Conservation of the Critically Endangered Hawaiian species Phyllostegia electra (Lamiaceae)

Seana Walsh, Dustin Wolkis, and Ken Wood, National Tropical Botanical Garden

Phyllostegia electra (Lamiaceae) is endemic to the mesic and wet forests of Kaua’i. It is listed as Critically Endangered on the IUCN Red List of Threatened Species and is a focal species for achieving conservation objectives outlined in the Hawai’i Strategy for Plant Conservation. With less than 50 known wild individuals among 15 subpopulations, P. electra is also a focal species of the University of Hawai’i’s Plant Extinction Prevention Program. It is not, however, protected by the Endangered Species Act.

A grant from the Mohamed bin Zayed Species Conservation Fund is supporting NTBG staff to: 1) make conservation collections from wild populations, 2) conduct a genetic diversity study in collaboration with Chicago Botanic Garden (CBG), 3) outplant into protected and managed habitat, and 4) investigate optimal seed storage methods.

Eighteen remote field work trips have been undertaken since March 2017 to secure conservation collections and obtain leaf material for the genetic diversity study. Genetic marker (microsatellites) development was recently completed and silica-dried leaf material sent to CBG for DNA extraction. Since June 2017, 215 individuals have been outplanted into Kalalau Exclosure and NTBG Gardens and Preserves. Preliminary results of our investigation into optimal seed storage indicate that seeds do not tolerate exposure to liquid nitrogen without prior desiccation. We also found that germination was significantly higher in the 42% eRH frozen treatment compared to the 30% eRH frozen treatment. This work is directly contributing to the conservation of this rare taxon and we are using this multi-faceted project model in our approach to conserving other rare plant taxa as well.