged spirally, the ultimate (final) order of branches deciduous, bearing normal leaves alternately and distichously, flowers produced either only on the ultimate branches [Breynia disticha, Glochidion puber], or on short shoots on old wood [Cicca acida]), the ultimate branches and their distichous small leaves resembling the rachis and leaflets of a once-pinnate compound leaf; staminate flowers with pistillodes

                   10 Fruits greenish white to yellow-orange drupes, (12-) 15-20 (-25) mm in diameter; inflorescences borne on short shoots on old growth

                   10 Fruits capsules, 4-15 mm in diameter; inflorescences borne in axils of leaves on the ultimate branches.

                     11 Leaf blades ca. 1.5× as long as wide, broadly rounded at the apex; pistils 3-carpellate, each of the 3 styles 2-branched

                     11 Leaf blades3× as long as wide, acute to acuminate at the apex; pistils 5-10-carpellate, each of the 5-10 styles unbranched

1 Plant a floating aquatic; [subgenus Phyllanthus; section Loxopodium]

1 Plant a rooted terrestrial.

  2 Plants woody, shrubs or trees, 10-100 dm tall.

    3 Ultimate branchlets terete; leaves on ultimate branchlets well-developed, falling with the branchlet; fruits drupes; tree to 10 m tall

    3 Ultimate branchlets flattened into cladodes; leaves on ultimate branchlets scale-like, caducous; fruits capsules; shrub to 3 m tall; [subgenus Xylophylla; section Xylophylla]

  2 Plants perennial or annual herbs, or woody (suffrutescent) at the base only, 0.5-5 dm tall.

      4 Plant with “normal” arrangement of branches and leaves (leaves uniformly distributed on the stem and branches, alternate and either distichous or spirally arranged, the ultimate branches not deciduous, flowers produced on ultimate and penultimate orders of branches).

        5 Leaves arranged spirally; staminate sepals 0.7-2.5 mm long; stipules not auriculate; [section Paraphyllanthus].

        5 Leaves arranged distichously; staminate sepals 0.5-0.7 mm long; stipules typically auriculate; [subgenus Phyllanthus; section Loxopodium].

          6 Stems flattened and winged; filaments connate; seeds 1.3-1.5 mm long; [of e. LA westward]

          6 Stems terete; filaments free; seeds 0.7-1.1 mm long; [widespread in our region].

             7 Pistillate sepals 0.2-0.3 mm wide; leaf venation clearly visible on the lower surface; stems glabrous; cymules with 1 staminate and (1-) 2-3 (-5) pistillate flowers; pistillate nectary cupular, unlobed, enclosing the ovary 1/3-1/2 of its length; [widespread in our region]

             7 Pistillate sepals (0.2-) 0.3-0.5 (-0.7) mm wide; leaf venation obscure on the lower surface; stems scabridulous; cymules with 1-2 staminate and 1-2 pistillate flowers; pistillate nectary annular, unlobed or 6-lobed, enclosing the ovary only basally; [s. FL]

      4 Plant with “phyllanthoid” arrangement of branches, leaves, and flowers (leaves lacking on the main stem, the penultimate order of branches with scales arranged spirally, the ultimate order of branches deciduous, bearing normal leaves alternately and distichously, flowers produced only on the ultimate, deciduous branches), the ultimate branches and their distichous small leaves resembling the rachis and leaflets of a once-pinnate compound leaf.

               8 Stamens 5, filaments free; fruiting pedicels capillary, 3-7 mm long, flexuous and pendent in fruit; seeds densely papillose; [subgenus Kirganelia]

               8 Stamens 3, filaments connate into a column 0.1-0.15 mm long; fruiting pedicels thicker and often also shorter, spreading in fruit; seeds variously ribbed or striate.

                 9 Fruiting pedicels 0.5 mm long; seeds with 12-15 transverse ridges and sometimes 1-3 pits; male flowers borne toward the tip of the branchlets, female flowers toward the base; [section Urinaria]

                 9 Fruiting pedicels > 0.5 mm long; seeds either longitudinally ribbed or striate, or verrucose; female flowers borne toward the tip of the branchlets, male flowers toward the base; [section Phyllanthus].

                   10 Pistillate sepals 3-3.5 mm long, pinnately veined; staminate sepals 1.5-3 mm long; seeds verrucose, 1.5-1.8 mm long; capsules 3.5 mm in diameter; pistillate nectary annular, unlobed; [subgenus Phyllanthus; section Phyllanthus]