12 



SILVA OF NORTH AMERICA. 



CONIFERS. 



This fungus seldom appears on the trunks, although it grows on 

 their cut surfaces and is common on the ground under Pinus 

 Strobus, being probably parasitic on its roots. It is a large species 

 of a corky or spongy substance, at first covered with a yellow 

 down but soon becoming dark brown. It is not improbable that 

 it is a, native of North America, and has been introduced into 

 Europe. There are also a large number of Hymenomycetes which 

 attack Pines in this country, but at present little is known defi- 

 nitely of their pathological effects. 



A number of interesting rust-fungi produce discolorations and 

 deformities of the leaves of Pines in the United States, and, in some 

 cases, the peculiar distortion known as witches' brooms, although 

 this deformity is more common on Spruce-trees than on Pines. The 

 determination of the Rusts which infest conifers is difficult, owing 

 to the fact that the greater part of them are secidia, or cluster-cups, 

 which resemble one another closely, but, according to recent writers, 

 are genetically connected with teleutosporic fungi of quite different 

 species. The rusts of Pines, with few exceptions, belong to the 

 genus Peridermium which, like other aecidia, consist of orange or 

 rust-colored spores arranged in chains contained within an en- 

 velope composed of colorless cells. The old species, Peridermium 

 Pini, Le'veille', was supposed to have two forms, one producing 

 cups on the leaves and the other cups or irregular disks on the 

 trunks and branches. It has been shown that the forms on bark 

 are connected with species of Cronartium, but the leaf Peridermium 

 of European Pines is now separated into several species connected 

 with different species of Coleosporium which grow on different 

 Composite, as Senecio, Tussilago, Inula, and on Euphrasia and 

 other plants. Few experiments have been made with artificial 

 cultures of the North American Periderrnia, and the determina- 

 tion of our species must still be regarded as provisional. Perider- 

 mium Strobi, common in Europe on Pinus Strobus introduced from 

 North America, is not known to occur in this country, nor has 

 Cronartium ribicolum, Dietrich, with which it is associated, been in- 

 troduced here. Of North American corticolous forms may be men- 

 tioned Peridermium Harknessii, Moore, which forms nodes covered 

 with confluent masses of secidia on Pinus ponderosa, Pinus radiata, 

 Pinus Sabiniana, and Pinus contorta, and Peridermium Cerebrum, 

 Peck, on Pinus rigida. Of North American acicolous forms of Pe- 

 ridermium the most common is perhaps identical with Peridermium 

 oblongisporum, Fuckel. This is not uncommon on Pinus rigida in 

 early summer, but the teleutosporic form with which it is said to 

 be united in Europe, Coleosporium Senecionis, Persoon, is certainly 

 very rare here, although it has been noticed on Senecio vulgaris 

 near Providence, Rhode Island. Besides the Rusts belonging to 

 the genus Peridermium, Coleosporium Pini, Galloway (Jour. Myc. 

 vii. 44. — Bot. Gazette, xxii. 433), attacks the leaves of Pinus Vir- 



giniana in the middle states, causing bands of yellow discolorations 

 and a premature shedding of the leaves. Unlike other Rusts of 

 Pine-trees, this species is a teleutosporic and not an aecidial form. 

 The Rusts which are often found in abundance on cones of vari- 

 ous Pine-trees, especially in the southern and western states, need 

 further study. 



A number of fungi of the order Hysteriaceae are found on Pine- 

 trees, most of them being species occurring on the bark without 

 causing special disease so far as is now known. Lophodermium 

 Pinastri, Chevallier, found on Pinus contorta, Pinus palustris, Pinus 

 rigida, Pinus Strobus, and probably on other species, which appears 

 to the naked eye as small narrow black spots on the leaves, kills 

 them and causes them to fall prematurely. Hypoderma brachy- 

 sporum, Rostrup, a. species closely related to the last, produces a 

 similar disease of Pinus Strobus in Europe, but is not known in this 

 country. There are several other ascomycetous fungal parasites 

 in the United States. Cenangium ferruginosum, Fries, occurs on 

 the branches of Pinus radiata, Pinus ponderosa, Pinus Sabiniana, 

 and Pinus sylvestris in this country. Under the name of Cenan- 

 gium Abietis, Persoon, F. Schwartz (Die Erkrankung der Kiefern 

 durch Cenangium Abietis) has given a full account of the epidemic 

 caused by this fungus in Germany, the same disease having been 

 previously observed by other botanists in that country and in 

 Sweden. The species attacked were Pinus sylvestris, Pinus Lam- 

 bertiana, Pinus montana, and Pinus rigida. In America no special 

 epidemic has been observed, and most botanists have regarded the 

 fungus as a saprophyte rather than a true parasite, although it ap- 

 pears to be capable at least of assuming at times a truly parasitic 

 growth. Phacidium crustaceum, Berkeley & Curtis, which should 

 probably be referred to the older Phacidium Pini, Albertini & 

 Schweinitz, is very common on the branches of Pinus Strobus, which 

 it covers with small depressed silvery gray pustules. Chilonectria 

 cucurbitula, Saccardo, a polysporic form, is abundant on the smaller 

 branches of Pinus Strobus, which it covers with small clusters of 

 deep red perithecia. The exact relation of this common fungus to 

 the true Nectria cucurbitida, Fries, has not been fully determined. 

 The latter species is recognized in Europe as a cause of a marked 

 disease, the mycelium, making its way into the branches of Pinus 

 sylvestris through wounds, especially those caused by certain in- 

 sects. Caliciopsis Pinea, Peck, which is found on the bark of Pinus 

 Strobus, and Polyporus volvatus, Peck, which grows on the bark of 

 Pinus rigida, are peculiar to these trees, which, however, do not 

 appear to be injured by them. In southern Europe the tumors 

 sometimes found on the branches of Pinus Halepensis are supposed 

 to be due to the growth of bacteria which cause similar tumors on 

 Olive-trees. 



42 Inst. 585, t. 355, 356. 



