Even so,
the atoll received sufficient moisture to maintain vegetation on
almost all portions which are continuously above high tide.
The character of
this vegetation is a result of human activity and the bio-physical factors such
as soil and underlying rock, waterlevel,
and tolerances
of individual species.
It has not been possible to make a careful study of all of these factors.
ever,
How-
observations and suggested correlations may be of some value.
As would be expected on a group of small islets composed almost exclusively
of coral and coralline sand with many fragments of mollusc shells, the vegetation
is a strand vegetation with Scaevola frutescens and Messerschmidia argentea the
most frequent shrubs or small trees.
Where the soil is somewhat richer in
organic matter Pisonia grandis, Guettarda speciosa and,
subcordata become more frequent.
Coconuts occur in regular rows, having been
planted by the Japanese or Marshallese Islanders.
reach 60-70 feet in height,
on some islets, Cordia
Beneath the trees, which may
there are hundreds of sprouted nuts as well as seed-
lings and small plants of the more common shrubs and plants.
Vines are an
important adjunct to the vegetation along the margins of the tall shrub
thickets or forest.
Broadly speaking,
the vegetation may be described as composed of three
relatively distinct "zones".
The first of these is low, with the plants and
shrubs not, or barely exceeding, one meter in height.
The factor which seems to
determine the presence of this type of vegetation is shallow sand or isolated
ARL ae ene
sand spits separated from the main water lens of the islet.
It is here that
Triumfetta procumbens and Ipomoea pes-caprae, both trailing or creeping vines,
reach their maximum development.
Low,
stunted or dwarfed Scaevola also occurs
with patches of Lepturus forming open grass-mats on the higher or deeper-sandy
spots,
The "tall shrub" type of vegetation, consisting of shrubs to five or six
meters tall,
occupies
the major part of each islet.
Scaevola frutescens and
Messerschmidia argentea compose the greater portion of this shrub.
Ipomoea tuba
is generally found at the "contact" of this vegetation with the low strand
vegetation.
Somewhat richer goils support Guettarda speciosa, Cordia subcordata,
and Terminalia littoralis.
Rocky-sandy spits, even though separated from the main water-lens, are
occupied by this type of vegetation, but with Pemphis acidula as the nearly
16