Lotus glaber Mill.
Narrow-leaf or narrow-leaved birdsfoot trefoil; slender trefoil; creeping or prostrate trefoil.
Glabrous to sparsely pubescent perennial. Leaves pentafoliate with two of the leaflets at the petiole base resembling stipules. Leaflets linear to lanceolate. Prostrate growth form with thin stems, erect to decumbent. Plant crown usually well developed. Inflorescences axillary at uppermost stem nodes, umbellate, bearing 8-10 lemon yellow florets, 7-10 mm. The self-sterile plants are cross-pollinated mainly by species of bees. Seed pods of circa 1.5-2 cm change from green to brown as they ripen and become coiled in dehiscence. Seeds rounded or oblong, coloured yellowish-brown to dark brown, sometimes mottled. Plant tap-rooted with extensive lateral root branching especially in upper soil layers. Shallower rooting than birdsfoot trefoil.
Primary distribution in north-west and east Europe, Mediterranean basin, south-west and east Asia; secondarily in Argentina and parts of the USA, mainly western and north-east states, where 8000 ha and 4500 ha, respectively, are sown annually (Blumenthal and McGraw, l999).
Perennial tending towards prostrate growth habit on account of weak stems. Suited to humid-temperate environments. Adapted to poorly-drained, heavy soils and to saline and alkaline soils. Weak to medium seedling emergence with slow establishment ability (see Beuselinck, 1999 for extensive review of the science and technology of Lotus spp., including narrow-leaf trefoil).
Season of growth
Spring to autumn but in areas such as Western Australia where the winters are mild, there are also winter-active lines of the species (R. Snowball, person. comm.).
Less winter hardy than birdsfoot trefoil; however, narrow-leaf trefoil proved to be tolerant of low temperatures and ice-sheeting of water in central-east Argentina (Vigniola et al., 1999).
Intolerant of shade. Long-day plant requiring 12-14 hour daylengths to flower.
Moderately drought tolerant though, because of shallower rooting, less so than birdsfoot trefoil. Can withstand high summer temperatures.
Tolerance of flooding
Tolerates poor soil drainage and swampy conditions. Has colonised the Flooding Pampa grasslands of circa 90 000 km2 in central-east Argentina (Vigniola et al., 1999).
Because of its adaptation to difficult and infertile soils, it can be regarded as a pioneer forage legume. Responds to improved fertility. Soil pH range, 5.5-7.5 (PLANTS database, 2000). Adapted to fine- and medium-textured soils but not coarse-textured soils.
Rhizobial inoculation of seed by effective, specific Rhizobium loti is needed when sowing, especially on land where it has not been grown before.
Ability to spread naturally
Seed shedding from mature plants can aid stand rejuventation. Grazed stands can be managed to allow a seed setting and shedding phase. Is a vigorous coloniser following burning of Paspalum quadrifarium Lam. stands (pajonales) in the Flooding Pampa of central-east Argentina ( Laterra, 1997).
Oversown in humid rangelands in Argentina; used in seed mixtures for pasture and for soil stabilisation in the USA. Sown at 5-8 kg/ha.
Number of seeds per kg
Circa 900 000 to l 000 000.
Seed storage at low temperatures (5 to 7oC) reduced dormancy of hard seed (Arambarri et al., l994).
Ability to compete with weeds
Does not compete well with weeds.
Vigour of growth and growth rhythm
Moderate vigour of growth; regrowth after defoliation also moderate.
Rated as medium (PLANTS database, 2000). In grass-dominant, grazed tall fescue/narrow-leaf trefoil swards on an alkaline hydromorphic soil in the Flooding Pampa area, Argentina, the trefoil fixed 27-42 kg N/ha annually (as assessed by the nitrogenase activity method) while in equivalent tall fescue/white clover swards, white clover fixed 14-59 kg N/ha (Refi and Escuder, 1998).
Poor to medium vigour.
Diploid with chromosome number 2n = 2x = 12 or 24 (Kirkbride, l999). Self-sterile species cross-pollinated mainly by bees.
Largely determined by stage of growth since value falls with plant maturity. Protein-rich.
Acceptable forage for grazing at vegetative stage.
Examples are Boyero from Argentina and Tretana from Montana, USA.
Perennial legume adapted to poorly-drained soils and saline or alkaline soils. Acceptable forage for grazing.
Slow germination and weak seedling development. Not high-yielding. Lacks persistence. Not a forage legume for high fertility soils where it is outperformed by other major forage legumes.
Arrambarri A.M. et al. (1994); Blumenthal M.J. and McGraw R.L. (1999); Kirkbride J.H. jr. (1999); Laterra P. (1997); Plants Database 2000; Refi R.O. and Escuder C.J. (1998); Vigniola O.R. et al. (1999)