The curious feature about Polyporus rhipidium is its change of 

 color with age. This has never been published, I believe. When 

 fresh it is white, 10 but first turns yellowish and then with age it turns 

 reddish. This seems to be due to some chemical principle, and I know 

 but one other Polyporus with such a character, viz. Polyporus con- 

 fluens. A very similar change takes place in Hydnum septentrionale 

 and related species. 



Berkeley always called the plant Polyporus Rhipidium, though 

 it is found in Saccardo (vol. 6, p. 397) as Favolus Rhipidium, at- 

 tributed to Berkeley. 11 Also in Vol. 9 as Gloeoporus Rhipidium on 

 Spegazzini's authority. It does have some resemblance to a Favolus 

 but none whatever to the character of a "Gloeoporus." In my opinion, 

 it is best classed as a Polyporus for it does not have the pores of 

 a Favolus. 



FORMS. This species departs from the usual order in taking its most 

 luxuriant forms in temperate regions. In the tropics it takes usually a very 

 minute little form rarely over y^ a cm. in diameter. The stipe of this tropical 

 form is not dilated as it usually is in the temperate region form. In addition, 

 the little tropical form grows scattered. In the temperate regions it is imbricate. 

 At first view it would seem to not be the same species, but with the same 

 context, pores, and peculiar color changes and many connecting sizes, I do not 

 question it is the same species. No name has been published for this little 

 tropical form, though it might well have one. It is widespread and at Kew 

 specimens are found from Ohio, North Carolina, Paraguay, Australia, Bonin 

 Island, Ceylon, Brazil, Cuba, Venezuela, Mexico, and New Zealand, and all, I 

 think, correctly named, though all except those from the United States are the 

 small form. In addition, I have collected it in Samoa. The first specimen to 

 reach Europe is found in Persoon's herbarium at Leiden. It was from the 

 West Indies. Persoon labeled it Polyporus pusillus, but never published it. 



POLYPORUS SUBPULVERULENTUS. A rare form in warm regions 

 is pulverulent or rather slightly tomentose. Our figure 260, C and D, is this 

 form (enlarged X6). I have collected it in Florida. 



POLYPORUS VOLVATUS (Fig. 261). A Polyporus that 

 conceals its pores by a thick membrane is a distinct departure from 

 the usual order and well merits being called a "new genus." 12 Since 

 the day that Professor Peck published and illustrated this curious 

 growth it has been a celebrated plant. It grows in our Eastern States 

 "plentifully" in the spruce forests, and Professor Peck states that 

 it usually proceeds from a perforation of the bark caused by a beetle. 



10 Or perhaps yellowish, I do not know. I have only collected the small tropical form, 

 and that, when fresh, is white. Polyporus Rhipidium was first described as "yellowish," and 

 all the freshly dried specimens I have seen of the large form are yellowish. 



11 This change should have been attributed to Cooke, for Berkeley always called it 

 Polyporus, and every specimen in his herbarium is so named. 



12 It was so suggested by Professor Peck shortly after he published it, but Professor 

 Peck has always been conservative in making new genera. Instead of calling it a new genus 

 he called it a "section Cryptoporus." It remained for Shear, of Washington, to discover that 

 it was not a section, but a genus, and thus add his name to it. 



24 



