Susceptibility of Clarkia to Synchytrium Fulgens

SUMMARY

1.	Fourteen species and subspecies of Clarkia were inoculated with S. fulgens. Thirteen were found to be susceptible to the parasite and in eleven of these viable zoospores were produced.
2.	The evanescent galls and sori on most species of Clarkia are somewhat smaller than the evanescent galls and sori on Oenothera biennis. In almost all species of Clarkia and in O. biennis, the galls and sori tend to be circular, slightly flattened, or upright. On only two species of Clarkia are the galls distinctly flattened. The resting galls and sori on O. biennis compare with the smallest of the resting galls, and sori produced on Clarkia. Except for one species (where the galls are flattened) all resting galls and sori produced on Clarkia and Oenothera biennis tend to be circular, and slightly flattened, or upright.
3.	Slight evidence of a relationship between host haploid chromosome number and susceptibility to the parasite was observed.
4.	A range of gall protrusion from a sunken condition to a highly protruding one was observed.
5.	Abortion of the parasite was found in ten species but mature sporangia were also produced in all of these.