136. Lotus Linnaeus, Sp. Pl. 2: 773. 1753.
百脉根属 bai mai gen shu
Bonjeanea Reichenbach; Dorycnium Miller; Miediega Bubani; Mullaghera Bubani; Scandalida Adanson; Tetragonolobus Scopoli.
Herbs, annual or perennial, subshrubs, or rarely shrubs. Leaves pinnate or palmate, usually sessile, 3-9-foliolate; stipules absent, or reduced to small dark glands; leaflets sessile or on very short petiolules, most species with 5 leaflets, 3 crowded at apex of leaf rachis, 2 at base; basal pair similar to apical ones or often differing in shape and stipulelike. Inflorescence an axillary, pedunculate, 1- to many-flowered umbel; peduncle with a sterile bract usually represented by a conspicuous leaf with 1-3(-5) leaflets; flower-subtending bracts reduced to small dark glands (rarely with a herbaceous blade) or absent; bracteoles usually absent, when rarely present then glandular. Calyx campanulate or trumpet-shaped; teeth 5, subequal or distal longer, sometimes connate into 2 lips. Corolla yellow (often turning green in herbarium), pink, violet, brown, or white. Vexillary stamen free. Ovules numerous or several; style entire [or with a small toothlike appendage]; stigma terminal. Legume linear to ovoid, straight or incurved, terete or flattened, longitudinally dehiscent [indehiscent in 1 species outside China]. Seeds subglobose or lenticular, smooth, rarely verrucose.
About 125 species: temperate and subtropical Africa, Asia, N Atlantic islands, Australia, Europe, W Pacific islands; introduced in the Americas, New Zealand, and some other islands; eight species (one to three introduced) in China.
Sectional subdivisions are given after Kramina and Sokoloff (Byull. Moskovsk. Obshch. Isp. Prir., Otd. Biol. 108(5): 59-63. 2003) and Sokoloff (Byull. Moskovsk. Obshch. Isp. Prir., Otd. Biol. 108(3): 35-48. 2003); these are based on morphology and chromosome numbers. Molecular phylogenetic data (Degtjareva et al., Canad. J. Bot. 84: 813-830. 2006; and Wulfenia 15: 35-49. 2008) are not always consistent with this classification (e.g., Lotus sect. Heinekenia is paraphyletic), but further research is needed to see if putatively monophyletic groups can be morphologically characterized.
Species nos. 4-7 represent the Lotus corniculatus complex, a polyploid complex including both diploid and tetraploid taxa, which are not clearly distinguishable by morphological characters. Introduced in North and South America, Australia, and New Zealand, the taxa are native to E and N Africa, Asia, and Europe.
Lotus pedunculatus Cavanilles (Icon. Descr. 2: 52. 1793; L. uliginosus Schkuhr) is a widespread species of swamps, wet meadows, and other wetlands native to N Africa, SW Asia, and Europe, and introduced in S Africa, Australia, North and South America, and the Pacific islands. In view of this broad non-native distribution, it may also be introduced in China, although no confirmed records are known to the present authors. A short description is provided here. Herbs, perennial, 30-100 cm, glabrescent or sparsely pilose, with underground off-shoots. Stem erect or ascending, subglabrous to villous, hollow. Leaflets obovate, 8-25 × 3-15 mm, often glaucous abaxially, with prominent midrib. Heads (1-)6-12(-18)-flowered; peduncle long. Calyx teeth ca. as long as tube, spreading in bud, pilose. Corolla yellow, 10-18 mm. Legume 15-35 × 1.8-2.5 mm. Seeds olive or yellowish to light brown, usually unspotted, small, ovoid, 1-1.2 mm.
