Pairs of leaves on petioles formed along a rhizome rooted in
sand. Leaves from 3 - 8 mm wide, obovate, not narrowing at base, thin and
hairy; margin spinulose. Petiole 3 - 15 mm long. Male and female flowers are
produced at each leaf node. Branching leads to intertwined plants in a
meadow or runners colonizing new substrate.
Leaf blade thin and flaccid out of water; fine hairs on both
sides of leaf make leaf feel rough. Spines on margin visible with
magnification. Ripening fruit often conspicuous on rhizome.
Forms dense meadows in sand rich in organic matter. Found at
depths from 0.5 - 35 m. Often coated with epiphytes.
Hawai‘i: O‘ahu, Hawai‘i.
Mechanism of Introduction:
Worldwide: Subtropical to tropical
Pacific, Indian, Atlantic Ocean, Caribbean.
Halophila decipiens was discovered October, 2000 near
the Kahala Mandarin Hotel and several additional populations have since been
located. If it is found to out-compete the native
then it may pose a threat to that species due to its great reproductive
capacity. Research is underway to determine what impact this species may
have on the native seagrass and associated communities.