H# i - i T II i I I I i 1 1 u ml i fT 
C.R. Long 
1964 
forming a continuous band. Tho Sosuvium is found on the‘southeast end alone* 
The Cassytha is found on Ileliotronium and on Suriana hut is not as conspi¬ 
cuous on Mo uU Upou as on Coolc island nor does the parasitized vegetation 
seem in as had a condition* The Scaevola on Motu Upou seems to have smaller 
flowers than that observed previously. I think that this particular group 
oi plants is epuite distinct irom the ones observed and collected on Palmyra* 
Perhaps the water availability is a key factor* The vegetation resembles 
the south end of Cook Island although there is less Tribulus and Boerhaavia * 
jjQorhaavia does occur on Motu Upou in dense patches on the inner parts of the 
island. In the Heliotrondum — Lepturus association on the west side of Motu Upou 
the action of the nesting shearwaters has had the tendency to mound the soil 
with the plants on top of the mound. ‘ 
June 16, 1964 — L. Hubei*, F. Sibley and I were forded to the peninsula of 
Christmas Island which was northeast of Motu Upou. ¥e followed the road east 
through the Cocos groves and past the airfield to the northeast point. He 
then continued south along the shore road along the Bay of Wrecks and along 
the southeast shore to the point where the shore line turns south. I fell 
behind the others at the northeast point while collecting - later overtaking 
them and passing as I continued southeast along the road. It was a hot day 
and the plants wilted fast. In order that I could botanize on the return trip 
I left at dusk and rode along the Bay of Wrecks after dark sleeping at the 
roadside from 8 pm. until 3:30 when a shower awakened me. I waited for first 
light and retraced the previous days route collecting along the way. The long 
southeast peninsula-is interesting and I hope that we will have the oppor¬ 
tunity to do a more thorough job in that area. The large land area of Christmas 
Island makes for a variety of plant associations which were observed along 
the southeast shore. On the rochy, uplifted sites along the road occur 
Scaevola — Lepturus and/or Heliotropium associations. The latter species 
usually occurs in sandy soils where the beach has "blown out" or in wind 
Blown, sand pockets in the coral rubble.' Along the shore occur stunted or 
half dead plants of Messerschmidtia . The prevailing wind is from the east 
and this would seem to be a factor. In the depressed inner part of the island 
where the wind does not have full desiccating effect the Messerschmidtia grows 
quite high and has much less dead wood per tree. Large parts of the inner * 
portion of the island are filled with Scaevola , open areas of solid Lepturus, 
and Leoturus — Sida . The low "lakes" or inner lagoons have rings of vegetation 
with Sesuvium on the inner side and forming a solid mat on the floor of the 
depression. On the higher, dry sides one finds seedlings of Portulaca, and ■ 
then a bare area with a few Lepturus seedlings followed by more solid clumps 
further back from the edge of the Sesuvium mat. Several score of yards from 
the edge the Lepturus and Scaevola are mixed and then one finds a solid 
Scaevola stand. The following associations were observed: 
1. Scaevola - Lepturus - Messerschmidtia 
2. Messerschmidtia — Heliotropium — Portulaca 
3. Lepturus — Sida — Scaevola 
4. Lepturus — Portulaca 
5# Digitaria — Fimbristylis . (Digitaria covering large areas to the 
east of the road east and south of the airfield.) 
6. Sesuvium - Messerschmidtia - Lepturus 
7. Lepturus - Suriana - Messerschmidtia - Portulaca • 
8. Suriana — Heliotropium . 
Tbe controls on the spread of any one speoies or species association are 
many: wind proteotion or not; soil base — from fine coral sand to coarse 
