Lecture 1 — 3 — Rise of Mycotrophy 



hazarded the suggestion that Monotropa secures nutriment from 

 the surrounding humus. Drude, in 1873, conformed to tradition 

 by stating that Monotropa starts life as a parasite but later, he asserted, 

 the plant becomes a saprophyte on soil humus, a fungus being present 

 in its tissues. The true nature of Monotropa was first made clear 

 by Kamienski in 1881, who carefully described the structure of its 

 mycorrhiza and indicated that the plant is supplied with nutriment 

 by a fungus which derives its materials from the soil humus. His 

 papers (for there were two) have long since become forgotten history 

 but they were considered important in their day. 



Nutrition of Orchids: — Orchids, like Monotropas, also proved 

 exceptional in their root structures. Indeed, many orchids have no 

 roots ! In place of roots they have branched stems that form coral- 

 structures that anchor the plant in the rich humus soil in which it 

 grows. It was in 1842 that Schleiden described what were later 

 recognized as fungal hyphae in Neottia (for Neottia has been as 

 necessary to orchid students as Drosophila to geneticists), but 

 Schleiden confessed he did not know what the "tubes" were which 

 he had observed in the rhizomes. Unless, he said, they were like the 

 ones which Gottsche had found in liverworts. Five years later 

 Reissek identified true fungal hyphae in rhizomes of many orchids 

 but he oddly concluded that these hyphae developed from starch 

 grains. But Schacht in 1854 showed that the starch in reality was 

 utilized by the fungus, which forms a weft of hyphae about the 

 starch grains. Just how the starch was digested (by the process we now 

 call phagocytosis) was described by Prillieux in an excellent paper 

 that appeared in 1856. He found in orchid cortical cells (needless to 

 say, of Neottia), a yellowish-brown matter, and he noted that these 

 cells retained their nuceli which were of great size and provided with 

 two nucleoli. The matter seemed to be nitrogenous and was woven 

 about with septate hyphae but as phagocytosis proceeded the matter 

 dwindled ; and Prillieux concluded that this matter served as nutri- 

 ment for the orchid. He observed, too, that cells filled with granular 

 matter at flowering time gradually lost the matter as anthesis ad- 

 vanced. The granules were apparently absorbed and they probably 

 nourished the orchid. But Prillieux's work was little regarded and 

 later papers by other authors were farther from the truth. Thus 

 Reinke in 1873 suggested that this yellowish matter which he called 

 slime, acted as a pumping organ, swelling up as water was taken in 



