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excavated to determine root development in 
species planted in these soils. Tap roots of these 
trees penetrated to what appeared to be the 
bottom of the planting hole before turning up- 
ward toward the surface. 
Two individual plants and a thicket growth 
of R. foment os a were excavated in the Koolau 
soil near Hanahanapuni Crater. Tap roots of 
the two individual plants penetrated 9 inches 
downward before turning diagonally for 1 or 
2 inches. Small plants of M. malabathricum 
nearby, like the R. tomentosa, had tap roots 
which penetrated from 8 to 10 inches. 
The main tap root of the R. tomentosa thicket 
penetrated 24 inches downward in the Koolau 
soil without turning, even though water from 
the soil filled the hole at a depth of 1 ft, placing 
it well below the water table at the time of 
sampling. One lateral root of this thicket was 
observed from which numerous stems had 
arisen. This was the only observation of this 
type in the plants excavated. It is possible that 
this "root” could have been a stem buried by 
road construction since the thicket was located 
dose to a forest preserve road. The Koolau soil 
in this area has a grey surface 8 to 10 inches in 
thickness with a reddish-brown, yellow-mottled 
layer below. 
A 5 -ft M. malabathricum plant about 20 ft 
from the R. tomentosa thicket was also ex- 
cavated and the tap root was traced to a depth 
of 18 inches where water rapidly filled the 
trench. 
A series of R. tomentosa plants in the Halii 
Fig. 2. Melastoma malabathricum excavated in the 
Kapaa soil series, Wailua Game Refuge. Note the 
shallow lateral roots and the small tap root. 
PACIFIC SCIENCE, Vol. XVII, October 1963 
Fig. 3. Plants of Rhodomyrtus tomentosa from the 
Halii soil series on Kilohana Crater, Kauai. The lateral 
root of the larger plant was 11 ft long. 
soil series were excavated on the northern slopes 
of Kilohana Crater. These plants had extremely 
shallow root systems with tap roots turning 
laterally at about a 4-inch depth and with lateral 
roots almost at the soil surface (Fig. 3). R. to- 
mentosa shrubs in this area were easily pulled 
up without digging, and tracing of lateral roots 
was accomplished by pulling. Excavation of such 
roots was difficult because of long overlapping 
lateral roots of surrounding plants. One 40-inch 
plant had a lateral root which arose from the 
tap root about 2 inches below the soil surface 
and which was traced at depths of 1 inch or less 
for 11 ft. 
No evidence of root injury was found in 
R. tomentosa plants grown in pots except for 
an unusual blunting of root tips in the Halii 
soil. This blunting is best described as a curving 
and thickening of the root tip which then re- 
sembled a miniature chicken’s head. Some black- 
ened tips were also found in the Halii soil, but 
since the concretionary iron-rich surface of the 
Halii soil was used in these pots it is doubtful 
that these root abnormalities were due to A1 
injury. 
The only evidence for thicket formation of 
R. tomentosa in this pot study was the presence 
of a number of buds on the tap root just below 
the soil surface. Young shoots were observed 
arising from these buds and often 6 to 10 young 
shoots were growing simultaneously on one 
plant. The number of shoots arising from buds 
increased with time. Bud numbers of single 
plants ranged from 5 to 30. 
