Research project P 14416 Function of Complex Haustorial Systems in Mistletoes Gerhard GLATZEL 26.6.2000
Some mistletoe species, in particular in the Loranthaceae, develop a complex haustorial system of epicortical roots
with secondary haustoria and shoot systems. Many functional aspects, aside from the obvious mechanical fixation
and vegetative propagation, have not been studied in any detail. By source sink manipulation, i.e. severing of
epicortical roots and host branches as well as partial removal of mistletoe and host foliage and subsequent study of
the parasite`s growth respons and mineral nutrient partitioning we expect to be able to answer the following
questions. (1) is the secondary haustorial system a response to loss of functioning of the primary system, (2) is the
secondary haustorial system influenced by host species and environmental factors, (3) is there a feedback of source
capacity (cross section of the supporting host branch) on the haustorial system. The mistletoe in this project will be
Scurulla parasitica growing on Rhododendron arboreum and other hosts in Nepal. Nepal was chosen because of its
very steep environmental gradients, the availability of field helpers (tree climbers) at very modest rates and, last
not least, the interest of Mr. Mohan Devkota, lecturer at Amrit Science College, Kathmandu, who is experienced in
field work in Nepal and has a good knowledge of the native flora. A better understanding of the biology of
mistletoes is of interest to conservation, because mistletoes are absolutely dependent on their endangered tree hosts.
In cases where mistletoes have become pest in orchard or tree plantations, control could be improved by a better
understanding of the parasite`s biology. As a spin off the mistletoe flora of the Annapurna Conservation Area will
be documented.