Higueras y Olivos en Alemania en el S XIII:
The rare occurrence of hard winters in the MWP seems to have
promoted the cultivation of subtropical trees in the Po valley and
even in the Rhine valley in Germany, where they are not grown
today. This is concluded from several pieces of evidence. The
most distinguished witness is St Albertus Magnus who is known
as a theologian, philosopher and a natural scientist. In his treatise
De vegetabilibus ('On plants') he describes the trees that are
known in the Rhine valley. The list includes pomegranates and
fig trees 'whichare abundant in Cologne and in parts of the Rhine
valley around the town'. The fig trees bore fruits three times a
year, except in cold autumns. Albertus also describes the culti-
vation of olive trees (Jessen, 1867). A chronicler from the same
town reports a freezing of 'vines, fig and olive trees in Italy,
France and Germany' from the bitter frost in January 1234.
Winter air temperature variations in western Europe during the Early and High Middle Ages (AD 750-1300)
C. Pfister, J. Luterbacher, G. Schwarz-Zanetti and M. Wegmann
The Holocene 8, 1998
http://hol.sagepub.com/content/8/5/535.abstractMi Latin no da para mucho, aunque higuera es ficus -i y ficulneus de la higuera, olivo es olea -ae Por si alguien quiere buscar las referencias originales:
De Vegetabilibus:
http://www.botanicus.org/title/b12075516#