162 
years and still is at the present time permitting pedestrians to traverse 
this trail at will. Hilo grass infections have been established at all 
points along this trail where the disturbance has been sufficient to 
create an opening large enough to enable it to gain a foothold. Further 
use of this trail will create additional spaces to accommodate Hilo grass 
and assure its establishment in these places. If this trail is closed there 
is still a possibility that it will be overgrown at many points by native 
vegetation. It should not only be closed to pedestrians but steps should 
at once be taken to eradicate it as an opening through the forest by 
the planting of suitable trees and shrubs. 
SUMMARY 
1. In regions of suitable climate, Hawaiian forests have taken direct 
possession of new volcanic areas and held these continuously up to 
the present time. 
2. Oliia trees which constitute tlie predominating element in Hawa- 
iian rain-forests root deeply only in such soils as have good sub- 
terranean drainage. In water-logged soils ohia trees produce super- 
ficial roots only, these being covered by a thin layer of organic 
debris and further protected by the shrubs, ferns^ etc. which nor- 
mally cover the forest floor. 
3. The destruction of the undergrowth in an Hawaiian rain-forest 
is followed by the death of the ohia trees because of the exposure 
and disturbance of their roots. 
4. The native Hawaiian flora did not contain any strong-growing 
grass that built up a perennial grassland which stood opposed to 
the woodland. 
5. Hilo grass is a plant-immigrant which reached these islands less 
than ninety years ago. It is a coarse, strong-growing and freely- 
seeding grass producing a continuous mat over the surface of the 
soil. 
6. With the introduction of Hilo grass the native forest was at once 
confronted by an adversary with which it had never been com- 
pelled to compete and against which it had naturally evolved no 
defense. 
7. Operating from an established base Hilo grass encroaches upon 
the undergrowth in the forest, eliminating the smaller plants by 
overtopping them and preventing the reproduction of the larger 
plants by smothering out their seedlings. 
8. Hilo grass exerts a deleterious influence upon the taller growing 
shrubs and the ohia trees for when it has replaced the low-growing 
ferns and tender herbaceous plants which normally cover the forest 
floor and its roots have permeated the thin layer of soil and organic 
matter which cover the roots of the trees and shrubs these plants 
show signs of distress and soon weaken and die. 
9. Any openings created in our forest will eventually become infested 
with Hilo grass if they remain open a sufficient length of time. 
10. The closing of any opening in the forest by native vegetation will 
take place if the native vegetation can cover the area before Hilo 
grass gains a foothold therein. 
11. When Hilo grass has once become established in an opening in our 
native forest it not only successfully holds the ground occupied 
but makes it a base from which it keeps up a constant and success- 
ful pressure against the surrounding vegetation. 
12. Hilo grass produces adhesive seeds which are designed for dis- 
tribution by adhering to migrating animals. 
13. All trails leading from the lowlands to and through Hawaiian for- 
ests traverse areas already infested with Hilo grass. 
14. All trails through Hawaiian forests are avenues along which Hilo 
grass infection is carried to the interior of our forests. 
