9 
Vegetation and flora of Vostok Island 
’oy C. E. Long 
The flora of Vostok Island consists of two species of vascular 
plants, Boorhavia repens L. and Plsonla grandis L® (Fosters, 1937)• 
Collections of these"species were made in 1935 by J♦ Anderson and 
in 1965 by 0. E. Long. These collections are summarised below. The 
sheets are filed at the B. P. Bishop Museum and the University of 
Hawaii. 
Kyct aginaceae 
Boerhavia repens L® 
•Anderson s.n. (BISH) as Boerhavia. diffusa ; Long 3191, 3202, 
3203, 3204, 3208 (UK). 
Pisonia grandis E® Br. 
Anderson s®n. (BISH;; Long 3192 v Jj 4* 
The island remains much as Anderson reported with a dense growth 
of Pisonia trees to approximately 20 m® -irgh. Towares tnc miadle 01 ^nc 
island are randonaclearings with thick layers > v to ®o5 *- i »; decayed 
leaves and wood. On the sandy edges of these clearings several Boerhavia 
plants were observed® Several excavations were made in the open', areas 
and under the canopy. Underlying 'one humus was a pnosphatic harcipan 
which was very friable in the top .layers® The high branches of the 
Pisonia were -used by the (greater frrigatebird as nesting sites. Some of 
the upper branches were bare in the vicinity of the nest sires due per¬ 
haps to the activities of these birds. On the north and east sides of 
the island were open coral send and rubble^ with B oerhavia. in vigorous 
masses. This site was used by nesting bluefaced boobies (Sula dactylatr gj . 
This strip of low vegetation varied from 3 to 20 m® in widen® An intensive 
search of the island failed to reveal otner plant species particularly 
the Portulaca reported by Bryan (1942) • The Polynesian rat was common 
within the forest canopy, xt may be tiiat the rorruisca is eaten oy .his 
species.\4t the southwest end there is an outcrop of consolidated beach- 
rock. It seems highly probable that both of the native species were in¬ 
troduced by birds as the seeefs of both are sticky and thus easily trans¬ 
ported® Ho evidence of Pisonia seedlings was found but numerous sprouts 
from fallen trunks and exposed roots were seen. Binoculars wex*e used . to 
scan the upper branches but no fruits were observed. Along the west side 
areas of eroded soil and newly deposited sand were observed.^ This evidence 
together with the clearing in the center of the island probably indicates 
high wave action prior to the visit of the Pacific Project party in Juno 
1965 . Sea water and heavy rains probably seep through the porous central 
area which is at a lower elevation than the beach crests and innox slopes. 
The area5 beneath the Pisonia canopy are devoid of vegetation with tne 
'* exception of crusts of bluegrcen algae which cover the soils surface, 
rotting trunks and coralline boulders. Ho thicx recent guano deposit 
were observed on the soil surface under the canopy. The humus depths 
vary under the canopy suggesting that a lagoon may have existed afc oue 
time. The deepest litter and huvx:: layers are found in the central area. 
Small coconut crabs were found but chore ’./as no evidence Oi Cocos o.. 
the island. The absence of 
sue. 
... c scr. 
Leu turn. 3 and Portulaca is 
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