Lotus
Sp. Pl. 2: 773. 1753.
Herbs, annual or perennial, rarely suffrutescent, unarmed. Stems prostrate or decumbent to ascending or erect, glabrous or pubescent. Leaves alternate, odd-pinnate; stipules present, glandlike; petiolate; leaflets 5, proximal pair stipular in position, distal 3 ± palmate, blade margins entire, surfaces glabrous or pubescent. Inflorescences 1–15-flowered, axillary, umbels or solitary flowers; bracts present, 1–3-foliolate. Flowers papilionaceous; calyx symmetric, bell-shaped or short-cylindric, lobes 5; corolla yellow, usually marked with red, (4–)5–13(–18) mm, keel equaling or longer than symmetrically positioned wings; stamens 10, diadelphous; anthers dorsifixed; ovary sessile or ± stipitate; stigma without collar. Fruits legumes, persistent, exserted from calyx, sessile, straight, body not deflexed, linear to narrowly oblong or cylindric, subterete to quadrate, beak slender, dehiscent, leathery, glabrous. Seeds (5–)10–35, mottled or not, globose to oblong or round-oblong. x = 6.
Distribution
Introduced; Eurasia, Africa, Atlantic Islands (Azores), Pacific Islands (New Caledonia, Vanuatu), Australia, introduced also nearly worldwide.
Discussion
Species ca. 125 (6 in the flora).
Morphological and molecular analyses (G. J. Allan et al. 2003; G. V. Degtjareva et al. 2008) have shown that the Eurasian members of Lotus are distinct from the North American Acmispon and Hosackia. Therefore, Lotus is here defined in its strict sense. Lotus species have been introduced to North America as forage crops and for roadbank stabilization.
Selected References
None.
Lower Taxa
Key
| 1 | Herbs annual, hirsute. | > 2 |
| 2 | Calyx tubes villous; legumes 12–30 × 1–2 mm. | Lotus angustissimus |
| 2 | Calyx tubes hirsute; legumes 7–10 × 0.7–1.2 mm. | Lotus subbiflorus |
| 1 | Herbs annual or perennial, glabrous, glabrate, or sparsely pilose to strigose. | > 3 |
| 3 | Inflorescences 1(or 2)[–4]-flowered. | Lotus krylovii |
| 3 | Inflorescences (1–)3–15-flowered. | > 4 |
| 4 | Inflorescences (4–)5–15-flowered; calyx lobes spreading or recurved in bud; herbs with conspicuous rhizome; stems hollow, glabrate to sparsely pilose. | Lotus uliginosus |
| 4 | Inflorescences (1–)3–8(–10)-flowered; calyx lobes not recurved in bud; herbs taprooted (except rarely rhizomatous in L. corniculatus); stems solid, glabrous, glabrate, or sparsely pilose to strigose. | > 5 |
| 5 | Leaflet blade lengths 1.6–3(–4) times widths; flowers 10–17 mm. | Lotus corniculatus |
| 5 | Leaflet blade lengths (2.5–)3–5 times widths; flowers 7–10 mm. | Lotus tenuis |