Lysimachia iniki is assessed as Critically Endangered under criterion B as it has an EOO of less than 100 km² (4 km²), an AOO of less than 10 km² (4 km²), is restricted to only one location and is experiencing an ongoing decline in in EOO (i), AOO (ii), area, extent and/or quality of habitat (iii), number of subpopulations (iv), and number of mature individuals (v).

Lysimachia iniki is narrowly endemic to one extremely wet vertical cliff area in the Upper Wailua watershed on the island of Kauaʻi in the Hawaiian Islands. This species is found between 610 and 1,000 m elevation.

The taxon is extremely rare and grows in vertical cliff habitats making accurate population estimates difficult. In the 2015 IUCN Red List Assessment for this species, botanists estimated a total known population of 40 individuals in one subpopulation, however this was based on binocular counts from the base of the cliff due to the inaccessibility of the plants. New drone technology has been deployed to assist in population counts and is providing a much clearer picture of species distribution and abundance, as well as in-depth data on species associations (Nyberg et al. 2023). Drone surveys from 2019-2023 have uncovered one new subpopulation and counted ca. 325 mature individuals.

The two existing subpopulations of Lysimachia iniki are located along one section of the mixed shrubland sedgeland along the weeping cliffs of Waiʻaleʻale. This area is among the wettest places on earth, receiving up to 1,000 cm of precipitation annually. Its habitat is exclusively on vertical cliffs that reach up to 1,000 m in height, and are completely inaccessible on foot. Associated native plant species include Cyanea asarifolia, Cyrtandra wawarae, Dubautia sp., Kadua sp., Metrosideros polymorpha, as well as a range of ferns and mosses.

The major threats to this taxon include direct competition by invasive non-native plant species and habitat degradation and predation by non-native animals. In addition, the taxon is highly threatened by landslides, which are frequent in the area.

There are no known uses for this species.

The taxon is on the U.S. Endangered Species List, and also on the State of Hawaiʻi Endangered Species List. Ex situ cultivation and seed storage is ongoing. The National Tropical Botanical Garden has and continues to undertake ex situ conservation work through the growing of plants in the Living Collections and Horticulture Nursery and storing seed in the Seed Bank. New drone collecting methods have made intentional collection possible, and boosted ex situ collections both in the nursery and in seed storage. Currently 332 seeds are being held at NTBG, and ca. 25 individuals are being grown at NTBG nursery for return to habitat in 2024.