Sand Lucerne is a hybrid of two other subspecies, which also back-cross and are partly fertile. There is therefore confusion with this plant. Because none of the above had yellow flowers, the photographs might not actually be of Sand Lucerne. The only way to tell for certain is to compare the seeds pods, those of Sand Lucerne are spiralled with between ½ and 1½ turns, whereas those of Lucerne are spiralled in 2 to 3 and even 4 complete turns. Alas, the seed pods were not out when the photographs were taken. But it was growing on old sand dunes near the sea.
Slight resemblance to : Bush Vetch which is also bushy with blue to purple flowers in similar heads, but the leaves are very different, being pinnate.
Superficial resemblance to : Goat's Rue which is also shrubby, but taller, and with pinnate leaves rather than trefoil leaves and the flowers of Goat's Rue are in a loose spire and usually lilac or white whilst those of Lucerne have purplish flowers with spiral pods.
No relation to :
Sandworts nor to Sand Leek, Sand Pansy,
Sand Spurrey or
Sand Crocus [plants with similar names].
There are three sub-species of Medicago sativa:
Going by the colours alone, the samples from the beach west of Llandudno must be those of Sand Lucerne, since green is not in the spectrum of colours supposedly exhibited by Lucerne. As must the white example from Stavely near Chesterfield.
- Lucerne (Medicago sativa ssp. sative) which is by far the most common. Fruits slightly curved to spiral with 2 - 3 turns. Flowers mauve to violet. 10-20 seeds. Introduced and naturalised.
Sand Lucerne (Medicago sativa nothossp. varia) which is rather rare RR. Fruits curved or spiralled with 0.5 - 1.5 turns. Flowers yellow or white, or purple or green or blackish. 3-8 seeds. The hybrid between Lucerne and Sickle Medick, but back-crosses and is partly fertile.
Sickle Medick (Medicago sativa ssp. falcata) which is also rather rare RR. Fruits nearly straight to a semi-circle. Flowers yellow. 2-5 seeds. Native in East Anglia, introduced and naturalised elsewhere.