12 
false diagnosis may result by confusing the species with Poria bor- 
bonica or P. alb o cine t a. These species always produce in the wood 
a highly characteristic and permanent red stain and may be present 
in wood without the development of fruiting bodies. Both species 
have been collected on the wood of Hevea, but so far only as 
saprophytes. 
Poria graphica is another common species producing a red stain 
in the wood, but it has not been collected on the wood of Hevea. 
The species is abundant, however, on associate trees. The three species 
last named may also sometimes produce reddish mycelial strands. 
Since the development of this structure in P. vincta is not always 
Bvident, other moans may sometimes be necessary to detect the pres- 
ence of the fungus. The presence of the fructification, which has a 
different structure and color change from the other three species, 
together with the character of this rot and the usual absence of 
the red stain in the wood are to be considered in doubtful cases. The 
decay of P. vincta in the early stages is firm and slightly yellowish. 
In advanced stages it is soft and wet when in the ground, but white, 
light, and friable when dry. 
The fructifications are entirely resupinate, as is the case in all 
members of the genus. The initial development is the formation of 
a thin yellowish white plate, with a whitish and slightly fimbriate 
margin. The pores as they first develop as a thin layer on the plate 
are yellowish white, and later pink. On maturity the pores be- 
come reddish brown and may or may not develop a slight cinereous 
or gray color. The pores are small, scarcely visible with the naked 
eye. and the layer they form over the bark is about 1 to 2 milli- 
meters in thickn: 
The pathogenicity of the fungus in the American Tropics and its 
probable economic importance must be left to future investigation. 
The species is common on jungle stumps and is found throughout 
tropical America. Since it was found decaying the wood of living 
roots of an unknown jungle tree and was collected on living roots 
of Hevea it may be expected to occur in plantations where original 
forest material is left in the area. 
Poria hypdbrunnea, a closely related species found and described 
by Petch on Hevea in Ceylon, is reputed to be the cause of con- 
siderable root-rot. Poria riypolaterima, a species closely related in 
some respects, is reported as causing one of the commonest root 
diseases of tea in Ceylon. The species occurs in Africa and probably 
also in the American Tropics. 
GANODERMA ROOT-ROT 
The disease caused by Ganoderma amazonense n. sp. is widely 
distributed in the Amazon Valley and occasions considerable root- 
rot in Hevea. It was first found decaying the roots of Spondia 
lutea, but in the main it appears to be more intimately associated 
with Hevea. It was found on the roots of this host at eight dif- 
ferent stations. The causal organism described as Ganoderma 
amazonense does not agree with any known species of the genus. 
(See p. 84.) 
The white spongy decay is without any special diagnostic char- 
acter. At first firm, the decay becomes soft and spongy, and in 
