Aluminum in Plants — Moomaw et al. 
The species sampled were about equally di- 
vided among Pteridophyta, Dicotyledoneae, 
and Gramineae, the emphasis on grasses re- 
sulting from the present use of these areas 
mainly for grazing. The plants were identified 
byj. C. Moomaw and E. Y. Hosaka. 
Analytical Procedure 
Chenery’s colorimetric analysis of alumi- 
num using thioglycollic acid as inhibitor for 
iron (Chenery, 1948^) was followed with a 
few modifications. 
The plant samples were prepared for analy- 
sis of aluminum according to the method 
described by Piper (1944). Two grams of 
oven-dried plant material were dry-ashed in a 
Vycor crucible. The ash was put into solution 
with dilute hydrochloric acid and the silica 
was separated and destroyed with hydro- 
fluoric acid. 
A suitable aliquot of the plant digest was 
first pipetted into a 100 ml. beaker and 
diluted to about a 20 ml. volume. To prevent 
the interference of Fe+++, 2 ml. of 1:100 
thioglycollic acid was added to the diluted 
solution to reduce the Fe+++ to Fe++. Next, 
10 ml. of the aluminon mixed reagent was 
added. The pH of this entire mixture was 
adjusted to 4.2 with NH4OH using the Beck- 
man pH meter. Although Chenery’s mixed 
reagent is buffered at pH 4.0, the extreme 
acidity of the plant digest overcomes the buf- 
fering capacity and makes this pH adjustment 
necessary. The intensity of the color of the 
aluminum lake is highly sensitive to pH 
changes; therefore, in order to have repro- 
ducible results, it was necessary to have the 
pH of the plant sample and the standards 
equal. 
The adjusted solution was transferred to 
50 ml. volumetric flasks and heated in a boil- 
ing water bath for 12.5 minutes. The flasks 
were removed and allowed to stand for 10 
minutes, then they were immersed in a cold 
water bath to be cooled to room temperature. 
The cooled solution was diluted to mark and 
mixed. The transmittancy of the solution was 
337 
read on the Klett-Summerson photoelectric 
colorimeter using a green filter. 
RESULTS AND DISCUSSION 
Of the 45 determinations reported in Table 
1, 18 exceed the Chenery criterion of 1000 
p.p.m., thus designating 13 of the 23 species 
as aluminum accumulators for one or more of 
the determinations. Three of the 13 are well 
known from the literature as accumulators: 
Lycodium cermmm, the club moss or wawae'- 
iole; the staghorn fern, Gleichenia linearis; and 
Melastoma malahathricum . The magnitude of 
the aluminum content of Lycopodium species 
is in good agreement with the 0.71 per cent 
found in the extensive review of Hutchinson 
( 1943 ) and others. Staghorn is considered by 
some to be a fair indicator plant for bauxitic 
soils and was given special attention in being 
collected from seven different stations. It 
shows a high aluminum content from all col- 
lections falling in the relatively narrow range 
of from 3500 to 6300 p.p.m. High aluminum 
contents from nonaluminous soil areas, such 
as the Naalehu pahoehoe lava and the Hono- 
kaa soil (Table 2), are taken as evidence that 
it may be an obligate accumulator. Melastoma 
shows a very high content of aluminum, 
especially in the older tissue; this is a condi- 
tion frequently mentioned in the literature, 
although Webb indicates some variability in 
M. poly anthum in New Zealand. 
The highest aluminum content was found 
in Polypodium phymatodes on the Haiku series 
site considered most highly gibbsitic. Webb 
( 1945 ) found all species in Polypodium ex- 
amined by him to be negative but it is not 
known whether P. phymatodes was one of 
these. Stenoloma chinensis, another of the Poly- 
podiaceae, shows evidence of a strong ac- 
cumulation tendency, although it becomes a 
rather low-level accumulator on the Kukaiau 
soil series. 
Pitryogramma and Nephrolepis (Boston fern), 
also in the Polypodiaceae, have a mixed rec- 
ord and indicate a facultative accumulation 
tendency. Two tree ferns, Sadleria cyatheoides 
