This is a close view taken at home of the underside of a frond and shows developing sporangia and the scaly midrib. Both Polystichum lonchitis and P. munitum were growing in the same vicinity.
This has become a rare and endangered fern in a genus endemic to the Hawaiian Islands. Originally known from all of the major Hawaiian Islands, now it is only found in Glenwood on the Big Island and in a few small populations on Kauai. According to USFWS, the population has declined rapidly (2009), with over 1200 individuals in the 1990's and now only 51-123 individuals in 2009. In my limited perspective, this species is on the brink of extinction.
Endemic to Hawaiian Islands and uncommon. Key features include fleshy stipules (unique to native Hawaiian ferns), pulvini at bases of pinnae, and fused sporangia - synangia. This plant was on a slope below the trail near the junction with the Alakai Swamp trail at around 1204m/3950ft.
This northern fern shows a preference for limestone-influenced areas and differs from its relatives in having fronds distributed along an extended rhizome.