522 MacDougal: Symbiosis and Saprophytism 



which extends upwardly a premorse rhizome lo to 15 cm. in 

 length. The thick aerial stem readies a height of i 5 to 25 cm., 

 is sheathed by membranous leaves, and terminated by a strongly 

 developed racemose inflorescence. The leaves and stem are irreg- 

 ularly colored with blotches of reddish, purplish and brownish 

 tints, and appear to be wholly free from chlorophyll. Specimens 

 with rudimentary aerial stems and others in bloom were collected 

 by the writer on Mormon mountain, and on the San Francisco 

 mountain in Arizona in 1891 and 1898, and preserved in alcohol. 

 The results described below are based upon this material. 



The coralloid mvcorhiza 



The mycorhiza of this plant is a dense mass of club-shaped 

 branches arising from the upright underground rhizome, on which 

 the true roots are to be seen as minute papillae. The germination 

 of the seed has not been observ^ed, and it is impossible to say 

 whether the primary roots are developed or not, or at what stage 

 the symbiotic fungus invades the offsets which constitute the coral- 

 loid mass. Reinke figures a young plant, probably of the second 

 year's growth, in which the underground member consists of a 

 coralloid stem only (14). The external anatomy and method of 

 branching need no further description in this species. The rhizome 

 attains a thickness of 4 to 6 mm., with internodes 2 to 4 mm. in 

 length. 



The phloem consists of two or three layers of prosenchymatous 

 cells with yellowish thickened walls and slimy contents, most 

 nearly like companion cells. The phloem forms two crescents with 

 the tips nearly touching with the 3 to 5 xylem bundles lying inter- 

 nally, or the phloem may form a complete ring enclosing the 

 xylem. The xylem consists almost entirely of scalariform vessels 

 and one or two tracheids in which the perforations are oval and 

 elongated obliquely. The central parenchyma is made up of short 

 cylindrical cells often richly loaded with starch. The pericycle is 

 present as one or two layers of cambiform cells, and the endo- 

 derniis forms a sheath of flattened cylindrical elements. External 

 to the stele is a cylinder of cortical tissue 10 to 15 layers in thick- 

 ness composed of ovoid or globoid elements, with large intercel- 

 lular spaces, and containing starch during the resting period. The 



