By Trish Moore, Star-Bulletin
Antone Parraga said he got two flat tires when he drove
over this Prosopis juliflora, a much thornier version of the
kiawe tree, on the sand dunes in west Kauai.

An unwelcome cousin
pops up on the coasts
of Kauai, Niihau

The kiawe cousin has huge thorns
up to three inches long

By Trish Moore

Star-Bulletin

MANA, Kauai -- A cousin to the kiawe tree is causing a thorny problem among the sand dunes of Mana in west Kauai and along the southern coast of Niihau.

Kauai resident Antone Parraga discovered the weed Sunday when two of his steel-belted radial tires went flat after he drove over one of the scraggly branches that creep along the sand.

Prosopis juliflora has beans and flowers similar to the common kiawe tree, but it grows more like a bush and has sharp thorns up to three inches long. It was first found in the islands at the nearby Pacific Missile Range Facility in 1978.

The only other place in the state the weed has been found is on Oahu at Sand Island, said Guy Nagai, noxious weed specialist with the state Department of Agriculture.

The weed was mostly eradicated from the missile range facility three years ago, Nagai said.

The new infestation is just east of the county landfill, along a beach access route to a surf break.

Prosopis has a shallow root system and seems to grow in the dry coastal sandy areas between the high water mark and normal soil. But it has the potential to cross-pollinate with other species, which means some form of it could adapt to inland habitats, said Nagai, who spotted about seven plants on a recent trip to Niihau.