Report to the Republic of Palau: 2008 update on Invasive Plant ...

Timonius timon (Liberal) is widespread on Angaur and Peleliu. Individual trees and small stands
were found on a number <strong>of</strong> <strong>the</strong> Rock Islands. It was probably introduced <strong>to</strong> Angaur and Peleliu
during or shortly after World War II and has since spread <strong>to</strong> <strong>the</strong> Rock Islands. Several individual
trees and an apparently reproducing infestation were located on Babeldaob. Single trees
(possibly planted) were previously observed on Kayangel and Ngerkebesang. It is an invader <strong>of</strong>
open, disturbed areas. As time goes by, it seems <strong>to</strong> be over<strong>to</strong>pped and replaced by native
species, and it seems <strong>to</strong> be less prevalent on Angaur and Peleliu than formerly as <strong>the</strong>se forests
have become more mature. Its presence in <strong>the</strong> Rock Islands indicates that it is spreading <strong>to</strong> <strong>the</strong>
north and, unless checked, will probably eventually reach Koror and Babeldaob where it would
probably be an invader in open and disturbed areas and potentially hybridize with endemic
species <strong>of</strong> Timonius.
Tradescantia spathacea (kobesos, oyster plant, boat plant, boat lily, Moses in a boat) and T.
zebrina (wandering jew) are planted as ornamentals in <strong>Palau</strong> but have escaped in several
instances. Several examples <strong>of</strong> Tradescantia spathacea invading <strong>the</strong> forest unders<strong>to</strong>ry were seen
on Peleliu. A fairly large patch <strong>of</strong> naturalized Tradescantia zebrina can be seen in Ngiwal State,
Babeldaob, as well as on Angaur. There is a small naturalized patch on Kayangel. These plants
are commonly spread through <strong>the</strong> dumping <strong>of</strong> garden cuttings.
Turnera ulmifolia (yellow alder, sage rose) is widely planted as an ornamental. Naturalization
was noted at a number <strong>of</strong> locations. The seed is reported <strong>to</strong> be carried by ants (Staples et al.,
2000) and <strong>the</strong> species is widely naturalized in <strong>the</strong> tropics. A related species, Turnera subulata
(white alder), was also noted in cultivation. This species is somewhat weedy in Malaysia and
has a weed risk assessment score <strong>of</strong> 10, “high risk”.
Invasive species <strong>of</strong> limited extent
The following species are limited in extent or have recently become established. Some <strong>of</strong> <strong>the</strong>m
are only in limited cultivation and could be eradicated at minimal cost. O<strong>the</strong>rs may be
candidates for control action or should just be moni<strong>to</strong>red for possible future action, if necessary.
See <strong>the</strong> recommendations section for species-specific recommendations.
Acacia [=Vachellia] farnesiana (Elling<strong>to</strong>n curse, klu, sweet acacia) was seen at one location in
cultivation in Airai State, Babeldaob, during <strong>the</strong> 2002 survey. This thorny shrub is a pest in Fiji,
French Polynesia, New Caledonia, Solomon Islands and Vanuatu and has a “high risk” weed risk
assessment score <strong>of</strong> 14.
Alternan<strong>the</strong>ra brasiliana (Brazilian joyweed, Joseph’s coat) is planted as an ornamental and
occasional escapes were seen. It is invasive in Queensland, Australia.
Antigonon lep<strong>to</strong>pus (dilngau, chain <strong>of</strong> love), a climbing vine <strong>of</strong>ten planted as an ornamental, is a
widespread pest on Guam. Although this species has been subject <strong>to</strong> control action, several
examples, mostly in cultivation, were seen in Koror. It is a “high risk” and difficult <strong>to</strong> remove
species with a weed risk assessment score <strong>of</strong> 19.
A few examples <strong>of</strong> Asparagus densiflorus (asparagus fern, sprengeri fern) were seen, all in
cultivation (<strong>of</strong>ten in hanging baskets). Asparagus densiflorus has recently been found <strong>to</strong> be
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