The Parasitism of Orthocarpus Purpurascbns. 259 



do it only after you know your plants in the field and in the 

 laboratory, know them macroscopically and microscopically. 

 Study them from the standpoint of the systematist and the 

 physiologist; then you will be more nearly prepared to attempt 

 the problems of variation and distribution, problems which tax 

 every bit of knowledge and every power of thought. 



A great deal of desultory work has been done on the lichens 

 of North America in general, but so far as the writer is aware the 

 only regions in the United States of which we have exact, defin- 

 ite knowledge (relatively speaking) of the lichen flora are New 

 England, Minnesota, Iowa, Northern Illinois, Southern Califor- 

 nia, and the Santa Cruz peninsula, California. This means that 

 an immense lot of investigation awaits local students almost 

 everywhere; one might safely count on ten years' work almost 

 anywhere west of the Missouri. No matter where you live there 

 is not a winding canyon, not a group of old forest trees, not a 

 precipitous crag by the waterside, not an insignificant ledge of 

 rock outcropping in the hill pastures, but which has an inter- 

 esting story to tell of its lichen flora, a story that will amply re- 

 pay the careful perusal of any keen-eyed, thoughtful lover of 

 nature. 



THE PARASITISM OF ORTHOCARPUS PURPURASCEXS 



BENTH. 

 By W. A. Cannon. 



When in March, 1908, the root systems of some of the desert 

 annuals were being studied an examination of the roots of 

 Orthocarpus revealed the presence of numerous small enlarge- 

 ments of the finer roots of the plant which proved to be haustoria. 

 Further examination showed that the plant was united by these 

 haustoria to the roots of several of the neighboring annuals, 

 and, hence, that Orthocarpus was a parasite, probably of the 

 same nature as Castilleja, its near relative 



Orthocarpus is a low annual, mostly less than 15 cm. in 

 height, which comes after the winter rains, and is dependant on 



