MacDougal : Symbiosis and Saprophytism 513 



Cephalanthera Oregana Reichenb. (13) 



A number of living specimens of this plant were examined in 

 the field in Washington and Idaho in 1892, and alcoholic material 

 from this region was obtained in 1899. Besides the notes and 

 material thus obtained, the author has had the opportunity of in- 

 specting herbarium material representing the entire known range 

 of the species, from middle California northward into British 

 Columbia, west of the main continental divide. 



The plant consists of an upright subterranean rhizome 5 to 40 

 cm. in length, from the internodes of which arise the adventitious 

 roots. The internodes are provided with short sheathing scales. 

 The aerial stem is slender, waxy white, 20 to 50 cm. long, and 

 bears short sheathing leaves which are wholly devoid of chloro- 

 phyll. The flowers form a dense terminal raceme and perhaps 

 agree with those of other members of the genus in being self-fer- 

 tilizing (Plate 367, Fig. i). 



The seedling has not been observed. The rhizome is peren- 

 nial, and the stumps of two or three old aerial stems may be seen 

 adhering to the most recently formed internodes. Although re- 

 ported from open meadows by some collectors, the author has met 

 it only in the deep humus of coniferous forests. Its deep penetra- 

 tion of the loose substratum, which is generally woven together by 

 the interlacing roots of neighboring trees, makes the collection of 

 the entire plant veiy difficult and as a consequence the greater 

 number of herbarium specimens are lacking the root system, and 

 on none of these has the writer found the mycorhizal rootlets 

 described below. 



The Roots 



The roots are wavy cylindrical organs 1.5 to 3 mm. in diam- 

 eter, and from 5 to 12 cm. in length. One to four arise at each 

 internode of the premorse rhizome, and penetrate the substratum 

 at an angle of forty-five degrees with the horizontal. Mature 

 organs have a yellowish-brown appearance due to the decay of the 

 outer epidermal wall. A many-layered root-cap sheathes the tip 

 for a distance of a millimeter, and shows a fairly normal structure. 

 The epidermal cells are rectangular in surface section, with the 

 radial walls separated to allow a slight outward convexity of the 



