what are native hawaiian plants that require a host to live off?

Bromeliads?

Examples of native Hawaiian plants that need a host plant:

Cassytha filiformis is a parasitic vine ( predates Achyranthes splendens var. rotundata f.e. ):
http://www.hear.org/starr/hiplants/images/thumbnails/html/cassytha_filiformis.htm

Four Santalum species, commonly called 'iliahi, are endemic to Hawaii. They are semiparasitic with roots that seek out and tap the root systems of surrounding trees for water and nutrients.
http://en.wikipedia.org/wiki/Santalum

The endangered Bonamia menziesii is a liana native to Hawaii
http://plants.usda.gov/java/profile?symbol=BOME2

Some Peperomoa spec, are epiphytic ( living on trees ) plants:
http://nature.berkeley.edu/~magnacca/pictures/plants/Peperomia%20Kohala.jpg
Viola chamissoniana lives sometimes epiphytic:
http://www.botany.hawaii.edu/faculty/carr/images/vio_cha_fl_side.jpg
http://www.discoverlife.org/mp/20o?search=Violaceae
Another epiphytic plant
Clermontia montis loa robusta:
http://en.wikipedia.org/wiki/Brighamia

Smilax melastomifolia is a vine:
http://nature.berkeley.edu/~magnacca/pictures/plants/Smilax%20melastomifolia%20Kauai1.jpg
Touchardia latifolia ( rarly ) climbing.
http://zipcodezoo.com/Plants/T/Touchardia_latifolia.asp