Three British rust fungi reported to form aecia on daisy
(Bellis perennis) are compared. A recently discovered species,
possibly
introduced from Australia, is identified as Puccinia distincta.
It is a short-cycled -opsis form lacking uredinia, with aecia
and telia
confined to Bellis and its aeciospores capable of reinfecting
the
same host. This rust is compared with a macrocyclic heteroecious eu-form,
P. obscura, which produces pycnia and aecia on Bellis
and uredinia and telia on Luzula. Puccinia distincta is probably
derived
from and correlated with P. obscura because both species have
the
same aecial host, and because their teliospores are closely similar
in morphology and dimensions. Comparison is extended to P. lagenophorae,
a common rust with aecia and telia on Senecio spp.,
which has been reported to form aecia on Bellis following
inoculation with aeciospores from Senecio. The repeated failure
of our own
reciprocal inoculation experiments using aeciospores from the two
different hosts and differences in teliospore morphology between
P. distincta and P. lagenophorae lead us to conclude
that the current rust epidemic on daisies is caused by P. distincta
which is distinct
from P. lagenophorae.