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Fabaceae
See list of 55 genera in this familyReference: Isely (1998).
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1a. Leaf blades simple or reduced to a tendril
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2a. Plants armed by means of reduced, spine-tipped phyllodes; legume mostly enclosed in the persistent calyx
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2b. Vegetative portions of plants unarmed; fruit visible most of its length
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3a. Leaf blade reduced to a tendril; flowers solitary (rarely paired) on slender peduncles (in part)
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3b. Leaf blade broad, not tendril-like; flowers arranged in racemes, fascicles, or umbels
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4a. Leaf blade obovate to narrow-obovate, gradually tapering toward the base into the petiole; legume spirally coiled, armed with thin prickles along the outer surface of the spiral
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4b. Leaf blades linear to lanceolate or elliptic, or elliptic to broad-cordate-ovate, either sessile or rather abruptly transitioning from blade to petiole; fruit not spirally coiled (but curved in Coronilla), without prickles
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5a. Plants herbaceous, annual; fruits plump, ± terete in cross-section
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6a. Stipules adnate to the stem forming conspicuous, decurrent wings [Fig. 634]; corolla 9–11 mm long; fruit a legume, very inflated, straight
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6b. Stipules not adnate to the stem (though connate to each other), not forming decurrent wings; corolla 4–8 mm long; fruit a schizocarp, not bladder-like, curved (in part)
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5b. Plants woody, perennial; legumes compressed
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7a. Leaves without petioles, the blades elliptic to lanceolate; flowers serotinous, with a yellow corolla; legume 1.5–3 cm long
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7b. Leaves with petioles, the blades broad-cordate-ovate; flowers precocious, with a deep pink corolla; legume 6–10 cm long
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1b. Leaf blades compound (sometimes the upper 1-foliate in Cytisus)
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9a. Plants definitely woody
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10a. Leaf blade surface with minute, glandular dots; corolla with 1 petal––the banner petal
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10b. Leaf blade surface without glandular dots; corolla with 5 petals (note: the 2 lower petals fused to form the keel and thus the corolla appearing as 4 petals in Caragana, Cladrastis, Colutea, Robinia, and Wisteria)
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11a. Plants lianas; petals blue, blue-purple, or purple (rarely white or pink)
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11b. Plants trees or shrubs; petals largely or wholly white, yellow, or pink to red-purple
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12a. Leaves bipinnately compound with strongly asymmetrical leafules, the midvein of the leafule at or near one margin [Fig. 630]; each flower with numerous stamens
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12b. Leaves pinnately or bipinnately compound, when bipinnately compound with ± symmetrical leafules, the midvein of the leafules aligned along the center of the blade; each flower with 5–10 stamens
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13a. Perianth actinomorphic; stamens distinct, with versatile anthers; legume (6–) 8–40 (–50) cm long; leaves pinnately or bipinnately compound
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14a. Leaves all bipinnate, with petioles 20–40 mm long and entire leafules; hypanthium 6–10 mm long; legume (6–) 8–15 (–25) cm long
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14b. Leaves pinnate on spurs and bipinnate on new, terminal growth, with petioles up to 20 mm and obscurely crenate leaflets or leafules (depending on division of blade); hypanthium 3–5 mm long; legume 15–40 (–50) cm long
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13b. Perianth zygomorphic; stamens diadelphous (distinct in Cladrastis), with basifixed anthers; legume 4–10 cm long; leaves pinnately compound
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15a. Leaflets alternately arranged along the rachis, (4–) 6–15 (–20) cm long
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15b. Leaflets oppositely or suboppositely arranged along the rachis [Fig. 632], 1–6 cm long
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16a. Leaves paripinnate [Fig. 632]; inflorescence a fascicle with 2–4 flowers; winter bud not concealed by petiole base
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16b. Leaves imparipinnate [Fig. 649]; inflorescence a raceme with 2–20 (or more) flowers; winter bud concealed within or surrounded by base of petiole
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17a. Corolla yellow; legume very inflated; calyx with subequal lobes
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17b. Corolla white or pink to pink-purple; legume flat; calyx ± bilabiate
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9b. Plants herbaceous
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18a. Some or all of the filaments distally widened; inflorescence a dense umbel (a solitary, peduncled flower in Lotus unifoliatus) [Fig. 650]
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19a. Inflorescence subtended by palmately lobed bracts; terminal leaflet usually considerably longer than the adjacent lateral leaflets; fruit enclosed in the calyx
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19b. Inflorescence without palmately lobed bracts; terminal leaflet of ± similar length to the adjacent lateral leaflets; fruit much longer than the calyx and visible most or all of its length
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20a. Corolla yellow (later becoming orange marked with red); leaf blades appearing to have 5 leaflets, the basal 2, which are actually stipules, separated from the apical 3; fruit a legume
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20b. Corolla pink and/or white; leaf blades with 11–25 evenly spaced leaflets; fruit a schizocarp
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21a. Schizocarp terete or angled, not flat, 20–50 mm long, weakly constricted between the seeds; calyx zygomorphic; corolla 10–15 mm long, usually pink and white; plants perennial
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21b. Schizocarp ± flat, 10–25 mm long, strongly constricted between the seeds; calyx nearly actinomorphic; corolla 6–8 mm long, usually pink with purple lines; plants annual
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18b. All of the filaments slender, not dilated near the apex; inflorescence a raceme, spike, or a solitary flower
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22a. Leaves paripinnate (i.e., the terminal leaflet absent or modified into a tendril) [Figs. 640,641,656]
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23a. Leaves with 30–60 leaflets (the upper leaves with fewer leaflets); fruit 10–20 cm long, transversely septate
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23b. Leaves with 2–22 leaflets; fruit 0.6–9 cm long (5–20 (–30) cm in Vicia faba, a rare escape), not transversely septate
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24a. Androecium monadelphous; anthers dimorphic—alternately obloid and globose; fruit developing underground, indehiscent, with a fibrous-reticulate pericarp; tendrils lacking
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24b. Androecium diadelphous; anthers monomorphic; fruit developing above ground, dehiscent, the pericarp not fibrous-reticulate; tendrils present (absent in Vicia faba)
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25a. Stipules foliaceous, ± as large as or larger than the leaflets; style longitudinally folded
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25b. Stipules small to prominent, usually smaller than the leaflets [Figs. 640,641]; style not longitudinally folded
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26a. Calyx lobes all 2–4 times as long as the basal, connate portion; legume 10–14 ×5–9 mm, with 1 or 2 seeds
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26b. Calyx lobes (or at least some of them) less than 2 times as long as the basal, connate portion; legume 6–300 mm long, when less than 14 mm long only 3–5 mm wide, with 2–15 or more seeds
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27a. Styles slightly widened and flattened in the apical portion, pubescent along the distal, inner surface; wing petals essentially free from the keel petals; leaves with 2–12 leaflets 15–80 mm long; stems winged in some species (in part)
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27b. Styles filiform-terete, pubescent in a ring around the apex, or on the outer surface, or glabrous; wing petals cohering to the keel petals; leaves with 4–22 leaflets 5–35 mm long (40–100 mm in V. faba); stems angled or ridged, but not winged
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28a. Sepals distinct; stamens distinct or shortly connate near base [Fig. 633]; uppermost petal internal to the adjacent lateral petals in bud; petioles (or rachises in 1 species) with 1 or more prominent glands on the adaxial surface
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29a. Stipules longitudinally striate; pedicels subtended by two bracteoles; stamens with well-formed anthers; legume elastically dehiscent, not transversely septate
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29b. Stipules without longitudinal striae; pedicels ebracteate; upper 3 stamens without well-formed anthers; legume indehiscent or inertly dehiscent, with transverse septa
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28b. Sepals connate; stamens monadelphous or diadelphous; uppermost petal external to the adjacent lateral petals in bud; petiole lacking prominent, adaxial glands
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30a. Leaf blades with minute glandular scales or dots (at least on one surface)
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31a. Wing petals tiny, much shorter than keel; legume 1-seeded, woody, prominently rugose with raised veins, the lower margin toothed
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31b. Wing petals larger, at least ½ as long as the keel; legume with 1 or more seeds, membranaceous to coriaceous, not prominently rugose, lacking teeth on the lower margin (but covered in uncinate prickles in Glycyrrhiza)
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32a. Inflorescence a raceme with pale yellow flowers; wing and keel petals attached to the receptacle; stamens concealed in intact flowers; fruit 12–15 mm long, armed with uncinate prickles
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32b. Inflorescence a dense, obloid to cylindrical spike with white to blue-purple flowers; wing and keel petals attached laterally or apically to the basal, connate portion of the stamens; stamens shortly exserted and visible; fruit 2.5–3 mm long, unarmed
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30b. Leaf blades without glandular scales or dots
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33a. Leaves with 5–7 leaflets; corolla purple-brown; climbing or trailing vines with tuberous rhizomes
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33b. Leaves with 7–31 leaflets; corolla purple or white; upright to decumbent herbs, but not trailing, without tuberous rhizomes
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34a. Leaflets coarsely serrate near apex; fruit stipitate-glandular
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34b. Leaflets entire; fruit not stipitate-glandular
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35a. Racemes terminal or opposite the leaves; corolla distinctly bicolored—the banner petal yellow to ochroleucous, the wing and keel petals pink to pale purple; style barbellate
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35b. Racemes axillary; corolla not bicolored, purple with varying degress of pink, red, or blue tinting, or white to ochroleucous; style not barbellate
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36a. Stipules semisagittate to hastate (i.e., with 1 or 2 basal lobes); fruit 30–50 mm long, longitudinally striate
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36b. Stipules without basal lobes; fruit 5–30 (–35) mm long, without longitudinal striae
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37a. Fruit a schizocarp with 2–5 mericarps; raceme secund in flower
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37b. Fruit a legume; raceme spirally arranged in flower
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38a. Keel obtusely to acutely pointed; plants with short, but evident, stems; leaflets 1.3–3.5 times as long as wide (4–5 times as long as wide in A. eucosmus)
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38b. Keel abruptly short-pointed; plants acaulescent or nearly so; leaflets 3.5–6 times as long as wide
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39a. Plants definitely woody
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40a. Branchlets 4- or 5-angled; inflorescence composed of solitary or paired flowers in the axils of the upper leaves; legume pubescent only on the margin
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40b. Branchlets terete; inflorescence a pendulous raceme 15–25 cm long; legume pubescent over the surface
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39b. Plants herbaceous or sub-woody
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41a. Leaves palmately compound with 7–17 leaflets; androecium with monadelphous filaments and dimorphic anthers—one type of anther subglobose and versatile, the other linear and basifixed
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41b. Leaves pinnately or palmately compound with 3 or fewer leaflets; androecium with distinct or diadelphous filaments (monadelphous in Hylodesmum and submonadelphous in Pueraria) and monomorphic anthers
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42a. Leaflets toothed, at least minutely in the apical portion [Fig. 653]
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43a. Stipules entire, 1-nerved, the distinct portion 8 or more times as long as wide; inflorescence (1–) 4–20 cm tall during anthesis, usually 4–15 times as tall as wide [Fig. 647]
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43b. Stipules entire or toothed, 2- or 3-nerved, the distinct portion commonly less than 8 times as long as wide; inflorescence 0.3–10 cm tall, rarely exceeding 3 times as tall as wide
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44a. Leaflets all with petiolules of ± similar length (in part)
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44b. Terminal leaflet on a petiolule distinctly longer than the petiolules of the lateral leaflets [Fig. 653]
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45a. Calyx actinomorphic; fruit curved to coiled as many as 7 times (rarely straight in M. falcata) [Fig. 645]
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45b. Calyx zygomorphic; fruit straight or slightly curved
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46a. Corolla marcescent; 5 or all of the filaments dilated near the apex; legume shorter than 10 mm, included or barely exserted from the persistent calyx (in part)
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46b. Corolla deciduous; all the filaments slender at the apex; legume 10–16 mm long, long-exserted from the persistent calyx
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42b. Leaflets entire or sometimes with 1–3 lobes in Pueraria and Strophostyles
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47a. Leaves paripinnate, the terminal leaflet modified into a tendril (in part)
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47b. Leaves imparipinnate, the terminal leaflet present
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48a. Terminal leaflet much larger than the orbicular to reniform lateral leaflets (i.e., usually more than 2.5 times as long); fruit a schizocarp, prominently curved, without uncinate hairs (in part)
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48b. Terminal leaflet not or only somewhat larger than the lateral leaflets (i.e., usually less than 1.5 times as long, sometimes much larger in a few species of Desmodium and Hylodesmum, but those species with narrower lateral leaflets); fruit a schizocarp with uncinate hairs or a legume, ± straight
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49a. Stamens distinct; corolla yellow (white to yellow-white or light-purple to blue-purple in some Baptisia)
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50a. Petioles 10–25 mm long; legume strongly compressed, 40–80 mm long; ovary sessile or borne on a stipe up to 3 mm long in fruit
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50b. Petioles 2–10 mm long, becoming nearly obsolete on upper leaves; legume turgid or inflated, 7–50 (–60) mm long; ovary stipitate, the stipe 5–15 mm long in fruit
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49b. Stamens diadelphous, 9 stamens connate into a group with 1 separate stamen (monadelphous in Hylodesmum and submonadelphous in Pueraria); corolla pink to purple, white, or yellow-white
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51a. Leaflets without stipels [Fig. 639]; ovary with 1 ovule, maturing as a 1-seeded, indehiscent fruit
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52a. Petiolule of terminal leaflet clearly longer than the petiolules of the lateral leaflets (i.e., the leaves pinnately compound); stipules subulate or setaceous, not striate; calyx lobes acuminate; plants perennial
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52b. Petiolule of terminal leaflet ± the same length as the petiolules of the lateral leaflets (i.e., the leaves palmately compound); stipules narrow-ovate, striate [Fig. 639]; calyx lobes blunt; plants annual
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51b. Leaflets usually with stipels [Fig. 638]; ovary with 2 or more ovules, maturing as a fruit with 2 or more seeds ( Amphicarpaea also producing more or less apetalous flowers from near the base of the plant with 1 ovule)
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53a. Fruit a schizocarp; plants erect or ascending (prostrate in Desmodium rotundifolium)
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54a. Stamens monadelphous; distinct portion of the calyx (i.e., the lobes) less than 50% as long as the connate portion (i.e., the tube); lower margin of schizocarp deeply incised such that the sinuses extend completely to the upper suture; schizocarp borne on a stipe exceeding the length of the persistent stamens, glabrous on the upper suture
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54b. Stamens diadelphous; distinct portion of the calyx more than 50% as long as the connate portion; lower margin of schizocarp moderately incised such that the sinuses do not extend the entire distance to the upper suture; schizocarp borne on a stipe that is shorter than the persistent stamens, uncinate-pubescent on the upper suture
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53b. Fruit a legume; plants trailing, twining, or climbing (i.e., vines; with upright stems in Glycine and sometimes in Phaseolus vulgaris)
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55a. Bracts of pedicels obtuse to rounded at the apex; flowers without subtending bracteoles; plants with dimorphic flowers—petaliferous flowers with 10 diadelphous stamens and maturing as a 3- or 4-seeded aerial fruit, and more or less apetalous flowers with fewer than 10 distinct stamens and maturing as a 1-seeded, often subterranean, fruit
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55b. Bracts of pedicels acute at the apex; flowers with closely subtending bracteoles that overlap the calyx (caution: the bracteoles caducous in Pueraria); plants with monomorphic, petaliferous flowers
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56a. Corollas 5–7 mm long; plants upright; inflorescence a raceme
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56b. Corollas 8–25 mm long (as short as 3.6 mm in the very rare introduction Strophostyles leiosperma); plants vining (sometimes upright in Phaseolus vulgaris); inflorescence a pseudoraceme (i.e., with 2 or more flowers produced from some nodes)
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57a. Keel petal relatively straight; style glabrous; leaflets ovate to suborbicular, 0.8–1.2 times as long as wide
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57b. Keel petal conspicuously arched or coiled inward; style pubescent; leaflets lanceolate or narrow-elliptic to ovate or rhombic, 1–8 (–10) times as long as wide
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58a. Plants pubescent with hairs that are not hooked at the tip and are visible at low magnification; some leaflets often with a lateral lobe on one or both sides; calyx with 4 lobes due to fusion of 2 lobes; keel petals arched inward [Fig. 651]; inflorescence capitate, spike-like
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58b. Plants with minute, uncinate hairs (note: view at 20 × or higher magnification); leaflets unlobed; calyx with 5 lobes; keel petals coiled inward [Fig. 648]; inflorescence elongate, raceme-like
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Each photo represents one genus in this family.