Flora of North America species comparison

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Lotus

bird's foot trefoil, lotier, lotus, trefoil
Habit 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.

Lotus
Distribution
from USDA
Eurasia; Africa; Atlantic Islands (Azores); Pacific Islands (New Caledonia, Vanuatu); Australia [Introduced in North America; introduced also nearly worldwide]
[BONAP county map]
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.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Herbs annual, hirsute.
→ 2
2. Calyx tubes villous; legumes 12–30 × 1–2 mm.
L. angustissimus
2. Calyx tubes hirsute; legumes 7–10 × 0.7–1.2 mm.
L. subbiflorus
1. Herbs annual or perennial, glabrous, glabrate, or sparsely pilose to strigose.
→ 3
3. Inflorescences 1(or 2)[–4]-flowered.
L. 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.
L. 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.
L. corniculatus
5. Leaflet blade lengths (2.5–)3–5 times widths; flowers 7–10 mm.
L. tenuis
Source FNA vol. 11. Author: Luc Brouillet.
Parent taxa Fabaceae > subfam. Faboideae
Subordinate taxa
L. angustissimus, L. corniculatus, L. krylovii, L. subbiflorus, L. tenuis, L. uliginosus
Name authority Linnaeus: Sp. Pl. 2: 773. (1753): Gen. Pl. ed. 5, 338. (1754)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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