Trifolium alexandrinum L. (E-Medit.?) – A rare and ephemeral alien. Apparently first recorded by an artificial talus slope in Jemappes in 1961. In the past decades probably slightly increasing, mostly in newly sown road verges (for instance at the Kattendijkdok in the port of Antwerpen in 1997 and 1998). Sometimes sown in large amounts (for forage?), for instance in 2003 in Sint-Denijs and Wilskerke (initially erroneously identified as native Trifolium montanum). Occasionally seen on the gravelly banks of river Maas (several records, for instance, in 2011).
Trifolium alexandrinum is a rather characteristic species but mature heads are required for a reliable identification. It is an annual with large cream corollas that are mostly confined to the upper part of the flower head (not all corollas are apparent at the same time). With this particular habit it mostly resembles Trifolium constantinopolitanum and both might have been confused. However, the latter has a calyx that is closed by bilabiate callosity at throat (hence enclosing the fruit). In Trifolium alexandrinum the calyx is open at throat and the fruit is slightly exserted at maturity.
Trifolium alexandrinum, T. constantinopolitanum, T. echinatum, T. squamosum and T. squarrosum are much alike and have been confused in Belgium.
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