May 1, 1925 
Taxonomic Studies oj Fvsarium 
837 
4. Sclerotia: Plectenchymatic struc¬ 
tures, general appearance 
similar to perithecia of Gib- 
berella, but with uniform 
structure throughout. Glo¬ 
bose or rugose, single or in 
cauliflowerlike clusters (fig. 1, 
Gi). Color, blue in sections 
Roseum, Gibbosum, Lateri- 
tium, Discolor, Elegans, and 
Martiella; brownish to dark 
brown in Arthrosporiella (F. 
diversisporum Sherb.), Gib¬ 
bosum, and some species of 
section Discolor. 
II. Color characters 
1. Color of conidia: Brownish white 
to golden yellow in section 
Martiella; brownish white to 
pale orange in section Elegans, 
Discolor, Gibbosum, and Ar¬ 
throsporiella; orange in sec¬ 
tion Roseum Lateritium, Eu- 
pionnotes and Arachonites. 
The color of conidia is suffi¬ 
ciently constant to be a reli¬ 
able character for some 
groups. 
2. Color of aerial mycelium: White, 
rose to yellow and blue, 
mostly representing a diffused 
color of the stroma. Changes 
in color of mycelium due to 
the reaction of the sub¬ 
stratum is substantially the 
same as that discussed under 
color of stroma. 
3. Color of stroma: Brownish white, 
carmine, yellow, and blue. 
The acid modification is espe¬ 
cially well developed on ster¬ 
ilized rice and may aid in the 
identification of Fusarium 
groups. This acid modifica¬ 
tion differs in some sections 
for it is golden yellow in most 
of the species in section Dis¬ 
color, Saubinetii, Roseum, 
Sporotrichiella, and in some 
of Gibbosum; rose to vine red 
in many species of section 
Elegans; and rose to brown 
color, with a tendency toward 
diffusing into rice, in section 
Martiella. The basic color 
modification is mostly blue or 
violet. In general, all of these 
fungi produce on rice an acid 
color modification that may 
change gradually with age 
into an alkaline modification. 
This color change can be 
produced at once by the 
addition of sufficient alkali 
to a well-developed culture of 
the fungus on rice. Other 
characteristic colors produced 
on sterilized potato tubers 
are carmine red by species 
of section Discolor, Roseum, 
Sporotrichiella, and some of 
Gibbosum, and citric or sul¬ 
phuric yellow in Neesiola 
subsection of Discolor. These 
colors are of the basic modi¬ 
fication and consequently are 
not turned blue by the addi¬ 
tion of alkali. The carmine 
red turns yellow with an ad¬ 
dition of acid. No color con¬ 
trast is observed in sections 
such as Eupionnotes, Arach¬ 
nites, and Ventricosum. The 
stroma and aerial mycelium 
of these fungi have the color 
shades of their conidia. The 
color of sclerotia and sclerotial 
stroma is blue in some and 
brown in other groups, as dis¬ 
cussed under sclerotia. 
III. Minor characters 
1. Hyphae with swollen cells: Not 
true chlamydospores (fig. 1 Y) 
as in F. flocciferum Cda. and 
F. tricinctum (Cda.) Sacc. 
2. Aerial mycelium: Loose, dense, 
jellylike, cottony, radiate, 
zonate. 
3. Immersed mycelium : Slimy or 
leathery sheet (stroma), that 
may or may not have a 
plectenchymic base. Section 
Eupionnotes. 
4. Coremialike aggregations of hyphae . 
Aggregations of anastomosed 
hyphae as in Eupionnotes and 
Ventricosum. True coremia 
so far were not observed. 
5. Aromatic odor: Somewhat similar 
to lilac odor, produced by a 
number of species of section 
Elegans such as F. oxysporum 
Schlecht., F. hyper oxysporum 
Wr., F. zonatum (Sherb. s. 
var.) Wr., F. vasinfectum Atk., 
and F. cubense Erw. F. Sm. 
The last three species have 
the strongest odor, especially 
when grown on rice. 
IV. Abnormal characters 
1. Spore: Exceptional size, irregular¬ 
ities in shape of conidia, 
swollen cells in germinating 
spores (fig. 1, W) and con¬ 
stricted cells in dry conidia 
(fig. 1, X). These abnormal 
characters, although frequent¬ 
ly present, are not taken into 
consideration for taxonomic 
purposes and have been more 
fully discussed elsewhere (/). 
