Apothecia and ascospores of Lobaria oregana and Lobaria pulmonaria investigated.

Apothecia of Lobaria oregana and L. pulmonaria emerge in late spring and discharge ascospores throughout the year. Most populations have a few fertile thalli, although the proportion of fertile thalli usually is less than 25 percent. Ascospores fail to germinate in water or on water agar but do germinate on agar containing an adsorbant and either a sugar or the sugar-alcohol ribitol. It is postulated that the ascospores of these species contain an autoinhibitor that must be removed before germination. Widespread ascospore germination in the presence of an adsorbant in Peltigera aphthosa, P. membranacea, and Pseudocyphellaria anthraspis, as well as in Lobaria, suggest that this phenomenon might be widespread in the Peltigerales.