Kelley — 26 — Mycotrophy 



The genus Cephalotaxus is virtually uninvestigated, for aside from 

 notes by Reinke and von Tubeuf, there is only an observation by 

 Prat (1926) that plants of this genus were abundantly mycorrhizal 

 in the Arboretum at Angiers in France. Torreya has exactly the same 

 record ; and there is nothing whatever on record of the American 

 Torreya which lingers in the Appalachicola hills of Florida. Taxus, 

 being of more familiar presence, is better known as to its mycorrhizae : 

 the older generation of mycorrhizal students noted it and in more re- 

 cent days several have described it, particularly Prat (1926, 1934), 

 who has made rather thorough studies of, first, the European T. bac- 

 cata, and, second, the Canadian T. canadensis. The mycorrhizae in 

 Taxus appear to be endotrophic mamelons or pearl-necklace beaded 

 rootlets, and phagocytosis occurs in them. In his later paper Prat con- 

 cludes that there is not a true mutualism but that the tree is a parasite 

 on its parasite! Kle6ka and Vukolov (1935) record for T. baccata 

 endotrophic mycorrhizae comparable to those of Ginkgo. 



The genus Pherosphaera, sometimes doubtfully included in the 

 Taxaceae, was studied by Saxton (1930), who found both species 

 provided with nodules, but the Tasmanian species produced nodules 

 more freely. 



Mycorrhizae in Pinaceae: — Pines, orchids and heaths, — these 

 are the mycorrhizal plants par excellence ! Frank brought mycor- 

 rhizal study to the fore by his studies on pines and much of recent 

 research has been concerned with these important economic trees. The 

 first genus in the family for our consideration is Juniperus, the com- 

 mon juniper which, like the Yew, is of familiar presence. Its mycor- 

 rhizae are endotrophic (vide KleCka and Vukolov, 1935) and neck- 

 lace-beaded but as Janse (1897) observed: "Les mamelons sont en- 

 core plus allonges et plus rares que chez le Cupressus. Au demeurant 

 ils leur resemblent beaucoup". Sarauw (1903) observed that in this 

 species (the common juniper) an endotrophic mycorrhiza exists in con- 

 junction with an Hartig net, which he says is the only case of the sort 

 known, except that in Cedrus Deodara there is an Hartig net without 

 a mantle. In recent days the mycorrhizae of /. communis have been 

 monographed by Lihnell (1939) in an extended and well-illustrated 

 paper. The American species of Juniperus are very little studied : 

 McDouGALL and Jacobs (1927) state that /. monosperma is endo- 

 trophically mycorrhizal in the Central Rocky Mountains ; Henry 

 (1936) states that no mycorrhizae occur in /. sibirica and in /. utahen- 

 sis. J. sibirica Burgsd. is the same as /. communis L. var. montana Ait., 

 and /. communis is well known to be mycorrhizal in Europe. 



