PHYTOGEOGRAPHY OF MANOA VALLEY, HAWAIIAN ISLANDS 577 
the head of the valley over beautiful waterfalls. There is also a series 
of springs along the foot of the cliffs at the head of the valley, which 
contribute their waters to the stream. Other springs, notably those 
on the grounds of the Kawaiahao Seminary and Punahou Academy, 
occur on the valley floor. 
The ten contributory branches of the stream are freshet in char- 
acter and very intermittent in their flow. The stream proper is never 
wholly dry. After the rare protracted droughts it becomes very low, 
and its branches cease to flow. The upper course of the stream lies 
in the middle of the valley. The lower course has been strongly 
deflected against the east foothill, presumably by the outpourings of 
lava and other volcanic material from the craters in the west foothill. 
The stream leaves the valley at the extreme eastern side, hugging the 
base of the east foothill, where it has carved a small narrow canyon 
through the thick beds of ancient flow lava. 
The stream is marked throughout its course by vegetation char- 
acteristic of streamways and swampy places. Due to the general 
utilization of the stream waters for irrigation, the swampy areas and 
hi kalo {taro patches), adjacent to the stream itself are here considered 
as a part of this ecologic zone. The vegetation of the streamway is 
nowhere sharply, differentiated from that of the valley floor. In 
numerous instances the species that grow most luxuriantly along the 
stream are also forms most abundant on the valley floor. 
From the ecologic standpoint the stream is at present a factor of 
minor importance in determining the phytogeography of Manoa. 
It undoubtedly had a more prominent role in early times, before the 
valley floor was overrun by introduced vegetation. One of the 
influences of the stream is as an agent for the dissemination of seeds. 
Frequently the seeds of montane species are carried to lower levels, 
where they occasionally establish themselves. It is extremely sig- 
nificant, however, that there has been no general seaward migration 
of montane species via the stream ; in general the forests have retreated 
up stream. 
7. PLANTS ABUNDANT ALONG OR CHIEFLY CHARACTERISTIC OF 
THE MANOA STREAM AND ITS TRIBUTARIES, INCLUDING 
ADJACENT SWAMPS AND TARO-PATCHES 
Group I. Algae 
Anabaena confervoides Reinsch. 
" variabilis Kuetz. 
Aphanothece repens A. Br. 
Bulbochaeta spp. 
Caloihrix fusca Bornet. 
