Holly leaves are a quintessential part of Christmas, whether they are hung up as decorations in boughs and wreaths, as a seasonal garnish on top of Christmas puddings or on the front of Christmas cards. Now new research published in the Botanical Journal of the Linnean Society has connected a combination of herbivore activity and epigenetics to the prickliness of holly leaves.
A number of studies have supported the idea that increased plant prickliness is a response to herbivory by large browsing animals such as deer and goats. Holly (Ilex aquifolium) is a small evergreen tree found throughout Europe and North Africa. The leaves of holly can either be smooth or with a variable number of tough spines along the margins. The production of these spiny leaves is a defence mechanism against herbivores. Holly trees sometimes only have one leaf type, but typically they have both prickly and non-prickly leaves on the same plant (known as heterophylly) with the proportion of the two types depending on plant age, size and recent browsing history.
“The ability of an organism to change its characteristics in response to environmental variations is known as phenotypic plasticity and it is a key driving factor in the evolution of a species” said Dr Carlos Herrera from the National Research Council of Spain (CSIC) in Seville. Continue reading