Trifolium
Fabaceae
clover, trefoil
bean family, pea family
prostrate to erect, glabrous or pubescent.
erect, ascending, decumbent, or prostrate, rarely producing resins.
alternate, odd-pinnate or palmate;
stipules present, persistent, adnate to petiole;
petiolate or sessile;
leaflets 3–9, stipels absent, blade margins usually entire or toothed, rarely lobed, surfaces glabrous or pubescent.
deciduous or persistent, usually alternate, rarely opposite, subopposite, whorled, or clustered on spurs, 1–3-pinnate, rarely palmate or 1–4-foliolate, or phyllodic;
stipules usually present, rarely absent, sometimes spinelike, often adnate to petiole;
petiole usually present, pulvini usually present;
stipels sometimes present;
blade margins lobed, dentate, serrate, or entire.
(1–)25–100+-flowered, racemes, umbelliform, spicate, or headlike, axillary or terminal;
bracts present or absent, connate or distinct;
bracteoles present or absent.
axillary or terminal, racemes, spikes, cymes, panicles, pseudoracemes, umbels, heads, or simple.
papilionaceous;
calyx actinomorphic or zygomorphic, tubular or campanulate, sometimes inflated in fruit, lobes 5;
corolla white, cream, pink, red, purple, or yellow, glabrous;
stamens 10, diadelphous;
anthers basifixed;
pistil linear to lanceolate, style glabrous or pubescent, stigma terminal.
bisexual or unisexual, radially or bilaterally symmetric, papilionaceous, caesalpinioid, or mimosoid, rarely pseudopapilionaceous;
perianth and androecium hypogynous or perigynous;
epicalyx absent;
hypanthium sometimes present;
sepals 5, rarely 4 or 6, connate into a tube, rarely nearly distinct;
petals 5, rarely 4, 6, 1, or 0, distinct or slightly connate proximally;
nectary present or absent, in a ring at base of ovary and staminal column;
stamens (1–)10(–250+), filaments connate into tube enclosing pistil and monadelphous or diadelphous, or distinct;
anthers 2-locular, monomorphic or dimorphic and then alternately basifixed and dorsifixed, dehiscence longitudinal or by pores;
pistil 1, 1-carpellate, free from hypanthium, ovary superior, 1-locular or longitudinally septate and 2-locular (in Astragalus), sometimes with lateral constrictions or transverse septae;
placentation marginal;
style 1, apical;
stigma 1, terminal;
ovules 1–100+, anatropous, hemitropous, or campylotropous.
legumes, sessile or stipitate, cylindric or laterally compressed, lanceolate to elliptic, dehiscent, usually longitudinally, rarely transversely or indehiscent, included in marcescent corolla or slightly exserted, papery, membranous, or leathery, glabrous or pubescent.
legumes or loments, dehiscent or indehiscent, rarely drupes or samaroid.
1–4[–9], globose, ovoid-oblong, mitten-shaped, or reniform, hilum lateral.
1–100+;
endosperm scant or copious;
embryo large, curved or straight.
= 5, 6, 7, 8.
= 6, 7, 8, 9, 10, 11, 12, 16.
Trifolium
Fabaceae
Species ca. 280 (98 in the flora).
In the flora area, Trifolium is superficially similar to Medicago, Melilotus, and Trigonella. Trifolium differs from those genera by persistence of the corolla after anthesis, a legume that is included in or only slightly exserted from the persistent corolla, and distally dilated filaments (H. A. Gleason and A. Cronquist 1991; Wei Z. and M. A. Vincent 2010).
Trifolium has three major centers of diversity: the Mediterranean region of southern Europe, western Asia, and northern Africa; the California region in North America; and the eastern African highlands (M. Zohary and D. Heller 1984). In the New World, diversity is highest in the California region of the United States, the mountainous regions of western North America, and western South America. In North America, a suite of closely related species, centered in the southeastern United States, represents another locus of diversification.
Trifolium consists of subg. Chronosemium (Seringe) Reichenbach and subg. Trifolium; the latter is subdivided into eight sections (N. W. Ellison et al. 2006). Subgenus Chronosemium is represented in the flora area by the Old World species T. aureum, T. campestre, and T. dubium. All native New World species of subg. Trifolium represent a monophyletic lineage, sect. Involucrarium Hooker ex Lojacono. The introduced species of subg. Trifolium represent other sections: sect. Lupinaster (Fabricius) Seringe (T. lupinaster), sect. Trichocephalum W. D. J. Koch (T. subterraneum), sect. Trifoliastrum Gray (T. cernuum, T. glomeratum, T. nigrescens, T. repens, T. retusum, and T. suffocatum), sect. Trifolium (T. alexandrinum, T. angustifolium, T. arvense, T. echinatum, T. hirtum, T. incarnatum, T. lappaceum, T. medium, T. pratense, and T. striatum), and sect. Vesicastrum Seringe (T. fragiferum, T. hybridum, T. ornithopodioides, T. resupinatum, T. tomentosum, and T. vesiculosum). This differs dramatically from the phylogenetic arrangement of M. Zohary and D. Heller (1984), where the genus is subdivided into eight sections, and native New World species are placed in sects. Involucrarium and Lotoidea Crantz (in a narrow sense).
Species of Trifolium have been cultivated for centuries in parts of Europe as forage crops; some species were introduced into the flora area for that purpose. Of these, T. repens appears to have been the earliest introduction, perhaps as early as the mid 1600s (R. N. Mack 2003), and its spread across the continent was very rapid. Other commonly cultivated species include T. hirtum, T. hybridum, T. incarnatum, T. pratense, T. subterraneum, and T. vesiculosum; other species may also be cultivated in North America and may be important regionally (N. L. Taylor 1985; J. M. Gillett and Taylor 2001).
The following species have been mentioned as occurring in the flora area but are excluded as waifs or as only represented by cultivated material: Trifolium ambiguum M. Bieberstein, T. dalmaticum Visiani, T. gemellum Pourret ex Willdenow, T. maritimum Hudson, T. michelianum Savi, T. occidentale Coombe, T. pannonicum Jacquin, T. purpureum Loiseleur-Deslongchamps, T. rubens Linnaeus, T. scabrum Linnaeus, T. spumosum Linnaeus, T. squamosum Linnaeus, and T. stellatum Linnaeus.
Lojaconoa Bobrov 1967, which pertains here, is a later homonym of Lojaconoa Gandoger (Poaceae 1891).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Genera ca. 770, species ca. 20,900 (153 genera, 1345 species in the flora).
Fabaceae are the third-largest angiosperm family after Orchidaceae and Asteraceae (M. J. M. Christenhusz et al. 2017). The closest relatives of Fabaceae appear to be Polygalaceae, Quillajaceae D. Don, and Surianaceae (D. E. Soltis et al. 2011). While the family Fabaceae is strongly supported as monophyletic (Angiosperm Phylogeny Group 2016), subfamilial classification has proven to be more complicated. Historically, Fabaceae (often under the alternative name Leguminosae) were considered easily divided into three groups based on morphological features, especially of flowers (A. Cronquist 1981; see morphology discussion below): the caesalpinioids (Caesalpiniaceae R. Brown, or Fabaceae subfam. Caesalpinioideae de Candolle), the mimosoids (Mimosaceae R. Brown, or Fabaceae subfam. Mimosoideae de Candolle), and the papilionoids (Papilionaceae Giseke [Fabaceae in the strict sense], or Fabaceae subfam. Papilionoideae de Candolle [Faboideae Rudd]). Polyphyly of the caesalpinioids has long been suspected, as have affinities to mimosoids, based on morphological data (R. M. Polhill and J. E. Vidal 1981). Phylogenetic studies have confirmed that mimosoids are embedded within a paraphyletic caesalpinioid clade (A. Bruneau et al. 2001, 2008). Most recently, the Legume Phylogeny Working Group (2017) has recognized six subfamilies: Caesalpinioideae (including a monophyletic “mimosoid clade”), Cercidoideae, Detarioideae, Dialioideae LPWG, Duparquetioideae LPWG, and Faboideae [as Papilionoideae]; Dialioideae and Duparquetioideae do not occur in the flora area. Arrangement of genera in this treatment follows the subfamilial classification of Legume Phylogeny Working Group, with the sequence of genera within the subfamilies adapted from G. P. Lewis at al. (2005).
Leaves in Fabaceae are usually compound, often pinnate or twice-pinnate, but also sometimes palmate; leaves with only one blade are likely derived from ancestral compound leaves and are termed unifoliolate (as in Cercis; S. A. Owens 2000). In some taxa, the rachis in a pinnate leaf is extremely reduced (as in Ladeania), making the leaf superficially appear palmate; these leaves are termed pseudopalmate. A characteristic feature of most legume leaves is the pulvinus (plural pulvini), a jointlike thickening of petioles and petiolules that is involved with leaf movement related to changes in light or moisture availability (nyctinasty; T. M. Rodrigues and S. R. Machado 2007) or touch (thigmonasty; J. Braam 2005). Extrafloral nectary glands may be present on leaves (blades, rachises, or petioles) of some taxa, especially in the Detarioideae and Caesalpinioideae, and these may be stalked or sessile, and of various shapes.
Inflorescences in Fabaceae can consist of a single flower, or flowers may be arranged in spikes or heads, which can be grouped in larger paniculate structures, racemes, pseudoracemes (where each node in the racemelike inflorescence bears several flowers), cymes, panicles, or umbels (umbelliform racemes or pseudoracemes with greatly reduced internodes).
Flowers in Fabaceae are generally five-merous, with more or less distinct petals (which are sometimes differentiated into blade and claw) and often with connate sepals. Floral structure conforms in general to three main types: papilionaceous, caesalpinioid, or mimosoid. Papilionaceous flowers (from Latin papilio, butterfly) are usually bilateral and somewhat perigynous. Sepals are connate, at least at the base, into a tube that sometimes completely encloses the floral bud, with or without lobes at the distal end. The usually five petals are arranged into a keel formed from the innermost (abaxial) pair, the wings, the lateral pair positioned outside the keel, and a banner (sometimes called the standard), which is positioned outermost in the bud, surrounding the other petals. The keel petals may be completely distinct from each other or may be connate at the distal end, while the wing petals are usually distinct from each other. The banner petal, which is often the largest of the petals, may be straight (as in Erythrina), or reflexed at a joint or callous or from its base (as in Maackia). The stamens in a papilionaceous flower are usually ten and may be monadelphous (as in Lupinus) or diadelphous (in a 9 + 1 arrangement, with nine filaments connate into a closed tube or at least partially open sheath surrounding the pistil and one stamen distinct from the others, as in Trifolium) and are not usually long-exserted or the showy part of the flower. The pollen is in monads. Caesalpinioid (or pseudopapilionaceous) flowers are often bilateral (zygomorphic) and perigynous (rarely hypogynous). The sepals in caesalpinioid flowers are distinct or nearly so, imbricate or valvate in bud, or connate into a five-lobed cup or even nearly absent. The petals are usually less obviously organized into keel, wings, and banner. The keel and wings may be positioned as in papilionaceous flowers (as in Cercis), or they may be more widely open and more similar to each other. The banner petal is situated in the bud to the inside of the wing petals and is sometimes smaller than the other petals (as in Caesalpinia). Stamens in caesalpinioid flowers range from one to ten, sometimes more, and are often distinct. They are often shorter than the corolla, though sometimes much longer and showy, and are sometimes heteromorphic, of differing sizes or shapes, sometimes with a mix of fertile and sterile (staminodial) anthers. The pollen is usually in monads. Mimosoid flowers are regular (radially symmetric) and hypogynous or slightly perigynous, and the most distinctive of the floral types, usually small and individually inconspicuous. They are not organized as noted above but instead have corollas that are often connate into a tube, rarely distinct, and valvate (rarely imbricate) in the bud. The sepals are usually connate at the base, usually regular, and often lobed distally. The petals may be shorter than or longer than the calyx. Stamens are distinct from one another or proximally connate, range in number from twice as many as the petals to many, and are usually longer or even very much longer than the perianth and thus are the showiest part of the flower. The pollen is usually in tetrads or polyads (Legume Phylogeny Working Group).
Fruits of Fabaceae are generally legumes, usually 1-carpellate and 1-locular, with seeds positioned marginally, and often dehiscent into two valves at maturity. Legumes can vary greatly in morphology (C. R. Gunn 1984, 1991; J. H. Kirkbride et al. 2003), ranging from flattened laterally (as in Pisum) to inflated at maturity (as in Astragalus crassicarpus), and from a few millimeters to 60 centimeters. They are often dry at maturity but may be fleshy (as in Styphnolobium japonicum), with valves (the two halves of the fruit wall) ranging in texture from thin and fragile to thick and woody. Fruits of some Astragalus species may be partially or completely bilocular, due to intrusion of tissue (the replum) from the dorsal (abaxial) suture (Kirkbride et al.; S. L. Welsh 2007). Some legumes are indehiscent (as in Arachis), while others may open along one or both sutures; some taxa have fruits which are explosively dehiscent (as in Zapoteca); valves may remain flat post-dehiscence or may be twisted. A modified form of legume, the loment, is divided into one-seeded indehiscent sections (sometimes called joints) that break apart from each other at maturity (as in Desmodium); a craspedium is similar, but the one-seeded segments leave behind the replum as they fall away (as in Mimosa pudica). Andira is unusual among North American Fabaceae for its drupelike fruit. A few taxa produce samaroid fruits, such as Dalbergia ecastaphyllum. In addition, some taxa in the flora area have geocarpic fruits (Arachis species; Trifolium amphianthum has geocarpic cleistogamous fruits, in addition to the chasmogamous fruits produced on long, erect peduncles).
Seeds of legumes range in number from one to more than 75, and may be positioned in the fruit parallel, obliquely, or transversely to the length of the fruit (C. R. Gunn, 1991; J. H. Kirkbride et al. 2003). They may possess a true aril (as in Pithecellobium), an aril-like, enlarged funiculus, or these may be absent. The hilum (scar of attachment to the funiculus) is sometimes used in identification, and may vary in outline from V-shaped, to linear or circular, or other shapes, and can be variable in size or conformation. A pleurogram (U-shaped or elliptic line) is often present in mimosoid legumes but is usually absent in other groups. The embryo radicle is usually curved in subfam. Faboideae, and is usually straight in the rest of the subfamilies.
Roots of many Fabaceae bear nodules containing nitrogen-fixing bacteria (rhizobia, in numerous genera) that have coevolved with their hosts, which allow the plants to occupy marginal, nitrogen-poor habitats (D. P. S. Verma and J. Stanley 1989; J. P. W. Young and K. E. Haukka 1996; M. Andrews and M. E. Andrews 2017). Nitrogen fixation by rhizobial symbionts of Fabaceae is ecologically important in natural systems and in agricultural systems.
The economic importance of legumes to humans is second only to that of grasses (J. A. Duke 1981; P. H. Graham and C. P. Vance 2003). Among important legume food crops are the grain legume (pulse) genera Arachis, Cicer, Faba Miller, Glycine, Glycyrrhiza, Lens, Phaseolus, Pisum, Tamarindus, and Vigna, which provide a large portion of the dietary protein requirements and other products to people worldwide. In addition, legume forage crops, including Medicago, Trifolium, and Vicia, are important for production of grazing animals and as nectar sources for bees. Many other genera, such as Albizia, Cassia, Cercis, Delonix, Gleditsia, Laburnum, Lupinus, Robinia, Senna, and Wisteria are grown as ornamental plants. In addition, important lumber trees, such as species of Acacia and Dalbergia, are members of Fabaceae. Natural gums, such as gum Arabic (often from Acacia or Senegalia species) and guar gum [from Cyamopsis tetragonoloba (Linnaeus) Taubert], as well as dyes such as true indigo (from Indigofera tinctoria) and haematoxylin (from Haematoxylum campechianum Linnaeus), are derived from species of Fabaceae.
In the key to genera of Fabaceae, characters and character states are sometimes used that are included in descriptions of taxa within the relevant genera but not in the generic descriptions themselves. Such characters are not usually found as part of a normal genus description (for example, measurements), but they are included in the key because they are useful for identifying some genera within the family.
The following taxa are excluded from the flora due to lack of documentation, because they are waifs that did not become established, or because they are only known from cultivation in the flora area: Carmichaelia R. Brown (D. Isely 1998); Chesneya nubigena (D. Don) Ali (Isely); Cojoba graciliflora (S. F. Blake) Britton & Rose (as Pithecellobium graciliflorum S. F. Blake; R. W. Long and O. Lakela 1971; D. B. Ward 1972; R. P. Wunderlin 1998); Cullen americanum (Linnaeus) Rydberg (P. A. Rydberg 1919–1920; J. K. Small 1933); C. corylifolium (Linnaeus) Medikus (as Psoralea corylifolia Linnaeus; R. R. Tatnall 1946); Hippocrepis comosa Linnaeus (E. T. Wherry et al. 1979; A. F. Rhoads and W. M. Klein 1993); Lotononis bainesii Baker (Wunderlin); Otholobium fruticans (Linnaeus) C. H. Stirton (A. Kellogg 1877; Isely); and Scorpiurus muricatus Linnaeus (Tatnall; Rhoads and Klein; M. D. Cullina et al. 2011).
Recent additions to the flora area that are not treated here include: Callerya reticulata (Bentham) Schot (Florida; http://florida.plantatlas.usf.edu/Plant.aspx?id=4377); Dorycnium hirsutum Seringe (California; E. Dean et al. 2008); Lonchocarpus punctatus Kunth (Florida; R. P. Wunderlin 1998); and Psophocarpus tetragonolobus (Linnaeus) de Candolle (Florida; http://florida.plantatlas.usf.edu/Plant.aspx?id=4403).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Involucres present, composed of free or fused bracts, surpassing pedicels; stipule margins usually dentate or lacerate, sometimes entire. | → 2 |
2. Herbs perennial. | → 3 |
3. Inflorescences 1–9-flowered; involucres incised nearly to base, lobes 2–8; keel petals usually purple-spotted. | T. monanthum |
3. Inflorescences (8–)10–50-flowered; involucres incised to 3/4, lobes 10–12; keel petals not spotted. | → 4 |
4. Calyx lobes subequal, abaxial rarely longer than tube; involucre: lobes sharply and acutely serrate; leaflet blades obovate to elliptic. | T. wormskioldii |
4. Calyx lobes ± equal, abaxial lobe longer than tube; involucre: lobes entire, irregular, bifurcate, or triaristate to lacerate; leaflet blades oblanceolate, obovate, linear, or elliptic. | → 5 |
5. Involucral lobes linear-lanceolate, entire; stipule margins entire; roots stout, branched, rhizomes absent. | T. pinetorum |
5. Involucre lobes triaristate to lacerate, or irregular to bifurcate; stipule margins entire, toothed, or lacerate; roots tuberous or taproots, rhizomes present or absent. | → 6 |
6. Roots tuberous, rhizomes present, elongate, slender; stipule margins entire or slightly lacerate; leaflet blades obovate, oblanceolate, or elliptic. | T. siskiyouense |
6. Roots taproots, slender, rhizomes absent or short; stipule margins toothed or lacerate; leaflet blades linear, elliptic, or obovate. | T. mucronatum |
2. Herbs annual or biennial. | → 7 |
7. Calyx and/or banner inflated in fruit. | → 8 |
8. Banner proximally inflated in fruit, distally twisted. | → 9 |
9. Calyx lobes: apex unbranched, setaceous; calyx longer than corolla. | T. barbigerum |
9. Calyx lobes: apex of at least some branched, flattened or setaceous; calyx equaling or shorter than corolla. | → 10 |
10. Abaxial and lateral calyx lobes conspicuously 2- or 3-fid, segments glabrous, sometimes flattened. | T. cyathiferum |
10. Calyx lobes unbranched or apex inconspicuously 3-fid, segments plumose, not flattened. | → 11 |
11. Corollas usually lavender or purple, sometimes purple with white tips; leaves and stems usually pubescent; seeds 1.6–2 mm. | T. grayi |
11. Corollas yellow; leaves and stems glabrous; seeds 3.1–3.4 mm. | T. jokerstii |
8. Banner inflated entire length in fruit, not distally twisted. | → 12 |
12. Flowers 10–27 mm; leaflet blades oblanceolate, obovate, orbiculate, or rhombic-obovate; involucral lobe apex acuminate, sometimes 2- or 3-fid or 3–5-fid. | → 13 |
13. Calyx tube 1.5–2.5 mm, abaxial lobe apex undivided or 2- or 3-fid; seed coat reticulate. | T. fucatum |
13. Calyx tube 2.5–4 mm, abaxial lobe apex 3–5-fid; seed coat smooth. | T. piorkowskii |
12. Flowers 3–11 mm; leaflet blades lanceolate, linear, obovate, or oblanceolate; involucral lobe apex rounded to truncate, not split. | → 14 |
14. Involucres 3–13 mm, incised 1/2 their length; inflorescences 0.5–1 cm diam.; banners 4–7 mm; herbs 1–30 cm; stems erect or decumbent. | T. depauperatum |
14. Involucres 3–4 mm, lobes incised less than 1/2 their length; inflorescences 1–1.8 × 1.3–1.5 cm; banners 7–9 mm; herbs 15–55 cm; stems erect. | T. hydrophilum |
7. Neither calyx nor banner inflated in fruit. | → 15 |
15. Involucres flattened or cup- or bowl-shaped, when compressed laterally, nearly completely hiding calyces. | → 16 |
16. Involucral lobes entire or slightly toothed proximally; involucres conspicuously villous; corollas ± equal to calyces. | T. microcephalum |
16. Involucral lobes conspicuously toothed; involucres glabrous or sparsely hairy; corollas longer than calyces. | → 17 |
17. Involucres flattened or shallowly bowl-shaped; inflorescences 0.5–0.8 cm; calyx lobes aristate, margins not membranous; early inflorescences hidden in stipules, subsessile, with 2–5 cleistogamous flowers. | T. buckwestiorum |
17. Involucres cup-shaped; inflorescences 0.8–1.7 cm; calyx lobes not or minutely aristate, margins membranous; early inflorescences not hidden, without cleistogamous flowers. | T. microdon |
15. Involucres rotate, bracts sometimes separate, or involucres flattened to bowl- or vase-shaped, when compressed laterally, not hiding flowers except proximally. | → 18 |
18. Calyx tubes slit between adaxial lobes, lobes shorter than or equal to tube, 3-fid or shouldered below subulate apex (usually entire in T. obtusiflorum); leaflet blades linear, oblong, lanceolate, oblanceolate, elliptic, rhombic, or obovate. | → 19 |
19. Flowers 11–16 mm; involucres 1–2 mm, incised 4/5–9/10 their length, lobes not lacerate; inflorescences 0.3–0.8 cm diam., 3–15-flowered. | T. oliganthum |
19. Flowers 12–20 mm; involucres 3–9 mm, incised 1/4–1/3 their length, lobes deeply lacerate; inflorescences 1–3 cm diam., 10–50-flowered. | → 20 |
20. Peduncles and calyces glabrous; calyx lobes usually 3-fid or shouldered; leaflet margins serrate. | T. willdenovii |
20. Peduncles and calyces glandular; calyx lobes usually entire, rarely 3-fid or shouldered; leaflet margins coarsely spinulose-serrate. | T. obtusiflorum |
18. Calyx tubes not slit between adaxial lobes, lobes longer than tube, usually entire and without shoulders, rarely 3-fid or laciniate; leaflet blades obovate to oblanceolate, or elliptic. | → 21 |
21. Calyces usually densely pubescent; involucres flattened or vase-shaped, 1–3 mm, incised 2/3–3/4 their length; seeds 3–6(–9). | T. trichocalyx |
21. Calyces glabrous; involucres flattened or bowl-shaped, 4–16 mm, incised 1/2 their length; seeds 1 or 2. | → 22 |
22. Calyx lobes 3-fid or laciniate; leaflet blades broadly elliptic to broadly obovate, apex rounded or truncate, often retuse; stems decumbent or ascending; Monterey Peninsula, California. | T. polyodon |
22. Calyx lobes entire (rarely with a small, lateral tooth); leaflet blades elliptic, obovate, or oblanceolate, apex acute or retuse; stems usually erect or ascending, rarely decumbent; w North America. | → 23 |
23. Banner petals 3.2–9.7 mm, included or exserted 0.1–5.7 mm beyond tips of calyx lobes, keel petals not beaked; mature seeds 1.1–1.6 mm; Alaska and British Columbia south to California, east to Arizona and Montana. | T. variegatum |
23. Banner petals 6.3–15.8 mm, exserted 1.5–8.4 mm beyond tips of calyx lobes, keel petals beaked or not; mature seeds 1.9–2.8 mm; California, s Oregon. | T. appendiculatum |
1. Involucres absent or vestigial, not exceeding pedicels, or if better developed, then formed of bracteoles, or with subtending leaves and stipules forming involucrelike structures; stipule margins usually entire, lobed, or toothed, sometimes serrate or denticulate. | → 24 |
24. Calyces and/or corollas inflated in fruit; legumes usually shorter than calyces. | → 25 |
25. Calyces not bilabiate in fruit, veins 5 or 20–36; involucres absent or vestigial. | → 26 |
26. Calyces inflated in fruit, corollas not inflated in fruit; tubes of fruiting calyces with interconnecting veins; involucres absent; bracteoles present, nearly equaling calyces; herbs 15–70 cm. | T. vesiculosum |
26. Calyces not inflated in fruit, corollas inflated in fruit; tubes of fruiting calyces without interconnecting veins; involucres vestigial, reduced to narrow ring; bracteoles absent; herbs 1–30 cm. | T. depauperatum |
25. Calyces markedly bilabiate in fruit, veins 5–10; involucres of bracteoles or a narrow rim. | → 27 |
27. Herbs perennial; stems prostrate or creeping; flowers not resupinate; involucres of bracteoles cup-shaped, 3–6 mm. | T. fragiferum |
27. Herbs annual; stems prostrate, procumbent, ascending, or erect; flowers resupinate; involucres a narrow rim, 0.2 mm. | → 28 |
28. Inflorescences forming stellate-spreading clusters of calyces in fruit; calyces short-hairy or glabrescent in fruit, orifices open, lobes erect or divergent. | T. resupinatum |
28. Inflorescences not forming stellate-spreading clusters in fruit; calyces densely white-woolly, orifices abruptly constricted in fruit, adaxial lobes spreading or curved. | T. tomentosum |
24. Calyces and corollas not inflated in fruit; legumes longer than or equal to calyces. | → 29 |
29. Calyx lobes: abaxial lobes longer, adaxial very short; banner spatulate, boat-shaped, or obovate; legumes stipitate, seeds 1 or 2. | → 30 |
30. Terminal leaflets sessile; stipules 0.9–1.5 cm; banners: apex emarginate. | T. aureum |
30. Terminal leaflets obviously stalked; stipules 0.3–0.8 cm; banners: apex rounded or broadly acute. | → 31 |
31. Stipules 0.3–0.5 cm; flowers 2.8–3.5 mm; leaflet blades obovate to elliptic-lanceolate; corollas not or slightly ribbed. | T. dubium |
31. Stipules 0.5–0.8 cm; flowers 4.3–5 mm; leaflet blades rhombic to obovate; corollas obviously ribbed. | T. campestre |
29. Calyx lobes: abaxial ± equaling adaxial, or if lobes markedly unequal, then banner not spatulate or boat-shaped; legumes sessile or stipitate, seeds 1–9. | → 32 |
32. Inflorescences with 2–7 fertile flowers with corollas and 0–80 sterile flowers without corollas; inflorescences pedunculate, pushing into substrate in fruit, subterranean flowers chasmogamous. | T. subterraneum |
32. Inflorescences with 1–100+ fertile flowers with corollas; inflorescences not pushing into substrate in fruit, if so (T. amphianthum only), subterranean inflorescences sessile and subterranean flowers cleistogamous. | → 33 |
33. Pedicels 0–1 mm; bracteoles usually absent (present in T. arvense); calyx orifices thickened or closed by callosity or ring of hairs; legumes leathery distally, transversely dehiscent; seeds 1 or 2. | → 34 |
34. Calyx veins 20. | → 35 |
35. Calyces pilose; peduncles 0 cm; inflorescences appearing involucrate (involucrelike structures formed by enlarging stipules), disarticulating in fruit. | T. hirtum |
35. Calyces glabrous; peduncles 0.1–0.7 cm; inflorescences not involucrate, burlike, not disarticulating in fruit. | T. lappaceum |
34. Calyx veins 10–20 or not distinguishable. | → 36 |
36. Flowers 5–8 mm. | → 37 |
37. Leaflet blades broadly ovate or obovate to oblong, lengths 1–1.5(–2) times widths; calyx 3–4 mm. | T. striatum |
37. Leaflet blades elliptic, oblong, linear-oblong, linear-lanceolate, or obovate, lengths usually (2.5–)3–7 times widths; calyx 5–8 mm. | T. arvense |
36. Flowers 9–18 mm. | → 38 |
38. Herbs perennial. | → 39 |
39. Peduncles ± 0 mm, hidden by stipules of distal leaves; calyx tubes hairy; stipules broadly triangular, apex mucronate or setaceous. | T. pratense |
39. Peduncles 1–3 cm, not hidden by subtending stipules; calyx tubes glabrous; stipules lanceolate-linear, apex subulate. | T. medium |
38. Herbs usually annual, rarely biennial. | → 40 |
40. Leaflet blades broadly ovate or obovate to oblong, lengths 1–1.5(–2) times widths; corollas usually scarlet to red, rarely pink or white, banner oblong-elliptic, apex acute. | T. incarnatum |
40. Leaflet blades elliptic, oblong, linear-oblong, linear-lanceolate, or obovate, lengths usually (2.5–)3–7 times widths; corollas usually whitish, pale pink, or purple, banner narrowly-spatulate, oblong-spatulate, or ovate-elliptic, apex acute, obtuse, or notched. | → 41 |
41. Corollas shorter than or equaling calyx, usually pale pink or purple, rarely white; inflorescences 3–8 cm; calyx 8–13 mm, orifices closed by bilabiate callosities. | T. angustifolium |
41. Corollas longer than calyx, whitish; inflorescences 1–2.5 cm; calyx 6–8 mm, orifices open or closed by bilabiate callosities. | → 42 |
42. Calyx orifices closed by bilabiate callosities, lobes unequal, triangular-elliptic, stellate-spreading, tubes glabrescent; corollas 8–10 mm; banner apex acute; seeds 1.2–1.4 mm. | T. echinatum |
42. Calyx orifices open, hairy, lobes equal or abaxial 2 slightly longer, narrowly triangular, erect to slightly spreading, tubes appressed-hairy; corollas 13–16 mm; banner apex obtuse; seeds 2–2.2 mm. | T. alexandrinum |
33. Pedicels (0–)1–8(–12) mm; bracteoles usually present; calyx orifices open; legumes not leathery distally, longitudinally dehiscent; seeds 1–9. | → 43 |
43. Calyces glabrous. | → 44 |
44. Herbs perennial; stems creeping, rooting at nodes; peduncles erect, from prostrate stems; pedicels strongly reflexed in fruit; corollas equaling or 2 times calyces. | T. repens |
44. Herbs annual or perennial; stems usually erect or ascending, rarely prostrate, not rooting at nodes; peduncles erect or not, from prostrate or upright stems; pedicels reflexed or not; corollas shorter to longer than calyces. | → 45 |
45. Corollas 2+ times calyces. | → 46 |
46. Pedicels erect or slightly reflexed, sometimes only those of proximal flowers reflexed. | → 47 |
47. Calyx lobes curved or twisted. | → 48 |
48. Herbs annual; stems procumbent, decumbent, or ascending; inflorescences 0.8–1 cm diam.; peduncles 0–0.1 cm. | T. glomeratum |
48. Herbs perennial; stems erect; inflorescences 2–3.5 cm diam.; peduncles 3–12 cm. | T. douglasii |
47. Calyx lobes straight. | → 49 |
49. Herbs 4–10 cm; stems mat-forming, cespitose; flowers 1–4; bracteoles membranous, connate, forming cuplike involucres. | T. nanum |
49. Herbs 10–20 cm; stems erect or ascending, loosely cespitose or rhizomatous; flowers 15–20; bracteoles purplish, scarious, sometimes connate, forming involucres. | T. parryi |
46. Pedicels strongly reflexed. | → 50 |
50. Inflorescences: rachises not prolonged beyond flowers, without sterile flowers. | T. hybridum |
50. Inflorescences: rachises prolonged beyond (fertile) flowers, often bearing a cluster of sterile flower buds distally. | → 51 |
51. Stems 30–100 cm, fistulose; leaflet blades 2.3–5 cm wide. | T. howellii |
51. Stems 5–50 cm, not fistulose; leaflet blades 0.1–2 cm wide. | → 52 |
52. Calyx veins 5. | → 53 |
53. Peduncles thick, straight; banners straight, obovate to broadly elliptic. | T. beckwithii |
53. Peduncles slender, bent distally just below flowers; banners curved, oblanceolate. | T. bolanderi |
52. Calyx veins 10 (5 sometimes faint). | → 54 |
54. Stems ± erect, loosely cespitose; leaves basal and cauline. | → 55 |
55. Leaflet blades lanceolate or elliptic; calyces 3–3.5 mm. | T. productum |
55. Leaflet blades lanceolate to linear; calyces 6–8.5 mm. | T. dedeckerae |
54. Stems ascending, cespitose; leaves mostly basal. | → 56 |
56. Inflorescences globose or subglobose; peduncles straight proximal to flowers; corollas salmon, buff-pink, or pink, with white or cream tips; calyx lobes equaling tubes. | T. haydenii |
56. Inflorescences hemispheric; peduncles curved distally, just below flowers, inflorescences appearing turned to one side; corollas purple, often white-tipped; calyx lobes shorter than tubes. | T. rollinsii |
45. Corollas less than 2 times calyces. | → 57 |
57. Pedicels straight or slightly reflexed in fruit. | → 58 |
58. Inflorescences loose, flowers 1–5, not overtopped by leafy stipules; calyx lobes straight in fruit. | T. ornithopodioides |
58. Inflorescences dense, flowers 10–20, overtopped by broad, membranous stipules; calyx lobes curved in fruit. | T. suffocatum |
57. Pedicels strongly reflexed or recurved in fruit. | → 59 |
59. Calyx lobes recurved in fruit. | → 60 |
60. Peduncles equaling or shorter than subtending leaves; stipule apex stramineous; corollas shorter than calyces. | T. retusum |
60. Peduncles longer than subtending leaves; stipule apex dark purple or reddish; corollas longer than calyces. | T. nigrescens |
59. Calyx lobes not recurved (except T. nigrescens) in fruit. | → 61 |
61. Calyx lobe margins hyaline, dentate or pectinate, markedly ciliate. | T. ciliolatum |
61. Calyx lobe margins green, purple, or pink, not dentate or pectinate, not ciliate. | → 62 |
62. Leaflet blades narrowly obcordate, obovate, oblanceolate, or linear, apex, at least some, retuse to deeply 2-fid. | T. bifidum |
62. Leaflet blades narrowly elliptic, lanceolate, obovate, obcordate, ovate, oblong, rhombic, or broadly elliptic, apex not 2-fid, sometimes shallowly retuse. | → 63 |
63. Leaflet blades narrowly elliptic or lanceolate, apex acute; calyx lobe margins membranous. | T. palmeri |
63. Leaflet blades obovate to obcordate or ovate, oblong, or rhombic, apex broadly rounded, broadly acute, truncate, emarginate, or retuse; calyx lobe margins not membranous. | → 64 |
64. Peduncles 0.6–1.5 cm, distal ones shorter; flowers 4–5.5 mm; banners: apex deeply emarginate. | T. cernuum |
64. Peduncles 1–9 cm; flowers 5–15 mm; banners: apex rounded, retuse, apiculate, erose-denticulate, or acute. | → 65 |
65. Calyx lobes (at least most) equaling to less than 2 times tube; stipule apex subulate, sharply recurved, dark purple or reddish. | T. nigrescens |
65. Calyx lobes 2 times tube; stipule apex acute or acuminate, usually erect, green. | → 66 |
66. Inflorescences 0.5–2 cm diam.; calyx lobes unequal, long-triangular; stipules ovate-lanceolate, membranous; corollas 5–8 mm; bracteoles cuplike. | T. gracilentum |
66. Inflorescences 2–4 cm diam.; calyx lobes equal, narrowly triangular to subulate; stipules broadly ovate, foliaceous; corollas 9–14 mm; bracteoles broad-obovate, truncate to 2-fid. | T. reflexum |
43. Calyces entirely or partly pubescent. | → 67 |
67. Inflorescences 4–30(–50)-flowered. | → 68 |
68. Pedicels erect or only those of proximal flowers reflexed in fruit. | → 69 |
69. Peduncles ± 0 cm, inflorescences largely hidden by broad, membranous stipules; herbs 3–10 cm; pedicels 0.1 mm. | T. suffocatum |
69. Peduncles (0–)1–17 cm, usually not hidden by stipules (partially hidden in T. macraei); herbs 0.8–30 cm; pedicels (0–)0.5–4 mm. | → 70 |
70. Leaflets 3 or 5(–9); stipule margins entire, irregularly dentate, or serrate. | → 71 |
71. Stipule margins finely and sharply serrate; stems erect, unbranched or branched distally; Alaska. | T. lupinaster |
71. Stipule margins entire or irregularly dentate; stems cespitose, numerous, short, branched from woody crown; Oregon to Montana, southward to California and New Mexico. | T. gymnocarpon |
70. Leaflets 3; stipule margins entire. | → 72 |
72. Inflorescences usually in pairs, partially hidden by terminal leaves and stipules; peduncles 0–0.2 cm; pedicels 0 mm. | T. macraei |
72. Inflorescences single, not hidden by terminal leaves and stipules; peduncles 1–17 cm; pedicels 0.5–3.5 mm. | → 73 |
73. Herbs canescent; leaflet blades oblanceolate to obovate, often folded, surfaces densely silvery-hairy; bracteoles absent; banners 8–10 mm, oblong, apex acute. | T. friscanum |
73. Herbs glabrous or pubescent, not canescent; leaflet blades oblong-elliptic, oblanceolate, or obovate, sometimes folded, surfaces glabrous or hairy; bracteoles linear-lanceolate; banners 11–15 mm, broadly elliptic-ovate, apex rounded, apiculate. | T. dasyphyllum |
68. Pedicels curved or reflexed in fruit. | → 74 |
74. Peduncles ± geniculate distally. | → 75 |
75. Calyx tubular, lobes subequal, subulate. | T. breweri |
75. Calyx campanulate, bilabiate, lobes markedly unequal, adaxial longer than abaxial, foliaceous. | → 76 |
76. Calyx lobes, except abaxial, obovate, veins reticulate, surfaces glabrous, sparsely pilose marginally. | T. bejariense |
76. Calyx lobes broadly triangular, veins slightly branched, surfaces villous. | T. carolinianum |
74. Peduncles straight. | → 77 |
77. Stems creeping, rooting at nodes; inflorescences 2 kinds, one aerial, long-pedunculate, flowers chasmogamous, other subterranean, flowers cleistogamous. | T. amphianthum |
77. Stems not creeping, not rooting at nodes; inflorescences aerial, flowers chasmogamous. | → 78 |
78. Herbs annual or biennial; stems not cespitose. | → 79 |
79. Calyx lobe margins dentate or pectinate, ciliate. | T. ciliolatum |
79. Calyx lobe margins entire. | → 80 |
80. Leaflet blades narrowly obcordate, obovate, oblanceolate, or linear, at least some with apex retuse to deeply 2-fid; flowers 6–8 mm; banners elliptic to oblong, apex rounded, apiculate. | T. bifidum |
80. Leaflet blades ovate, obovate, oblong, rhombic, or orbiculate, apex acute, rounded, emarginate, or obcordate; flowers 9–15 mm; banners obovate-oblong or ovate-oblong, apex usually rounded or retuse, sometimes erose-denticulate. | → 81 |
81. Stems erect or ascending; distalmost petioles 0.3–3.5 cm; calyx lobes 3–7 mm. | T. reflexum |
81. Stems decumbent; distalmost petioles 6–8 cm; calyx lobes 2–3.7 mm. | T. kentuckiense |
78. Herbs perennial; stems mostly cespitose. | → 82 |
82. Inflorescence rachises not surpassing distalmost flowers. | → 83 |
83. Herbs pubescent, 5–30 cm; stems erect or ascending; stipules 1.8–2 cm; leaflet blades 1.5–6 cm, margins entire; flowers 15–22 mm; corollas red-purple. | T. attenuatum |
83. Herbs mostly glabrous, 3–5 cm; stems densely matted; stipules 0.5–1 cm; leaflet blades 0.3–1.6 cm, margins sharply antrorsely serrate; flowers 8–13 mm; corollas creamy white. | T. barnebyi |
82. Inflorescence rachises surpassing distalmost flowers. | → 84 |
84. Calyx 7–10 mm, lobes narrowly triangular, acuminate, length less than 2 times tube; corollas 15–18 mm; leaflet margins entire. | T. brandegeei |
84. Calyx 3.3–15 mm, lobes narrowly triangular, linear, or subulate, length 2+ times tube; corollas 5.3–20 mm; leaflet margins entire, serrate, or serrulate. | → 85 |
85. Stems prostrate; stipule margins entire or finely serrulate; leaflet blades obovate to obcordate, largest to 1.6 × 1.2 cm; bracteoles linear-triangular, 0.5 mm; flowers 5.7–6.7 mm; banners obovate, apex broadly rounded or broadly acute. | T. sonorense |
85. Stems ascending; stipule margins entire proximally, 1–3-toothed distally; leaflet blades obovate or elliptic, largest to 4.2 × 2.5 cm; bracteoles scalelike, to 0.3 mm; flowers 13–17 mm; banners elliptic, apex tapered, sometimes retuse. | T. latifolium |
67. Inflorescences (5–)10–50(–80)-flowered. | → 86 |
86. Petioles 0.5–0.7 cm; stipules adnate to petioles, sheathing; leaflets (3–)5(–9). | T. lupinaster |
86. Petioles (0.3–)1–20(–25) cm; stipules not adnate to petioles, not sheathing; leaf-lets 3 or 5–9. | → 87 |
87. Leaflets 5–9. | → 88 |
88. Inflorescences 2.5–8 × 3–7 cm; calyx lobes 2–4 times tube. | → 89 |
89. Leaflets 5–7, blades linear, linear-lanceolate, or linear-elliptic, 2–7 cm; inflorescences 3–5 × 3–4 cm; calyx lobes slightly pilose; corollas rose-pink to purple. | T. thompsonii |
89. Leaflets (5–)7–9, blades broadly to narrowly obovate, 1–2.7 cm; inflorescences 2.5–8 × 3–7 cm; calyx lobes plumose; corolla white, creamy white, or pinkish, keel petals deep pink. | T. macrocephalum |
88. Inflorescences 1–3 × 1–3 cm; calyx lobes shorter than or to 1.5 times tube. | → 90 |
90. Pedicels 0 mm; calyces 9–11 mm; leaflet margins entire; seeds 1.6–2 mm. | T. andersonii |
90. Pedicels 1–4 mm; calyces 3–7.5 mm; leaflet margins dentate; seeds 2.5–4.5 mm. | → 91 |
91. Flowers 6–15, 7.5–13 mm; peduncles 1–6.5 cm, ± surpassing leaves, not bent distally; inflorescences 1–2 cm. | T. gymnocarpon |
91. Flowers 15–30, 11–13 mm; peduncles 5–15 cm, surpassing leaves, sharply bent distally, just below flowers; inflorescences 2–3 cm. | T. lemmonii |
87. Leaflets 3. | → 92 |
92. Pedicels absent or not all reflexed in fruit. | → 93 |
93. Leaflet blade lengths 3+ times widths. | → 94 |
94. Bracteoles conspicuous, 2–6 mm, proximal ones sometimes connate, forming involucre; banners broadly elliptic-ovate, folded distally, apex rounded, apiculate; ovaries pubescent distally. | T. dasyphyllum |
94. Bracteoles inconspicuous, 0–0.5 mm, not forming involucre; banners oblong or ovate to oblanceolate, apex usually acute or obtuse, rarely rounded or truncate; ovaries glabrous or pubescent distally. | → 95 |
95. Calyx veins 15–20; ovaries glabrous or pubescent distally. | → 96 |
96. Leaflet blades often folded, falcate; inflorescences spicate, ovoid to cylindric; calyx lobes subulate, straight. | T. plumosum |
96. Leaflet blades flat, not falcate; inflorescences umbellate, globose to ovoid; calyx lobes triangular or subulate, lateral and adaxial tortuous, curved downwards and inwards around corollas, abaxial straight. | T. douglasii |
95. Calyx veins 5–10; ovaries pubescent distally. | → 97 |
97. Peduncles 0.1–1 cm; inflorescences usually formed of 2 sessile heads, subtended by distal stipules and leaves, forming involucrelike structure, or involucre absent; stipules oblanceolate, margins entire; calyx rough-hairy or glabrous, lobes subequal. | T. andinum |
97. Peduncles 1–30 cm; inflorescences: distal stipules not forming involucrelike structure; stipules ovate to lanceolate, margins usually entire, sometimes slightly serrate proximally; calyx hairy or glabrous, lobes unequal. | T. longipes |
93. Leaflet blade lengths to 2 times widths. | → 98 |
98. Herbs perennial; stems erect or spreading, cespitose, little branched distally. | → 99 |
99. Stipules fused at base, broadly obovate, margins slightly lobed; leaflets slightly overlapping, blades ovate, obovate, or orbiculate, apex emarginate. | T. owyheense |
99. Stipules distinct at base, ovate to lanceolate, margins usually entire, sometimes slightly serrate proximally; leaflets not overlapping, blades linear, lanceolate to elliptic, or oblong, cauline sometimes ovate, apex acute. | T. longipes |
98. Herbs annual; stems erect, ascending, or prostrate, not cespitose, branched throughout or unbranched. | → 100 |
100. Peduncles 0–0.2 cm; inflorescences usually paired, sometimes one head slightly stalked, partially hidden by terminal leaves and stipules. | T. macraei |
100. Peduncles 0.5–15 cm; inflorescences single, not hidden by terminal leaves or stipules. | → 101 |
101. Calyces campanulate, veins 10 (additional faint veins sometimes present), sinuses rounded, lobes divergent; corollas shorter than calyces. | T. albopurpureum |
101. Calyces tubular, veins 20–30, sinuses acute, lobes not divergent, appearing rigidly erect; corollas shorter or longer than calyces. | → 102 |
102. Corollas shorter than calyces or absent. | T. columbinum |
102. Corollas longer than calyces. | → 103 |
103. Inflorescences bluntly conic, ellipsoid, globose, or subglobose, 1.5–3 × 1.5–2.5 cm; leaflet blades broadly obovate or elliptic, 1.7–3.3 × 1.1–2 cm; corollas 12–16 mm; calyces 9–12 mm. | T. amoenum |
103. Inflorescences ovoid-ellipsoid, 1.1–2.2 × 1–1.5 cm; leaflet blades obovate or oblanceolate, 0.5–1.5 × 0.2–1.1 cm; corollas 7–12 mm; calyces 4–8 mm. | T. dichotomum |
92. Pedicels reflexed in fruit. | → 104 |
104. Herbs perennial; stems creeping, rooting at nodes. | → 105 |
105. Inflorescences of 2 kinds: one terminal, aerial, long-pedunculate, flowers chasmogamous, the other basal, subterranean, flowers cleistogamous. | T. amphianthum |
105. Inflorescences all aerial, flowers chasmogamous. | → 106 |
106. Peduncles 2–7 cm, single or paired at tips of erect stems, subtended by pair of opposite or subopposite, short-petiolate leaves; inflorescences 2–3.5 × 2–3.5 cm; flowers 15–30; leaflet blades broadly ovate or obcordate. | T. stoloniferum |
106. Peduncles 10–12 cm, single, arising from stolons; inflorescences 1.8–2.2 × 1.8–2.2 cm; flowers 25–50; leaflet blades obovate, rhombic, or elliptic. | T. calcaricum |
104. Herbs annual, biennial, or perennial; stems not creeping, not rooting at nodes. | → 107 |
107. Leaflet lengths 3+ times widths. | → 108 |
108. Herbs annual; leaflet blades narrowly obcordate, obovate, oblanceolate, or linear, apex rounded or truncate, shallowly to deeply retuse or deeply 2-fid. | T. bifidum |
108. Herbs perennial; leaflet blades elliptic, linear-elliptic, lanceolate, oblong, ovate, or linear, apex not deeply retuse to 2-fid. | → 109 |
109. Peduncles bent or curved proximal to flowers, inflorescences inverted or horizontal. | → 110 |
110. Ovaries pubescent distally; calyx curved in fruit, lobes unequal, lengths 2–3 times tube, plumose. | T. eriocephalum |
110. Ovaries glabrous; calyx straight, lobes equal, lengths 1–1.5 times tube, sparsely pubescent or glabrate. | T. kingii |
109. Peduncles straight, inflorescences erect. | → 111 |
111. Banners ovate to oblanceolate, apex tapering, acuminate or beaked. | T. longipes |
111. Banners broadly oblong-elliptic or obovate-oblong, apex rounded, acute, or retuse, sometimes mucronate or apiculate. | → 112 |
112. Leaflet blade apex narrowly acute or acuminate, margins entire; proximal bracteoles forming involucres; flowers 10–20; calyces 8–15 mm; w United States. | T. attenuatum |
112. Leaflet blade apex truncate to acute, margins entire or serrulate; bracteoles not forming involucres; flowers 20–40; calyces 4–7 mm; e United States. | T. virginicum |
107. Leaflet lengths usually to 2 times widths. | → 113 |
113. Herbs annual or biennial. | → 114 |
114. Calyces markedly bilabiate, lobes markedly unequal (adaxial longer than abaxial), oblong-ovate or broadly triangular, veins reticulate or branched. | → 115 |
115. Calyx lobes, except abaxial, obovate, pubescent along margins, veins reticulate. | T. bejariense |
115. Calyx lobes broadly triangular, lanceolate, or linear, uniformly villous, veins slightly branched. | T. carolinianum |
114. Calyces not markedly bilabiate, lobes ± equal, triangular, lanceolate or linear, or subulate, veins unbranched. | → 116 |
116. Inflorescence rachises not surpassing flowers; stipule apex recurved, dark purple or reddish; calyx lobes recurved in fruit. | T. nigrescens |
116. Inflorescence rachises sometimes surpassing flowers; stipule apex straight, green; calyx lobes straight in fruit. | → 117 |
117. Calyx lobes unequal, margins dentate or pectinate, strongly ciliate, sinuses narrow; inflorescences 0.5–2 cm diam.; seeds 2.5–3 mm. | T. ciliolatum |
117. Calyx lobes equal, margins entire, sinuses broad; inflorescences 2–4 cm diam.; seeds 1.2–1.5 mm. | T. reflexum |
113. Herbs perennial. | → 118 |
118. Herbs canescent; margins of stipules and leaflets coarsely spinulose-dentate. | T. leibergii |
118. Herbs glabrous or pubescent, not canescent; margins of stipules and leaves entire or toothed, not spinulose. | → 119 |
119. Inflorescence rachises not surpassing flowers; banners ovate-oblong, apex rounded-denticulate. | T. hybridum |
119. Inflorescence rachises sometimes surpassing flowers; banners elliptic, obovate, ovate-oblong, or lanceolate-ovate, apex not denticulate. | → 120 |
120. Peduncles geniculate or bent proximal to flowers, inflorescences appearing inverted. | → 121 |
121. Stipule apex long-acuminate, margins entire; corollas 6–10 mm; banners equaling wing and keel petals. | T. breweri |
121. Stipules apex acuminate or acute, margins entire proximally, 1–3-toothed distally; corollas 12–15 mm; banners longer than wing and keel petals. | T. latifolium |
120. Peduncles straight, inflorescences erect. | → 122 |
122. Herbs pubescent; stems prostrate; leaflet blades obovate to obcordate, 0.9–1.6 cm; inflorescences 0.8–1.6 × 0.9–1.6 cm. | T. sonorense |
122. Herbs glabrous; stems erect, ascending, or decumbent; leaflet blades ovate, rhombic, elliptic, or lanceolate, 0.5–8 cm; inflorescences 1.5–4 × 1.4–3.5 cm. | → 123 |
123. Inflorescences longer than wide, rachis internodes between floral whorls elongated; leaflet blades of basal leaves thin, margins setose to dentate. | T. macilentum |
123. Inflorescences ± as long as wide, rachis internodes not especially elongated; leaflet blades of basal leaves thick, margins sometimes shortly setose. | T. kingii |
Key to Subfamilies
1. Flowers usually papilionaceous and bilaterally symmetrical (rarely not conventionally papilionaceous, only banner present or cleistogamous flowers enclosed in calyx), sometimes radially symmetrical, banner outermost; sepals connate, at least at base; seeds with a complex hilar valve; pleurogram absent; embryo radicle usually curved. | Faboideae |
1. Flowers usually mimosoid or caesalpinioid, rarely pseudopapilionaceous, not papilionaceous, either bilaterally or radially symmetrical, banner innermost or petals valvate (in mimosoid clade); sepals distinct or connate; seeds without complex hilar valve, pleurogram present or absent; embryo radicle usually straight. | → 2 |
2. Leaves bipinnate, rarely pinnate or phyllodic; flowers radially symmetric, usually small and individually inconspicuous; inflorescences usually heads or spikes, sometimes racemes, panicles, capitula, or umbels; seeds usually with an open or closed pleurogram on each side; petals valvate in bud; sepals usually connate at base; stamens usually 5–10(–250), usually exserted beyond petals; pollen commonly in tetrads or polyads; root nodules present; embryo straight. | Caesalpinioideae, mimosoid clade |
2. Leaves pinnate, bipinnate, or unifoliolate, rarely bifoliolate; flowers bilaterally symmetric or irregular, usually larger and individually conspicuous; inflorescences usually racemes, rarely panicles; seeds without an open or closed pleurogram on either side; petals imbricate in bud; sepals usually distinct; stamens (1–)3–10, usually not exserted beyond petals; pollen in monads; root nodules rarely present; embryo straight or curved. | → 3 |
3. Leaves unifoliolate, bilobed or entire, or compound and 2-foliolate; seed hilum circular or crescent-shaped. | Cercidoideae |
3. Leaves pinnate or bipinnate; seed hilum not crescent-shaped, rarely circular. | → 4 |
4. Extrafloral nectaries and other glandular structures (when present) on lower surface or margin of leaflets; stipules usually intrapetiolar, distinct, rarely lateral; stamens usually included in corolla, monadelphous, anthers dorsifixed, longitudinally dehiscent; legumes pulpy, indehiscent; (1 species, Tamarindus indica, large unarmed trees introduced into south Florida). | Detarioideae |
4. Extrafloral nectaries usually present on petiole or on leaf rachis, usually between pinnae pairs; stipules lateral and distinct or absent; stamens usually exserted from corolla, filaments distinct, anthers basifixed or dorsifixed, dehiscing by apical pores or lateral slits; legumes dry, dehiscent on one or both sutures or indehiscent. | Caesalpinioideae, excluding mimosoid clade |
CA
WA
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