Symbols evoking Christ's passion very often accompany images of the Madonna and Child. In this case, the grape vine on the wall refers both to the wine of the Eucharist and to what the wine memorializes, the blood shed on the Cross.
The flower in the baby's hand (see detail photograph below) could be either a thistle or a budding rose. The rose is a conventional symbol of the Virgin Mary. Thistles do not usually figure in paintings of this sort, but their thorns could possibly refer to the crown of thorns that the soldiers placed in Jesus' head.
The man in the lower right corner is the donor.
View this image in full resolution.
Read more about images of the Holy Family.
