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

A single tree <strong>of</strong> Senna siamea (cassod tree, Siamese cassia) was seen in Ngeremlengui State,
Babeldaob. It is invasive in Australia (Cape York Peninsula) and reported <strong>to</strong> be weedy in Tahiti.
Stachytarpheta cayennensis [=S. urticifolia] (louch beluu, blue rat’s tail, dark blue snakeweed) is
very common in <strong>Palau</strong> as it is throughout <strong>the</strong> Pacific. While mostly a pest in open areas, it can
invade in<strong>to</strong> <strong>the</strong> forest, particularly when <strong>the</strong>re has been disturbance. It is a “high risk” species
based on its Australian weed risk assessment score <strong>of</strong> 20. Stachytarpheta jamaicensis (louch
beluu, blue porterweed, light blue snakeweed) is also common and <strong>the</strong> two can hybridize. Both
species are especially prevalent on Angaur and common on Babeldaob.
Some exotic tree species that have been introduced <strong>to</strong> <strong>Palau</strong> include Acacia confusa (ianángi,
yanangi, Formosa koa), Acacia mangium (mangium), Albizia lebbeck (ukall ra ngebard, siristree,
rain tree), Bauhinia acuminata (dwarf white bauhinia), Bauhinia monandra (orchid tree),
Bauhinia purpurea (purple orchid tree), Bauhinia variegata, Ceiba pentandra (kalngebárd,
kerrekar ngebard, kapok), Ficus sp., Ficus benjamina (weeping banyan), Gliricidia sepium
(rechesengel, mo<strong>the</strong>r <strong>of</strong> cacao, quickstick), Muntingia calabura (budo, Panama cherry),
Samanea saman (monkeypod), Senna surattensis (scrambled eggs), Sesbania grandiflora
(katurai, hummingbird tree, scarlet wisteria tree) and Thevetia peruviana (yellow oleander).
These species are known <strong>to</strong> naturalize and can be more or less successful depending on local
conditions. In <strong>Palau</strong>, Acacia mangium is planted in a few locations, but <strong>the</strong> 2002 survey noted
only a few seedlings adjacent <strong>to</strong> <strong>the</strong> small forestry planting in Aimeliik State. Muntingia
calabura is very commonly naturalized along roadsides and in clearings. The rest <strong>of</strong> <strong>the</strong> abovementioned
trees seem <strong>to</strong> reproduce little or not at all in <strong>Palau</strong>, although some <strong>of</strong> <strong>the</strong>m are <strong>of</strong>
continuing concern based on <strong>the</strong>ir weed risk assessments and <strong>the</strong>ir behavior in o<strong>the</strong>r locations.
In addition <strong>to</strong> Arundo donax, Imperata cylindrica, Melinis minutiflora, Panicum maximum
[Megathyrsus maximus, Urochloa maxima] Pennisetum polystachion and Pennisetum setaceum,
discussed in <strong>the</strong> previous section, a number <strong>of</strong> o<strong>the</strong>r introduced grasses are established, including
Bothriochloa bladhii, (desum, blue grass, Australian beardgrass), Cenchrus brownii (burr grass),
Cenchrus echinatus (burr grass); Chloris barbata (swollen fingergrass), Chloris radiata (plushgrass,
radiate fingergrass), Cynodon dactylon (Bermuda grass), Digitaria ciliaris (smooth
crabgrass), Digitaria violascens (sau, smooth crabgrass, violet crabgrass), Eleusine indica
(kelelamalk, keteketarmalk, goosegrass), Panicum repens (<strong>to</strong>rpedo grass), Paspalum conjugatum
(udel ra ngebei, T grass), Paspalum paniculatum (Russell river grass, galmarra grass),
Pennisetum purpureum (bokso, elephant grass, napier grass, merker grass), Sorghum halepense
(Johnson grass), Urochloa [=Brachiaria] mutica (para grass) and Urochloa [=Brachiaria]
subquadripara (green summer grass, tropical signalgrass). Bamboos (esel) (Bambusa spp.) are
also present. Urochloa [=Brachiaria] decumbens (signal grass) was widely seeded for bank
stabilization along <strong>the</strong> route <strong>of</strong> <strong>the</strong> Compact Road.
O<strong>the</strong>r weedy species include Calopogonium mucunoides (calopo), Centrosema pubescens
(centro), Chamaecrista mimosoides (Japanese tea), Chamaecrista nictitans (partridge pea,
Japanese tea senna), Clerodendrum buchananii (butcherechár, red clerodendrum, pagodaflower),
Clerodendrum paniculatum (butcherechár, pagoda flower), Cli<strong>to</strong>ria ternatea (kles,
butterfly pea), Crotalaria micans (crotalaria), Cyperus rotundus (tamanengi, nut grass,
nutsedge), Desmodium <strong>to</strong>rtuosum (Spanish clover), Kyllinga brevifolia (esechesiding, green
kyllinga), Leonurus japonicus (lion’s tail), Macroptilium atropurpureum (siratro), Macroptilium
20