Although primarily a saprotrophic fungus involved in the post @-@ fire breakdown of duff and coniferous roots , Geopyxis carbonaria has been shown to be capable of forming ectomycorrhizae with Norway spruce ( Picea abies ) . It had been demonstrated earlier in laboratory experiments that the fungus has a biotrophic interaction with lodgepole pine ( Pinus contorta ) . The hyphae of G. carbonaria were able to infect the cortex of the tree seedling , but did not penetrate the endodermis . These traits suggest that the fungus is a moderate pathogen , with limited ability to cause reductions in seed germination . Additionally , the fungus produces the enzyme polyphenol oxidase , and can break down the complex organic polymer lignin — features characteristic of saprotrophic fungi . The formation of a rudimentary Hartig net , a characteristic of mycorrhizal fungi , indicated that G. carbonaria might be capable of forming mutualistic relationships under the right conditions . Vrålstad and colleagues suggest that its below @-@ ground association with spruce roots protects it from physical damage in the event of a fire , and the extensive fruitbody production after a fire may reflect  a successful fungal escape from a dying host where the fungus no longer can maintain its biotrophic association  . Large fruitings of the fungus are often associated with damage to the host tree , such as that which occurs with burning . A field study conducted in Norway demonstrated that fruit bodies were more likely to be found in areas that were heavily burned , compared to locations with light to moderate burning where the trees remained viable , or in clearcut areas . Fruiting was much denser in spruce forests — with up to 700 – 1000 fruitbodies per square meter — than in pine forests , where fruitbodies were sporadic . Fruitbodies grew by the millions in the year following the Yellowstone fires of 1988 . Gold dollar  The gold dollar or gold one @-@ dollar piece was a coin struck as a regular issue by the United States Bureau of the Mint from 1849 to 1889 . The coin had three types over its lifetime , all designed by Mint Chief Engraver James B. Longacre . The Type 1 issue had the smallest diameter of any United States coin ever minted . A gold dollar had been proposed several times in the 1830s and 1840s , but was not initially adopted . Congress was finally galvanized into action by the increased supply of bullion caused by the California gold rush , and in 1849 authorized a gold dollar . In its early years , silver coins were being hoarded or exported , and the gold dollar found a ready place in commerce . Silver again circulated after Congress in 1853 required that new coins of that metal be made lighter , and the gold dollar became a rarity in commerce even before federal coins vanished from circulation because of the economic disruption caused by the American Civil War . Gold did not again circulate in most of the nation until 1879 ; once it did , the gold dollar did not regain its place . In its final years , it was struck in small numbers , causing speculation by hoarders . It was also in demand to be mounted in jewelry . The regular issue gold dollar was last struck in 1889 ; the following year , Congress ended the series . fill in the blank  : Although primarily a saprotrophic fungus __________________ in the post @-@ fire breakdown of duff and coniferous roots , Geopyxis carbonaria has been shown to be capable of forming ectomycorrhizae with Norway spruce ( Picea abies ) . 
Output:  involved