Methods
This checklist was compiled from published and unpublished lists of plant names, then each plant family was studied intensively in the course of preparing A Tropical Garden Flora. The checklist is being updated as new specimens and new taxonomic information become available.
I. Data collection
The initial compilation of names was made between 1984 and 1987 from the living collection inventories of the Harold L. Lyon Arboretum (unpublished circa 1980) and the Honolulu Botanical Gardens (Ayers & Kariel 1984). To this compilation were added all plant names from In Gardens of Hawaii (Neal 1965) and additional names transcribed from labels on herbarium specimen housed in the Bishop Museum. This first pass resulted in a list comprising an estimated 9,000 names of species and infraspecific taxa (e.g., subspecies, varieties, formae).
In 1988 the inventories for two more major botanical gardens in the Islands were obtained and all names from those inventories were added to the project database (Pacific Tropical Botanical Garden staff 1988, Waimea Arboretum Foundation 1988). By December 1993, the checklist had grown to more than 12,400 scientific and cultivar names for ferns, gymnosperms, and flowering plants cultivated in Hawai‘i, including about 9,900 accepted names and 2,500 synonyms classified in more than 280 families and 2,500 genera.
A second pass through the living collections inventories for the same four major botanical gardens added many names for new plants that had been introduced up to 1995 (Honolulu Botanical Gardens 1994–95, Lorence et al. 1995, Lyon Arboretum 1994–95, Waimea Arboretum Foundation 1994). From 1996 onward no major lists of new names have been added to this checklist, although new species have been added as they are documented and verified. One source of names currently unavailable due to privacy considerations is the invoices accompanying shipments of plants introduced to the Hawaiian Islands from outside the USA. It is unknown how many new species of plants arrive in Hawai‘i annually via horticultural introductions for commercial nurseries and landscaping. Because of this unavailability, this checklist will never be totally complete or up-to-date but will always lag behind new plant introductions.
II. Data verification
Verification of the information presented in the checklist takes several forms: 1) verification that the scientific names are published in accordance with the rules of botanical nomenclature; 2) verification of the identity of the plants themselves; and 3) verification that the scientific names are being correctly applied to those plants. This is best accomplished through the collection of voucher specimens for the herbarium, and was the working method followed throughout this book project.
Herbarium voucher specimens constitute a permanent record of the existence, identity, and name of each plant species present in Hawai‘i. George Staples and Derral herbst, the principal authors of A Tropical Garden Flora, undertook the initial taxonomic research involved in the verification process, assisted by Research Assistants Clyde Imada and Katie Anderson. A higher level of verification was sought wherever taxonomic specialists were known for particular plant families or genera. These specialists were asked to examine voucher specimens and provide expert identifications for them. We are deeply indebted to the more than 220 taxonomic specialists who assisted us in this manner; the scientific foundation for this checklist is greatly strengthened because they were willing to share their taxonomic knowledge and experience with us. The fact that this checklist is based on herbarium voucher specimens rigorously verified by the best taxonomic expertise available puts it in a league by itself.
When using the checklist Search function, any verified scientific name appears with a green check mark beside it. This signifies that there is a voucher specimen, usually deposited in the Bishop Museum Herbarium Pacificum (BISH), that has been verified with the same name used in the checklist. Many names pulled up by the Search function are unconfirmed and this indicates how much more collecting and taxonomic verification work remains to be done to document every plant species cultivated in the Hawaiian Islands.
Whether or not the plant name has a documented voucher specimen, the scientific names have been checked to verify that they are published according to the rules of botanical nomenclature and, in the case of cultivar names, the rules of horticultural nomenclature.
