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Key to Astragalus

Fabaceae

Astragalus

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1 Hairs of the stems and leaves malpighian (with 2 arms) (use 10× or greater magnification).
  2 Plants erect or ascending, the stems 3.5-16 dm long; legume 4.0-5.2 mm in diameter; legume (9-) 10-15 mm long; stipules connate, 3-18 mm long; [widespread in our region]; [section Uliginosi]
  2 Plants prostrate or decumbent, the stems to 1.7 dm long; legume (4-) 5-10 mm in diameter; legume 12-37 mm long; stipules not connate (or rarely so towards the base of the plant only), (2-) 3-9 mm long; [OK and TX westwards].
    3 Calyx tube 3.2-4.5 mm long; keel petal 4.2-9.8 mm long; corollas whitish, ochroleucous or pink to lavender (usually only lightly so); [section Lotiflori]
    3 Calyx tube 6.3-9.3 mm long; keel petal (11.5-) 12.8-17.3 (-18.5) mm long; corollas usually deeply pink or lavender (rarely to whitish); [section Argophylli]
1 Hairs of the stems and leaves basifixed, simple.
      4 Legume pilose with hairs > 1 mm long; stems conspicuously pubescent, the hairs spreading; plants decumbent, spreading, or ascending, the stems 0.5-4 dm long.
        5 Corolla 14-19 mm long; leaflets 17-29; legume bilocular; calyx lobes shorter than the calyx tube; [of calcareous habitats of the Interior]
        5 Corolla 8-12 mm long; leaflets (5-) 7-15; legume unilocular; calyx lobes equaling or longer than the calyx tube [of dry sandy habitats from SC south]
      4 Legume glabrous or with pubescence < 1 mm long; stems glabrous or pubescent, the hairs appressed, plants erect or decumbent with stems 1-15 dm long.
          6 Plants perennial, with rhizomes or woody taproot.
             7 Plants erect, stems 1-15 dm tall; legume dry and straight to moderately curved (A. chinensis legumes fleshy and pendulous).
               8 Plants slender, 1-7(-11) dm tall; racemes loosely flowered and elongating in fruit; legumes boat shaped and fleshy, 4-9 mm long; [c. OK in our region]; [section Scytocarpi]
               8 Plants stout or if slender, e of Mississippi River, (3-) 4-15 dm tall; racemes more densely flowered; legumes various but not boat shaped and > 9 mm long.
                 9 Flowers bright yellow; legumes fleshy and pendulous, transversely rugose in age; [Payne Co., OK in our region]; [section Nuculiella]
                 9 Flowers creamy white, ochroleucous, or variously tinged with pink or purple; legumes not fleshy or pendulous, smooth in age; [e. of Mississippi River or more widespread in c. OK].
                   10 Legume with stipe 3-5 mm long, sharply triangular; [se. and c. OK in our region]; [section Bisulcati]
                   10 Legume sessile or with short stipe to 1 mm long, rounded; [NC s. to e. GA or VA north].
                     11 Leaves with 21-31 coriaceous to somewhat fleshy leaflets, many of the leaflets alternate or subopposite; flowers pink-purple or whitish and tinged with lilac; legumes 2-3 cm long, 4-6 mm in diameter; [of dry sandy habitats from NC south]
                     11 Leaves with 11-23 thin-textured leaflets, all of the leaflets usually opposite; flowers creamy white; legumes 1.5-3 cm long, 8-18 mm in diameter; [of rocky calcareous habitats from VA north]
             7 Plants decumbent or ascending, stems 1-5 dm long; legume either dry and strongly curved (about 90 degrees), plump-ellipsoid, or globose and initially fleshy.
                       12 Legume lanceolate, 1.2-2.5 cm long, 4-7 mm wide, strongly curved; corolla (7-) 8-15 mm long.
                          13 Leaflets mostly 1-2× as long as wide, typically noticeably notched at the tip; mature legume reticulately textured; corolla (7-) 8-11 mm long; [of dry sandy sites in FL and possibly adjacent GA and s. MS]
                          13 Leaflets mostly 2-3.5× as long as wide, truncate or shallowly notched at the tip; mature legume lacking a reticulately textured surface; corolla 9-15 mm long; [either of shaley habitats from w. VA northward or of woodlands and prairies from MS westward].
                            14 Corollas greenish-white to cream or yellowish cream, 12–18 mm long; mature legumes 5–8 mm wide; sandy substrates; [rare]
                            14 Corollas variously pink to purple, lilac or whitish, 4–15.5 mm long; mature legumes 1.8–7 mm wide; rocky, gravelly, or shaly substrates.
                              15 Keel 7-9.5 mm long; legume usually 3-4× as long as wide, often curved 90°, grooved along sutures on both sides
                              15 Keel 6-7 mm long; legume usually 2.5-3.5x as long as wide, nearly straight or curved < 90°, grooved only along one suture
                                16 Plants conspicuously villous white-tomentose; legume plump-ellipsoid, not fleshy, 4-13 mm wide; [c. OK in our region]
                                16 Plants glabrous or inconspicuously pubescent; legume globose or plumply oblong-ellipsoid, initially fleshy, 10-27 mm wide; [more widespread or east of the Mississippi River].
                                  17 Ovaries and legumes glabrous; plants glabrate or strigulose; mature legumes 11–27 mm wide; [c. TX n. and e. to IL and c. LA].
                                    18 Pubescence of calyx densely and softly white-tomentose, < 1 mm long; flowers yellowish-white; [ne. TX n. and e. to sw. IL]
                                    18 Pubescence of calyx with long black or mix of white and black hairs to 1.5 mm long or thinly pilose; flowers purple, pink-purple, or lilac; [sw. AR, OK, and c. TX or c. TN].
                                       19 Pubescence of calyx with long black or mix of white and black hairs to 1.5 mm long; legume 12-27 mm wide; [c. TX and OK].
          6 Plants annual, with slender taproot.
                                           21 Plants prostrate; calyces with mixed black and white strigose pubescence; legumes coiled into the shape of a horseshoe or fishhook; [only known as rare waifs on chrome ore piles in MD]
                                           21 Plants erect or ascending, rarely prostrate (A.emoryanus); calyces glabrous or with pale pubescence; legumes various but not coiled; [widespread, mostly w. of Mississippi River].
                                             22 Plants prostrate and mat-forming; legumes dehiscent after detaching from plant; [only in Lower Rio Grande Valley in our region]
                                             22 Plants mostly erect or ascending; legumes dehiscent while still attached to plants; [more widespread].
                                                    25 Legumes peltate, 3.5-7 mm long and 4.5-7.5(-9) mm wide; peduncles strigose; keel shorter than the wings; corollas 6-8(-9) mm long; [uncommon in s. TX]
                                                    25 Legumes ovate-lunate in side view, ovate-deltoid from above, 5.5-9 mm long and 2.5-5.5 mm wide; peduncles with wide-spreading hairs; keel longer than the wings (= exserted); corollas 4-7 mm long; [very rare in c. or s. TX]
                                                      26 Corollas (12-) 13-18 mm long, showy; wings wholly white in apical 2/3; seeds 8-12; style pubescent; mature legumes 3.5-6.5 mm wide, stipitate, the stipes 1-3 mm long
                                                      26 Corollas 4-13 mm long; wings colored to apex along lower edge; seeds 10-26; style glabrous; mature legumes 1.8-3.5 mm wide, sessile or nearly so, the stipes < 1 mm long.
                                                        27 Inflorescences racemose with 4-20 flowers (usually more than 10), axis elongating to 1-3 cm in fruit; keel tip obtuse; banners 8-13 mm long; [rare in c. TX]
                                                        27 Inflorescences subumbellate with 1-10 flowers, axis scarcely elongating to 1 cm in fruit; keel tip acute; banners 3.7-13 mm long.
                                                          28 Mature legumes 20-37 mm long, straight or gently and evenly curved for their whole length, glabrous; seeds 20-26; banners 8.3-13 mm long; primarily on sandy soils; [sw. AR, w. LA, s. OK, and e. TX]
                                                          28 Mature legumes 12-26 mm long, usually curved near base, otherwise straight or nearly so, glabrous or with pubescence; seeds 10-18; banners 3.7-7.3 mm long; primarily on calcareous substrates; [c. OK and c. TX]
                                                            29 Calyx teeth 1.5-2.5 times as long as calyx tube; mature legumes densely pilose-hairy, 7-13 mm long, straight or nearly so, erect; calyces over half as long as corollas to nearly as long as corollas; seeds 5-9; [rare in c. TX]
                                                            29 Calyx teeth about equal in length to calyx tube; mature legumes glabrous or sparsely hairy, 12-26 mm long, curved near base or straight, spreading, ascending, or deflexed, not erect; calyces half as long as corollas or less; seeds 10-18; [more common].
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Key to Astragalus nuttallianus complex: Key to Astragalus nuttallianus complex

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1 Leaflets of all leaves notched or truncate-emarginate.
  2 Inflorescences racemose with 4-20 flowers (usually more than 10 and showy), the keel-tip obtusely rounded; raceme axis elongating and usually 1-3 cm long in fruit; [rare in c. TX]
  2 Inflorescences subumbellate with 1-7 (-12) flowers; the keel-tip triangular-acute or sharply deltoid; raceme axis not elongating or scarcely so, < 1 cm long in fruit.
    3 Mature legumes 20-37 mm long, straight or gently and evenly curved for their whole length, glabrous; seeds 20-26; banners 8.3-13 mm long; primarily on sandy soils; [sw. AR, w. LA, s. OK, and e. TX]
    3 Mature legumes 12-26 mm long, usually curved near base, otherwise straight or nearly so, glabrous or with pubescence; seeds 10-18; banners 3.7-7.3 mm long; on calcareous substrates; [widespread mostly w. of Mississippi River or s. TX].
      4 Legumes loosely strigulose or minutely hirsute; leaflets minutely hirsute; [s. TX and adjacent Mexico]
1 Leaflets not all notched or truncate-emarginate, elliptic or ovate and obtuse to subacute in at least some upper or often all leaves.
        5 Inflorescences racemose with 4-20 flowers (usually more than 10), banners 8.5-13 mm long, keel obtusely rounded at tip; racemes elongating, the axis 1-3 cm long in fruit; legumes commonly glabrous; [rare in c. TX]
        5 Inflorescences subumbellate with 1-10 flowers, banners 4-9 (-9.5) mm long; keel triangular or narrowly deltoid at tip, acute or subacute; racemes not or scarcely elongating, the axis 0.8 (-1.2) cm or less long in fruit; legumes glabrous or with pubescence; [more common in OK and TX].
          6 Flowers with banners 7-9 (-9.5) mm long; racemes mostly with 4-10 flowers; legumes consistently glabrous; leaves lightly pubescent on upper surfaces; [endemic to e. half of TX]
          6 Flowers with banners 4-7 mm long; racemes mostly with 1-5 (-6) flowers; legumes glabrous or with pubescence; leaves usually densely pubescent on both surfaces.
             7 Legumes glabrous or if pubescent the hairs shorter, appressed, 0.5 mm long or less; leaflets commonly 7-11; [OK and TX, mostly westward]
             7 Legumes hirsutulous, the hairs 0.5-1 mm long; leaflets commonly 11-13; [OK and TX, mostly eastward]