Lucernes
What are they?
This small group of low, many-branched members of the pea family consists of plants that are closely-related and have an interesting association. Lucerne is an introduction to much of Northern Europe as a fodder crop for livestock, while Sickle Medick exists as a native in parts of Northern Europe - including East Anglia. Where these two forms of the same species have met, they have produced hybrids through cross-fertilisation and, since these hybrids are recognisable in their own right, they have been given a name as a'nothosubspecies', which means hybrid subspecies. The three may all be found growing together in Breckland, where both parents occur close to each other. It is possible, over time, that the genes of the new nothosubspecies may stabilise to form a new species, but at present, the crossing of a purple-flowered plant with a yellow-flowered one has created a bizarre assemblage of flowers as they hybrids receive mixed messages from their genes as to what colour the flowers should be!
Where are they found?
These are plants of rough, grassy places along roadsides and field edges.
Identification
All three of these plants can be told by their many-stemmed, subshrub appearance, coupled with the trifoliate leaves and clusters of pea flowers. Telling them apart can be difficult and is best based upon the structure of the ripe seed pods.
Common Lucerne Medicago sativa
Introduced from mainland Europe. Once widely grown as a fodder crop for livestock (when sometimes known as 'alfalfa') but now mostly found as persistent colonies of plants on grassy roadside verges and field edges. Flowers July to September. Plants many-branched, more or less upright to around 90cm in height. The flowers vary in colour from deep bluish-purple to pale blue or even sometimes white. The seed pods curl into spirals as they develop, with ripe seeds being tightly spiralled in two or more complete turns.
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Sand Lucerne Medicago x varia
Introduced from mainland Europe. A hybrid between Common Lucerne and Sand Medick, occurring most commonly around Breckland, but also quite well established along Suffolk's Gipping Valley and in areas to the west of Norwich. Flowers July to September. Plants many-branched, variously upright to spreading, to around 90cm in height. Being a hybrid of a yellow-flowered and a purple-flowered species, the flowers are often an odd mix of the two colours. However, they may also be bizarre shades of copper, turquoise or maroon, or even nearly black. The seed pods curl into spirals as they develop, with ripe seeds being loosely spiralled from 0.5 to 1.5 complete turns.
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Sickle Medick Medicago falcata
A native plant with a stronghold on sandy soil in Breckland and in a few scattered places elsewhere, especially near the coast. Flowers June to August. A rather sprawly perennial plant, growing to around 60cm or so in height, with leaflets typically narrower than those of Common Lucerne. Yellow flowers are carried in tight clusters. The seedheads become curved and sickle-shaped as they develop.
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