Astragalus
Creators: name: Castillón, Eduardo Estrada
name: Quintanilla, José Ángel Villarreal
name: Salinas, Alfonso Delgado-
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Fabales
Fabaceae
Astragalus

description: Key to identify the different sections of Astragalus in Mexico.
1. Stipules always free or the lowest semi or almost fully amplexicaule, but never connate ................................................................2
- Stipules, at least at the lowest nodes connate...................................................................................................................................20
2. Plants densely pubescent with short curly trichomes mixed with longer spirally twisted ones, appressed or spreading up to 2 mm long.....................................................................................................................................................................................................3
- Plant variously pubescent, but the trichomes 1.5 mm long or shorter, none spirally twisted ............................................................4
3. Stems prostrate or decumbent, usually shorter than the longest leaves; flowers ascending; pods humistrate with age, soon caducous ..................................................................................................................................................................... sect. Mollissimi
- Stems erect, caulescent, the stems longer than longest leaves; flowers soon deflexed; pod erect, never humistrate, persistent......... ....................................................................................................................................................................................... sect. Gigantei
4. Always annual; ovary (and pod) with 2 ovules only.............................................................................................. sect. Microlobium
- Annual or perennial; ovary (and pod) with 4 or more ovules ............................................................................................................5
5. Flowers red or, if purple, the plants acaulescent ................................................................................................................................6
- Flowers purple, blue, white, lilac, concolorous, or mixtures of these colors, but never completely red; caulescent plants..............7
6. Calyx-tube shallowly campanulate, 2–4.5 mm long; banner 14 mm long or shorter; pubescence always dolabriform sect. Lotiflori
- Calyx-tube cylindric or deeply campanulate, 6–10.5 mm long; banner 16–22 mm long; pubescence simple or dolabriform............ .................................................................................................................................................................................... sect. Argophylli
7. Pod inflated, bladder-like of papyrus texture, stiffly so or papery-membranous, unilocular or bilocular .........................................8
- Pod triquetrous or dorsoventrally flattened, not bladdery inflated, narrow elliptic, linear-oblong, oblong-elliptic, oblique-obovate or subterete in cross section, always bilocular .................................................................................................................................14
8. Flowers very small, banner 5.5–6.5 mm long; pod 4–8 mm long, persistent ................................................................sect. Scalares
- Flowers longer than 7 mm; pod much longer than 8 mm, caducous..................................................................................................9
9. Pod stipitate, the stipe 7–17 mm long ....................................................................................................................... sect. Trichopodi
- Pod sessile to subsessile, stipe (if present), 0.2-0.5 mm long ..........................................................................................................10
10. Pod unilocular...................................................................................................................................................................................11
- Pod bilocular (at least below the apex or beak .................................................................................................................................12
11. Lowest stipules semi or almost fully amplexicaule......................................................................................................sect. Densifolii
11. Stipules all free ...................................................................................................................................................................sect. Inflati
12. Banner 7–9.5 mm long; pod retuse in both extremes even when young, minutely apiculate and bilocular at apex............................ .........................................................................................................................................................................................sect. Diphaci
- Banner 10–16 mm long; pod never retuse in both extremes, the apex ending into a triangular unilocular beak ............................13
13. Pod 12–23 mm long; pedicels persistent; ovules 10–42; calyx campanulate, teeth shorter than the tube...................... sect. Diphysi
- Pod 6–8 mm long; pedicels caducous; ovules 4; calyx urceolate-suboblong to urceolate-globose, the teeth the same size as the tube ................................................................................................................................................................................ sect. Rupertii
14. Peduncles dimorphic, the early ones very short, up to 2.6 cm long, with only 1–2 flowers, the later ones, up to 7-flowered; the banner 5–5.5 mm long; pod pendulous, sessile, subunilocular, 6–10 mm long......................................................sect. Quinqueflori
- Peduncles homomorphic, if flowers are small, the root annual and pod larger, if the pod is small, the flowers more than 7-flowered; pod fully bilocular ............................................................................................................................................................................15
15. Pod declined or deflexed, sessile, or elevated on a stipe-like gynophore, the body very strongly dorsoventrally compressed, peltiform or shield-shaped, as broad as long or not much longer ................................................................................. sect. Scutanei
- Pod ascending, spreading or deflexed, sessile or stipitate, sometimes shortly so, the body mostly lance-oblong, in profile, half ovate, in any case triquetrous or compressed triquetrous, or the body subterete to dorsoventrally flattened, linear-oblong, elliptic, oblong-elliptic, ovate-elliptic to wide-elliptic to wide-oblong, twice to many times longer than wide...........................................16
16. Pod dorsoventrally flattened, somewhat bulged, persistent on the receptacle, the body elliptic, oblong-elliptic to ovate-elliptic, straight, dorsoventrally compressed, one to one and a half longer than wide...........................................................sect. Sagitticarpi
- Pod triquetrous and triangular in section or subterete, twice to many times longer than wide........................................................17
17. Pod stipitate ......................................................................................................................................................................................18
- Pod sessile ........................................................................................................................................................................................19
18. Pod pendulous ................................................................................................................................................................. sect. Miselli
- Pod incurved-ascending...................................................................................................................................... sect. Reventi-Arrecti
19. Pod deflexed; flowers very small, 4–9 mm long, early deflexed, usually very numerous (15–65) ............................ sect. Micranthi
- Pod ascending or loosely spreading; flowers either few or longer than 9 mm, ascending or loosely spreading ................................. ....................................................................................................................................................................................sect. Leptocarpi
20. Plants restricted to Baja California ...................................................................................................................................................21
- Plants throughout Mexico excluding Baja California ......................................................................................................................25
21. Petals large, banner 21–28 mm long; petals of the wings 19.5–25 mm long; keel petals 17.3–21 mm long; in Mexico, recorded only around Mexicali (BC)................................................................................................................................................... sect. Preusiani
- Petals, all shorter; plants around Mexicali and other areas of Baja California ................................................................................22
22. Pod oblong to elliptic, laterally compressed, unilocular, narrowed at both ends, basally ending in a stipe or the pod faces inflated only in the area where seeds are located ..........................................................................................................................................23
- Pod widened or inflated resembling a bladder .................................................................................................................................24
23. Pod oblong to elliptic, laterally compressed, unilocular, narrowed at both ends, basally ending in a stipe .............. sect. Cusickiani
- Pod inflated resembling a bladder, but its faces inflated only in the area where seeds are located ..............................sect. Oxyphysi
24. Plant small, the stems up to 11 cm long; peduncles 0.5–1.5 cm long; petals small, banner 7.3–10 mm long, petals of the wings 7–9.3 mm long, keel petals 6.9–8.8 mm long; mountains of Sierra de Juárez and Sierra de San Pedro Mártir; conifer forest, 1700– 2475 m ....................................................................................................................................................................... sect. Circumdati
- Plants larger, the stems 30–70 cm long; peduncles 2.5–10 cm long; petals larger; coastal dunes............................ sect. Anemophili
25. Pubescence dolabriform, the trichomes joined at a point before the end, in the form of “v” or “t”, with equal or unequal ends ....... ..........................................................................................................................................................................................................26
- Pubescence basifixed with simple trichomes ...................................................................................................................................27
26. Pod deflexed, bilocular, triquetrous, oblong to narrow–oblong; banner 6–8.2 mm long............................................ sect. Hypoleuci
- Pod ascendant, unilocular, inflated resembling a bladder, oblong–elliptic; banner 8.3–11.8 mm long ............................................... .................................................................................................................................................................................... sect. Humistrati
27. Petals all red; banner 22–32 mm long; petals of wings 18–31 mm largo; keel petals 18–27 mm long.....................sect. Sarcocarpi
27. Petals of another color, or if red, combined with another color; banner, wings, and keel of smaller size .......................................28
28. Pubescence of stems, petioles and peduncles dense, hispid to pilose, the trichomes straight extended or retrorse; petals purple; ovules 9–18; pod oblong to narrow-oblong, triquetrous, laterally compressed, glabrous .......................................... sect. Greggiani
- Pubescence of stems, and peduncles hispid to pilose or nearly glabrous, but the trichomes appressed or ascending; pod either or different form, but if the same form, then pubescent or if trichomes extended or retrorse, then the flowers yellow ......................29
29. Pod pendulous, stipitate, sometimes obscurely so............................................................................................................................30
- Pod either deflexed or ascending, always sessile .............................................................................................................................31
30. Body of the pod sharply triquetrous, unilocular; seleniferous, ill scented plants.......................................................... sect. Bisulcati
- Body of the pod mostly obcompressed, dorsally excavated, unilocular to fully bilocular, a septum always present; not of seleniferous soils, scentless plants ...................................................................................................................................................sect. Strigullosi
31. Body of the pod unilocular ......................................................................................................................................... sect. Scytocarpi
- Body of the pod semi or fully bilocular........................................................................................................................sect. Strigulosi
description: Published as part of Castillón, Eduardo Estrada, Quintanilla, José Ángel Villarreal & Salinas, Alfonso Delgado-, 2022, A new section of Astragalus (Fabaceae: Galegeae) from Mexico, pp. 79-86 in Phytotaxa 545 (1) on pages 83-84, DOI: 10.11646/phytotaxa.545.1.6, http://zenodo.org/record/6520428