1916] Yates: Histology of Calif ornian Boletaceae 259 



Plants having glandular dots upon the stipe whose surface is, how- 

 ever, not at all reticulate. Pileus convex or nearly plane with age, 

 surface yellow, yellowish-brown, or reddish-brown or streaked. Sur- 

 face smooth and quite viscid. jMargin thin and entire. Tubes adnate 

 or slightly decurrent, short (1.5 to 2.5 mm.), and somewhat depressed 

 in mass. The tubes are dark yellow and unchanging. iMouths circular, 

 large, 1 mm. in diameter. Spores smooth, yellowish-brown, oblong- 

 fusiform, 6 to 9 by 2.5 to 4^. Stipe solid, nearly equal or slightly 

 tapering toward the base, light yellow or reddish-brown, witli glandular 

 dots both above and below the annulus. Context of the pileus pale 

 yellow and unchanging when wounded or sometimes becoming darker 

 with age. Context of the stipe yellowish and unchanging. Pileus 

 5 to 10 cm. broad, and stipe 3 to 6 cm. long and 1 to 2 cm. in diameter. 



The Calif ornian plants differ from the description given above in 

 only a few minor details. The tubes change to a faint tan color when 

 bruised and their mouths are angular. The spores are slightly larger 

 (8 to 10 by 3 to 4.5/x). The stipe is nearly equal, with a context which 

 changes to blue at the base where the plants are usually attacked by 

 insects. The annulus is present at first but soon disappears, apparently 

 deliquescing and leaving a brownish substance on the stipe which 

 sometimes appears reticulate. 



A considerable number of specimens of Boletus lute us have been 

 collected in the vicinity of Muir Woods and Point Reyes, both localities 

 being in Marin County but separated by a distance of about thirty 

 miles. Dried specimens of these plants are filed in the Herbarium of 

 the University of California under Nos. 236 and 243. 



Boletus luteus occurs in this region in cool, moist, mixed woods. 

 The plants grow on the ground under redwood {Sequoia sempervirens) , 

 Douglas fir (Pseudotsuga taxifoUa), Bishop pine {Pinus muricata), 

 ^Madrone {Arbutus Menziesii) , coast live oak {Quercus agrifolia) and 

 tan oak {Pasania densiflora) . The plants appear after the first rains 

 of the season, usually during the latter part of October, remain above 

 ground only a short time and then are not found again until the fol- 

 lowing season. 



No eastern material of this species w^as available, for examination, 

 and consequently I can describe the histology of the Californian plants 

 onlv. 



