Lotus

Taxonomy

Lotus C. Linnaeus Sp. Pl. 773. 1 Mai 1753.

Subfamily: Faboideae.
Phylogenetic Number: 3.13.07.
Tribe: Loteae.
Species Studied - Species in Genus: 62 studied; ca. 100 in genus.

Description

Fruit: A legume; unilocular; 2.5–9 cm long; 0.2–0.8 cm wide; 0.2–0.3 cm thick; 2–9 times longer than wide, or more than 9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with deciduous calyx, or persistent calyx; with calyx shorter than fruit; without orifice formed by curving of fruit or fruit segments; straight, or curved (or slightly curved); not plicate; not twisted; symmetrical, or asymmetrical; linear, or oblong, or falcate; with both sutures parallelly curved, or both sutures nearly straight; not inflated; terete, or compressed; without beak; short tapered at apex, or rounded at apex; aligned with longitudinal axis of fruit; short tapered at base, or rounded at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous; seed chambers externally visible, or invisible; seed chambers with the raised seed chambers not torulose, or torulose; margin not constricted, or constricted; margin slightly constricted along both margins; margin without sulcus; margin plain, or embellished; margin with wing(s); wing(s) absent, or present (section Tetragonolobus); wing(s) 2, or 4 (with 2 wings on long upper suture and none below, or 2 wings along both sutures); wing(s) 1–2 mm wide; wing(s) sutural; wing(s) on both sutures, or 1 suture; nonstipitate; with all layers dehiscing, or indehiscent (rarely); splitting along suture(s). Dehiscence of valves along both sutures; apical and down; passive, or active; with valves twisting, or enrolling. Replum invisible. Epicarp dull; monochrome; reddish brown; with surface texture uniform; glabrous, or pubescent and indurate; with hairs appressed; with 1 type of pubescence; with pubescence golden; with pubescence uniformly distributed; with simple hairs; pliable; with hair bases plain; eglandular; without spines; not smooth, or smooth; with elevated features; veined, or not veined; reticulately veined; not tuberculate; not exfoliating, or checking (of cuticle); without cracks, or with cracks (of cuticle); cracking oblique to fruit length; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thin; surface not veined; 1-layered; without balsamic vesicles; without fibers; without reniform canals; solid; coriaceous. Endocarp present; visible; dull; opaque; monochrome; tan; smooth; without adhering pieces of testa; septate; with septa thin (tissue paper-like), flexible; with septa eglandular; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; without wings, or with wing(s) extending into epicarp (section Tetragonolobus); entire. Seed(s) 1–18; length parallel with fruit length; neither overlapping nor touching; in 1 series, or 2 or more series (section Tetragonolobus). Funiculus of 1 length only; triangular, or thick; straight. Aril absent.

Seed: 0.8–5 mm long; 0.7–5 mm wide; 0.3–5 mm thick; not overgrown; not angular, or angular; symmetrical, or asymmetrical; circular, or mitaform, or irregular, or quadrangular, or triangular; terete, or compressed, or quadrangular; with surface smooth; without visible radicle and cotyledon lobes; without hilar sinus; without umbo on seed faces; without medial ridge on each face. Cuticle not exfoliating; not inflated; not wrinkled. Testa present; without pieces of adhering epicarp; not adhering to endocarp; free from endocarp; glossy, or dull; not modified by a bloom; colored; monochrome, or mottled and streaked; with frequent mottles; with frequent streaks; dark brown, or tan (to reddish), or green, or yellow, or purple; with black overlay, or purple overlay; glabrous; smooth, or not smooth; with elevated features; tuberculate; coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; partially concealed, or fully concealed; concealed by funicular remnant; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; punctiform; marginal according to radicle tip, or between cotyledon and radicle lobe; flush; within rim, or within halo; halo darker than testa; rim color darker than testa. Lens discernible; with margins straight, or curved; linear; circular, or elliptic; not in groove of raphe; adjacent to hilum, or confluent with hilum; 0.2–0.4 mm from hilum; mounded; dissimilar color from testa, or similar color as testa; darker than testa; black; not within corona, halo, or rim. Endosperm present; thin, or thick; not pluglike and not resembling tip of radicle; covering entire embryo; adnate to embryo, or testa. Cotyledons smooth; both outer faces convex; both the same thickness; both more or less of equal length; not folded; margin entire 180 degrees from base of radicle; similar at apex; not concealing radicle; entire over radicle; without lobes; with the interface division terminating at base of radicle; without margins recessed; green, or tan, or yellow; inner face flat; glabrous on inner face. Embryonic axis deflexed; oblique to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; linear; deflexed and parallel to cotyledon length; centered between cotyledons; 1/2 to nearly length of cotyledons. Plumule rudimentary; glabrous.

Distribution

North America and extratropical South America, Europe, Russia, extending into Africa and Australia.

New World to Old World; Canada, United States, Mexico, Central America, and South America (southern temperate; Central America: Guatemala); Europe to Mediterranean to Africa to Southwest Asia to Russia to China to Japan to India to Australia to Korea to Macaronesia to Mongolia.

Worldwide crop.

Generic Notes

Polhill (1981k) noted that Lotus and Anthyllis (13.02) seem to be closely related to Hammatolobium (13.17). In our treatment Tetragonolobus G.A. Scopoli is included in Lotus even though the species of section Tetragonolobus have winged fruits and generally larger seeds than species in other sections of Lotus. Lassen (1986) transferred L. roudairei E. Bonnet of North Africa to Acmispon (13.07A) because of its glandular stipules and 5–6 leaflets per leaf. Kramina and Sokoloff (1997) reexamined L. roudairei, and concluded that L. roudairei is not related to New World taxa and should remain in Lotus. They recognized its unique features among Old World Lotus by placing it in the new section Lotus sect. Pseudosimpeteria T.E. Kramina & D.D. Sokoloff. Sokoloff (1999) is now systemtically transferring all New World Lotus species to other genera. Following Isely (1981), he is dividing them into four groups corresponding to those of Isely. He created the new genus Ottleya D.D. Sokoloff to accommodate the species in Isely's fourth group. Given the controversy surrounding the circumscription of Lotus, we have chosen to use the broad circumscription of Polhill.

Tribal Notes

Tribe Loteae

In 1981, Polhill (1981k) accepted much broader generic circumscriptions in tribe Loteae, and only accepted four genera in the tribe: Cytisopsis, Anthyllis (13.02), Hymenocarpus (13.04), and Lotus (13.07). In his most recent classification of Fabaceae (Polhill, 1994a, 1994b), he combined tribes Loteae and Coronilleae and accepted six segregate genera in Loteae, s.s.: Tripodion (13.03), Dorycnopsis (13.05), Dorycnium (13.06), Podolotus J.F. Royle (13.08), Pseudolotus K.H. Rechinger (13.09), and Vermifrux (13.10).