]oS Mycnlogical Bulletin No. 40 [Vol. Ill 



Plcurottis is usually recognized without difficulty among the fleshy, white- 

 spored agarics, because of the eccentric (not quite in the center of the 

 pileus) or lateral stem, or by the pileus being attached at one side in a 

 more or less shelving position, or in some species where the upper side 

 of the pileus lies directly against the wood on which the plant is growing, 

 and is then said to be resupinate. The gills are either decurrent (extend- 

 ing downward) on the stem, or in some species they are rounded or 

 notched at the j miction with the stem. There is no annulus, though some- 

 limes a veil, and the genus resembles both Tricholoma and Clitocybc, ex- 

 cept for the position of the stem on the pileus. In Tricholoma and Cli- 

 tocybc the stem is usually attached at the center, and the majority of the 

 species grow on the ground, while the species of Pleurotus are especially 

 characterized by growing on wood. Some species, at least, appear to grow 

 from the ground, as in Pleurotus petaloides, which is sometimes found 

 growing on buried roots or portions of decaying stumps which no longer 

 shov/ above ground." 



Pleu-ro'-tus ul-ma'-kt-us ; Ei.m Pleu-ro'-tus. — This species is de- 

 scribed as usually growing on the Elm — whence the name — but also oc- 

 curring on other trees. It may be found at wounds where there is decaying 

 wood — but it may occur on the ground as stated in the paragraph below. 

 The mark that distinguishes this large species from the Oyster fungus and 

 other related species is its long stem, usually attached near the center of 

 the cap, and by the gills being rounded or notched at their inner extremity. 

 The pileu'; is convex, the margin incurved, then nearly expanded. It is 

 smooth and white or whitish ; it may be yellowish or brownish in the 

 center. 



Wh.\t the Authors S.av of this Species. — It may add to the interest 

 of this subject if some quotations as to the Elm Pleu-ro'-tus are added. 

 Atkinson savs : "The elm pleurotus has been long known as an edible 

 fungus, and is regarded as an excellent one for food on account of its 

 flavor and because of its large size. It occurs abundantly during the late 

 autumn, and at this season of the year is usually well protected from the 

 attacks of insects. It occurs in the woods, or fields, more frequently on 

 dead trees. On shade trees which have been severely pruned, and are 

 nearly or quite dead, it sometimes appears at the wounds, where limbs 

 have been removed, in great abundance. In some plants the stems are 

 strongly curved because the weight of the cap bore the plant downward. 

 Sometimes when the plant is growing directly on the upper side of a 

 branch or log, the stem may be central." 



Mc'lvriine says: "The historic elms of Boston Common have borne 

 copious 'crop« of this well-known and easily distinguished species from time 

 immemorial. Every fall, about the first of September, if the season is 

 favorabi.'', later if not, copious crops appear decorating the trunks, and 

 branches, sometimes at a height of thirty or forty feet. Growth takes 

 place where branches have broken off or the trees have been wounded 

 from other causes. They occur very generally on elms in the outlying dis- 

 tricts of the city, but rare in the country, seeming to be distinctly urban 

 in their tastes. No damage is apparent from their growth." 



Our Ii.i.ustr.vtion of the Ei.m Pleu-ro'-tits. — The remarkable speci- 

 men shown in Fig. \'M differs much from the conunon type — but they may 

 be representatives of Pleu-ro'-tus ul-ma'-ri-us, as kindly determined for me 

 by Professor Morgan. He remarked concerning them: "Something near 

 Pleurotus ulmirius— the spores of this species, but the form is not typical." 



Excellent figures of the Pleurotus ulmarius are given in Atkinson's 

 Mushrooms Edible and Poisonous (on pp. 102-^). He shows two speci- 

 mens with long, strongly curved stems, as seen from above, from below, 

 and in section, 'i'he other species which he illustrates by half-tones are 

 Pleu-ro'-lus os-tre-a'-tus, Pleu-ro'-tus sap'-i-dus, Pleu-ro'-tus dry-i'-nus 

 Pleu-ro'-tus sul-fu-roi'-des and Pleu-ro'-tus pet-a-loi'-dcs. 



