BASIDIOMYCETES. 487 



iomycetes are never borne in closed sacs but are borne externally on little 

 stems like miniature clusters of cherries or other fruit. Several devices 

 also occur for ejecting the spores with force which greatly facilitate the 

 matter of distribution. 



One important subdivision of the Basidiomycetes is that known as the 

 plant rusts, the term " rust " referring to the color of the spores in some 

 of the species. The rusts are all parasitic and from an economic point of 

 view occupy a high place among parasitic fungi. Unlike most parasites 

 the rusts have several distinct stages in their life cycles and the different 

 stages often occur on different host plants. Such parasites are known as 

 heteroecious parasites. 



The common grain rust which, although it is not at present known to 

 occur in Bermuda, is likely at any time to be found there, is one of the 

 most important of the plant rusts. The early or spring stage of this rust 

 occurs on the leaves of the barberrj^ bush. The spores produced here 

 cannot reinfect the leaves of the barberry but germinate readily on the 

 leaves and stems of the common grains, both the summer and winter stages 

 being produced on the same host. Two different plants are then made use 

 of in order to enable the fungus to complete its life cycle. It has been 

 repeatedly shown, however, that this fungus can thrive in countries where 

 the barberry is unknown, so that this host is not absolutely necessary to 

 the life of the fungus. Just how the rust is carried over without the 

 presence of this host is a question that has never been veiy satisfactorily 

 answered. 



Nine species of plant rusts have been collected in Bennuda, occurring 

 on about twelve different hosts, some of which are of no particular economic 

 importance. The rust of Sorghum and that of cultivated peaches are 

 likely to be of some economic importance. Additional species may be 

 expected to appear in Bermuda as the work of agriculture and horticulture 

 becomes more extended in the islands. While only nine species have been 

 collected, it is not unlikely that more occur but have escaped notice. 



Among these is a cedar rust known as Gymnosporangium hermudi- 

 anum, a species which is related to our own cedar-apple rust, affecting red 

 cedar and cultivated and wild apples, and causing great losses where apples 

 and cedars are cultivated in close proximity. The cedar rust occurring in 

 Bermuda apparently causes little or no damage. 



Another group which is usually included with the lower Basidiomycetes 

 are the smuts, so-called because of the black mass of spores which are 

 formed usually associated with the flowers or fruit of the host. The only 

 species observed in Bermuda is the common corn-smut, a species which 

 causes great losses wherever maize is extensively cultivated. This is one 

 of the parasitic fungi, however, which can be easily controlled by the appli- 

 cation of the principles of scientific agriculture. 



The Basidiomycetes contain those forms known as puffballs, toad- 

 stools and mushrooms, many of which are commonly used as articles of 

 food. While some edible species were collected in Bennuda, they were 

 found only sparingly and whether these occur in sufficient quantity to be of 

 practical use, it is difficult to say; although they are likely to be abundant 

 during periods of excessive rainfall. 



Among the puffballs the only species collected was one of the earth- 

 stars, Geaster saccatus. The earthstars differ from the other puffballs in 



