20 Plant Invasion on Lava Flows. 



branches were composed of extremely rough aa and supported no 

 vegetation, with the exception of a few Metrosideros on the contact 

 edges with the older flows. 



The 1907 flow was visited at a point a short distance above 

 Puu o Keokeo, which is about two and one-half miles above Puu 

 Ohia. At this point the flow is entirely pahoehoe, very shiny black 

 and fresh looking. Plants were just beginning to be established 

 in a few of the cracks, the following being observed: 



Polypodia in pellucid ion Klf., var. Vaccinium penduliflorum Gaud. 



The folded form. Cyatliodcs Tameiameiae Cham. 



Cypcrus sp. Raillardia sp. 



All of these plants are indigenous and constitute the prevail- 

 ing flora at this elevation. The naturalized flora is not 3 r et estab- 

 lished to any considerable extent on this portion of Mauna Loa. 



The 1907 flow was visited later at the place where it crosses 

 the Government road on the Kona side. At this point it is aa and 

 supports no vegetation except an occasional lichen or moss, appar- 

 ent only on minute examination. 



The flow of 1823 was visited where it crosses the Kau Desert. 

 It is pahoehoe, but unfortunately much of the vegetation had 

 been eaten by goats just before my visit. In a deep crack which 

 crosses the flow, practically all the species of plants which occur 

 in the surrounding region were observed. The following plants 

 were observed in the surface cracks: 



Cibotinm sp. Metrosideros poly niorpha Gaud., 



Nephrolepis exalt a la ( L, . ) Schott . var . 



Psilotum nudum (L,.) Griesb. Solan am nigrum L,. 



Another recent but unrecorded aa flow was visited above 

 Kapapala near the old Kahuku trail. With the exception of a 

 few lichens, no vegetation was observed upon it. 



From these observations of the plant invasion on the flows of 

 known date the following summary might be obtained: 



1. A few lower cryptogams, followed by ferns and phanero- 

 gams first become established on the pahoehoe. 



