Comparisons of Basidiospores and Urediniospores of Formae Speciales of Cronartium Quercuum

ABSTRACT

Basidiospores of five formae speciales of Cronartium quercuum can be readily separated into three distinct groups on the basis of color, length-to-width ratios, and size. The Japanese f. sp. densiflorae has globose to subglobose hyaline basidiospores. All four American formae speciales have yellow-orange ellipsoid basidiospores with special forms echinatae and fusiforme having length-to-width ratios of 1.3-1.4, whereas f. spp. virginianae and banksianae have length-to-width ratios of 1.6-1.8. Basidiospores from isolates of three American special forms from widely separated geographic locations had similar shapes and sizes. Urediniospores of the four American formae speciales do not vary in size or ornamentation.

Key Words:

• Cronartium quercuum
• basidiospore
• rust fungi
• formae specials
• special forms