SUMMARY AND BRIEF ANALYSIS OF THE FLORA

(Updated from the introductory text to the Manual of Flowering Plants of Hawai‘i (1990) under the same title.)

The Hawaiian Islands have long been known for their remarkable ecological diversity and the high level of endemism of their fauna and flora. The Hawaiian flora is also disharmonic. For example, only 3 native orchids and a single native palm genus occur here, and native gymnosperms (cone-bearing plants) and the early-diverging flowering plant families are conspicuously absent. The disharmony of the flora is directly related to the extreme isolation of the islands; Hawai‘i is the most isolated major island group in the world. The native flora is depauperate and consists entirely of waif elements derived from long-distance dispersal. From approximately 260 successful flowering plant colonists, evolution has led to over 1,190 kinds of native dicots and monocots, about 90% of which are endemic. The flora is so distinctive that it is assigned to its own floristic region by most phytogeographers (e.g., Takhtajan, 1986).

[The term disharmonic describes a biota that does not have the usual diversity of organisms typically found in other places or which are missing specific groups of organisms altogether.]
[Endemic is a term used to describe a species (or related group of organisms) that evolved in a place and which is (are) not naturally found outside that place. In everyday language, we would say that those organisms are unique to that area. The biotas of different areas can be compared by their level of endemism. Native organisms that are also naturally found outside the area in question are referred to as indigenous, regardless of where they first evolved. Native is a term that includes both endemic and indigenous organisms.]
[Taxa (plural) or taxon (singular) refers to organisms classified into a group and given a collective name and a hierarchical rank. A species is one taxonomic rank and species can be (but are not always) made up of two or more subspecies, varieties, or forms. Each of these is a different taxonomic rank. Species are members of a genus and genera are members of a family. This system is a simplified way of indicating how all organisms on Earth are related to one another.]

Despite the proximity of the Hawaiian Islands to North America, the estimated percentage of original colonist lineages from that part of the world is estimated at only 11.2% by Price and Wagner (2018). Original colonists of Indomalayan and Indo-Pacific affinity accounts for 15.1% of native lineages. Other source areas include Pacific islands (12.8%), Neotropics (12.7%), Australasia (7.7%), and East Asia (3.1%); widespread taxa or those of unknown origin account for 34.3% of Hawaiian lineages. Interestingly, despite the tiny percentage of lineages derived from East Asia, it includes the single colonist that produced the largest Hawaiian lineage—the Lobelioideae, which comprises 160 endemic taxa, or 13% of Hawai‘i’s native flowering plant taxa.

Each initial colonist arrived by floating on the ocean, through attachment to the feathers, feet, or in the digestive tract of birds. Humans would eventually bring many more plant species to the islands.

In 2020, as we begin work on Plants of Hawai‘i, the native and naturalized vascular plant flora comprises 202 families (138 dicots, 32 monocots, 4 gymnosperms, 28 ferns & lycophytes); 1,043 genera (729 dicots, 227 monocots, 10 gymnosperms, 77 ferns & lycophytes); and 3,092 taxa (2,209 dicots, 605 monocots, 19 gymnosperms, 259 ferns & lycophytes) (Table 5). Of these, 107 families and 277 genera (165 dicots, 51 monocots, 61 ferns & lycophytes) include native species, and the native vascular plant flora of Hawai‘i consists of 1,405 taxa of dicots, monocots, ferns & lycophytes (Table 1).

[Angiosperms are flowering plants, the gymnosperms are the cone-bearing plants, and these two groups, together with a few extinct groups, are called the seed plants. Some plants do not produce seeds and instead disperse as spores. These include ferns, lycophytes, true mosses, liverworts, and hornworts. The angiosperms, gymnosperms, ferns, and lycophytes all produce vascular tissue (phloem and xylem) and these together are referred to as the vascular plants.]

In general, the largest families in the Hawaiian flora are the same ones that tend to dominate in most other parts of the world (Table 3). This is especially true when considering the total of both native and naturalized species. When considering only the native members of these families, however, there are a few notable differences in the representation of these families in Hawai‘i relative to their presence worldwide. For example, with 160 taxa, the Campanulaceae contains a surprisingly large number of native species, much larger than would be expected relative to the size of the family worldwide, while the Fabaceae (24 taxa), Myrtaceae (16 taxa), and Solanaceae (9 taxa) have an unusually small complement of native species.

Of the native genera, 31 are endemic (Table 1). The overall level of generic endemism is over 11%, the highest in the world. Several endemic Hawaiian genera, however, have been scrutinized through molecular studies on a worldwide basis in the past 30 years. In some analyses, Hawaiian endemic genera are nested within other larger genera. As a result, some genera (e.g., Munroidendron and Tetraplasandra = Polyscias (Araliaceae); Rollandia = Cyanea (Campanulaceae); Alsinidendron = Schiedea (Caryophyllaceae); Platydesma = Melicope (Rutaceae) have been sunk into synonymy, and others (e.g., Labordia = Geniostoma, Broussaisia = Hydrangea) have recently been proposed. However the taxonomy is viewed, it is indisputable that many of the Hawaiian lineages are distinctive. Even if several the lineages treated here as endemic genera are eventually submerged into other genera, they will still claim infrageneric distinction due to their exceptional morphological and ecological differentiation. Other Hawaiian lineages treated here as members of more widespread genera, such as Bonamia, Canavalia, Geranium, Lysimachia, Santalum, and Tetramolopium, are distinctive and recognized formally with endemic infrageneric ranking.

[To be nested means that an organism (or group of organisms) was thought to be distinct from another group and was later found, usually through a DNA sequence analysis, to be a part of the group it was thought to be different from.]
[Synonymy – For various reasons the accepted scientific name of an organism changes over time. Sometimes two researchers may independently give the same group of organisms different names or our understanding of the organisms requires us to merge or split different groups of organisms. All of this results in synonyms which are names that are no longer valid or accepted. Even though the synonyms are no longer used, we need to keep track of them so that we can understand what people were referring to in older scientific literature.]

The level of generic endemism is extremely high in Hawai‘i when only the native dicot genera are considered (16%). A similar pattern is seen at the species level, with 976 native dicot species (94%) considered endemic (Table 1). By contrast, monocots exhibit much lower endemism, with only 2 genera (4%) and 115 taxa (75%) endemic. Similarly, ferns & lycophytes include 2 endemic genera (2%) and 168 taxa (79% endemism). This difference at the species level is undoubtedly related, at least in part, to the considerably higher dispersibility of species in the Cyperaceae and the ready dispersibility of fern and lycophyte spores. The overall level of endemism, using the current figures established by the Manual, is 90% at the taxa level, still the highest of any floristic region in the world. This indicates that, in the Hawaiian flora, speciation far exceeds the immigration of new taxa.

The Hawaiian flora has long been known as an outstanding example of diversification and adaptive radiation; however, as shown here, this phenomenon involves only a very small proportion of the original colonists. The fate of the roughly 260 original flowering plant colonists is strikingly variable. Over 35% of the native vascular plant taxa (419 taxa) are derived from the top six most successful colonists (see Table 4). This pattern of high speciation from only a few taxa (lineages) is typical of isolated islands. These evolutionarily successful genera are distributed in a wide variety of families, with the most conspicuous radiations in the silversword alliance (Asteraceae) and the Lobelioideae (Brighamia, Clermontia, Cyanea, Delissea, Lobelia, Trematolobelia); the latter group includes 142 species (160 taxa, representing 13% of the native flowering plant taxa), all of which presumably arose from a single colonist. Other notably speciose groups are in the Gesneriaceae, Rutaceae, Lamiaceae, and Rubiaceae. By contrast, there are over 160 non-speciose Hawaiian genera that have existed in these islands without speciating or with only a single speciation event. With so much emphasis on the examples of spectacular radiation in Hawaiian plants, examples of colonization with little or no subsequent speciation have largely been ignored.

[An adaptive radiation is said to occur when a lineage of organisms evolves from a single ancestor into many forms, each of which becomes specialized on a different set of environmental factors.]

Over the years, a number of estimates have been made of the size of the Hawaiian flowering plant flora, ranging from 705 species (Hillebrand, 1888) to 1,394 species (St. John, 1973a), and even to 20,000 to 30,000 (Degener & Degener, 1975a). Table 5 gives the numbers of total taxa of native and naturalized dicots, monocots, gymnosperms, and ferns & lycophytes. This most recent estimate is based on our current understanding of species concepts informed by thousands of scientific publications and years of observations in the field and of vouchered herbarium specimens. We believe that these numbers are quite stable; however, estimates are subject to change and new discoveries and new methods are likely to amend these results.

[Scientists refer to species concepts to explain the criteria used to determine which organisms should be classified as members of a distinct species. The most basic species concept is that all organisms that are part of an interbreeding group of individuals should be classified as a single species. This concept doesn’t always work well, especially when very different organisms (either morphologically or ecologically different) are capable of hybridizing and therefore many other species concepts have been proposed to accommodate this and other special cases.]

Today, naturalized taxa comprise about 55% of the native and naturalized vascular plant flora. The number of naturalized species is far greater than previously estimated, and there are probably a fair number of naturalized species still unknown to us. Since the publication of the Manual of the Flowering Plants of Hawai‘i (the Manual) in 1990, over 630 new records of naturalized vascular plants have been published in Hawai‘i Biological Survey publications. Contributing to the large naturalized component in the Hawaiian flora are the equable climate, the high number of species directly and indirectly introduced by man to Hawai'i, and the extensive and continuous perturbation or destruction of many natural habitats, which opens up many sites for colonization by alien plants.

[When an organism is introduced to an area by humans, either intentionally or unintentionally, or through human alteration of the environment, that organism is not considered native. Instead, it is called non-native or introduced and has, in the past, been called alien or exotic. But we don’t use those terms anymore. If a non-native organism reproduces on its own and forms self-sustaining populations, it is said to be naturalized. Some naturalized species become a nuisance to people or take away habitat from native species. These organisms are referred to as invasive species.]

TABLE 1. Statistics summarizing the native vascular plants of Hawai'i (June 2020)

	Dicots	Monocots	Ferns	Total
Families	68	16	23	107
Genera	165 (60%)	51 (18%)	61 (22%)	277
Endemic genera	27a	2b	2c	31
Total end/end? Taxa	976 (94%)	115 (75%)	168 (79%)	1259 (90%)
Total ind/ind? Taxa	63 (6%)	39 (25%)	44 (21%)	146 (10%)
Grand total taxa	1039	154	212	1405
Possibly extinctd	123	7	4	134 (10%)
Fed Endangered	356	29	16	401 (29%)
Fed Threatened	11	0	0	11 (1%)
Fed Proposed Endangered	27	5	7	39 (3%)

a = Argyroxiphium, Bobea, Brighamia, Broussaisia, Clermontia, Cyanea, Delissea, Dubautia, Haplostachys, Hesperomannia, Hibiscadelphus, Hillebrandia, Isodendrion, Kanaloa, Kokia, Labordia, Lipochaeta, Neraudia, Nothocestrum, Nototrichium, Pteralyxia, Remya, Schiedea, Stenogyne, Touchardia, Trematolobelia, Wilkesia; Munroidendron & Tetraplasandra sunk into Polyscias, Rollandia sunk into Cyanea, Alsinidendron sunk into Schiedea, Platydesma sunk into Melicope.

b = Chrysodracon (split out from Pleomele), Dissochondrus.

c = Adenophorus, Sadleria; Diellia sunk into Asplenium.

d = data from Wood, Oppenheimer & Keir. 2019. A checklist of endemic Hawaiian vascular plant taxa that are considered possibly extinct in the wild.

TABLE 2. Statistics summarizing the naturalized vascular plants of Hawai'i (June 2020)

	Dicots	Monocots	Gymno-sperms	Ferns/Lycophytes	Total
Families	128	27	4	17	176
Genera	630 (73%)	198 (23%)	10 (1%)	29 (3%)	867
Total nat/nat? Taxa	1051	380	16	47	1494
Total pol/pol? Taxa	11	14	0	0	25*
? taxa	108	57	3	0	168
Grand total taxa	1170	451	19	47	1687

*Total includes 4 species that have yet to be documented as naturalizing: Artocarpus altilis (‘ulu, breadfruit), Dioscorea alata (uhi, winged yam), Lagenaria siceraria (ipu, gourd), and Saccharum officinarum (ko, sugar cane).

TABLE 3. Twenty-five largest families in Hawai'i (native + naturalized vascular plants, June 2020)

Family	Total spp./taxa	Native spp./taxa	Naturalized spp./taxa
Poaceae	287/294	49/52	238/242
Asteraceae	227/264	98/133	129/131
Fabaceae	189/190	24/24	165/166
Campanulaceae	148/166	142/160	6/6
Lamiaceae	96/100	142/160	34/34
Cyperaceae	88/95	44/51	44/44
Rubiaceae	82/93	59/70	23/23
Malvaceae	75/81	26/32	49/49
Myrtaceae	65/74	8/16	57/58
Rutaceae	63/66	58/61	5/5
Gesneriaceae	59/61	59/61	0/0
Caryophyllaceae	58/59	41/42	17/17
Euphorbiaceae	51/62	17/28	34/34
Amaranthaceae	49/52	13/16	36/36
Solanaceae	42/42	9/9	33/33
Primulaceae	41/41	34/34	7/7
Arecaceae	39/39	24/24	15/15
Convolvulaceae	35/35	10/10	25/25
Piperaceae	31/31	25/25	6/6
Brassicaceae	30/31	6/6	24/25
Acanthaceae	30/31	0/0	30/31
Apocynaceae	30/30	8/8	22/22
Dryopteridaceae	28/37	27/36	1/1
Aspleniaceae	28/37	28/37	0/0
Pteridaceae	28/29	15/16	13/13

TABLE 4. Nineteen most speciose groups of Hawaiian native vascular plants (June 2020).

Genus	# of spp./taxa	Est. # of colonists^a
Lobelioideaeb	142/160	1
Lamioideaec	59/63	1
Cyrtandra	59/61	1
Melicope	54/55	1
Schiedea	34/35	1
Silversword allianced	33/45	1
Asplenium	26/35	17
Peperomia	25/25	4
Pritchardia	24/24	1
Kadua	22/25	1
Bidens	19/27	1
Myrsine	19/19	1
Labordia	17/19	1
Euphorbia	16/27	2
Coprosma	16/16	2
Cyperus	14/18	7
Melanthera	14/15	1
Sicyos	14/14	1
Lysimachia	14/14	1
Totals	621/697	46

a = estimates from Price, J.P. & Wagner, W.L. 2018. J. Syst. Evol. 56(6): 600–620.

b = Brighamia (2/2), Clermontia (22/31), Cyanea (80/86), Delissea (15/16), Lobelia (15/17), Trematolobelia (8/8)

c = Haplostachys (5/5), Phyllostegia (32/35), Stenogyne (22/23)

d = Argyroxiphium (5/6), Dubautia (26/37), Wilkesia (2/2)

TABLE 5. Numbers of native & naturalized Hawaiian vascular plant taxa (June 2020)

	Dicots	Monocots	Gymno-sperms	Ferns/Lycophytes	Total
end/end?Taxa	976	115	0	168	1259
ind/ind? taxa	63	39	0	44	146
Total native taxa	1039	154	0	212	1405 (45%)
nat/nat? taxa	1051	380	16	47	1494
pol/pol? taxa	11	14	0	0	25*
? taxa	108	57	3	0	168
Total naturalized taxa	1170	451	19	47	1687 (55%)
Grand total taxa	2209	605	19	259	3092

*Total includes 4 species that have yet to be documented as naturalizing: Artocarpus altilis (‘ulu, breadfruit), Dioscorea alata (uhi, winged yam), Lagenaria siceraria (ipu, gourd), and Saccharum officinarum (ko, sugar cane).

Summary of the Geology and Climate of Hawai‘i

By Kathlene Imada

The eight main islands of our archipelago all lie just below the Tropic of Cancer and most areas enjoy clement weather and ideal conditions for plant life. The island of Nihoa, along with the remaining archipelago (the Northwestern Hawaiian Island), stretches north and west over another 1600 km, most islands lying above the Tropic of Cancer.

The Hawaiian islands form over a relatively stationary volcanic hotspot in the Pacific plate. Due to the volcanic origins of these islands and the subsequent erosive action of frequent rains and wind, an array of ecological niches exists, leading to many diverse habits. According to Gustafson et al. (2014), the following are the main determinants of landscape patterns of plant communities:

The relative availability of water, as determined by both elevation and slope facing,
Soil factors relating to composition, age of parent material and other traits of soil organic matter and drainage,
Temperature, with low temperatures a limiting factor on high volcanoes.

Thus, they describe the following habitats:

Coastal strand and shore cliffs, where plants are exposed to intense solar radiation, salinity, nutrient-poor soil, and possible burial by moving sand,
Coastal shrublands and woodlands, lying above the strand area up to about 300 m elevation, where extended drought and less salinity exist,
Lowland dry forests and shrublands along the leeward slopes and rain shadow areas of the islands, generally below 1500 m elevations,
Mesic seasonal forests that lie on the windward slopes below, as well as above, wet forest, and also on leeward slopes above dry forests,
Montane wet forests, generally lying between 1000–1900 m within the boundaries of the cloud zone that is produced by trade wind inversions,
Bogs, lying in areas of poor drainage in the montane wet forests of the five largest islands,
Subalpine communities which are separated from the lower forest areas by the upper level of the cloud zone @ about 1800–2000 m,
And lastly, the alpine zone which occurs above the tree line, and consists of broken lava features, cinder cones, and cinder fields with little soil.

These habitats can be further subdivided but serve as a starting point for understanding the habitat diversity in Hawai‘i and on tropical Islands throughout the world. Within these diverse habitats, an array of indigenous and endemic plants evolved and flourished before the arrival of people.

But, from the time of the first Polynesian settlements, the many human introductions of plants and animals has led to 1) extinction of much of the once-rich natural flora and 2) a burgeoning number of non-native, and sometimes invasive/weedy additions to the flora.

With these changes comes an urgent need for land management agencies to identify and manage natural areas as well as to control new introductions that would be harmful to the native environment.

With the publication in 1990 of the Manual of the Flowering Plants of Hawai‘i (Wagner, Herbst & Sohmer), a major step was made in providing a comprehensive work useful to the various entities in Hawai`i, who do this important work.

However, the many new plant introductions, and the rapid development of molecular means to study plant relationships, immediately made this static compendium obsolete. In the ensuing years, it became apparent that an online product could be more easily updated, affording researchers and field workers alike a current, and more valuable tool, one that could also be more readily available in the field. Thus, Plants of Hawai‘i is the next step in this evolution of documenting all plant life of Hawai‘i Nei.

Trends of Endangerment and Invasion

By Kelsey Brock

A variety of human activities have left Hawai‘i’s flora in flux. Populations of endemic species have declined rapidly, with 134 endemic species likely extinct in the wild —12 of which have disappeared in the last six years. These extinct species amount to 11% of Hawai‘i’s endemic plants, but another 18-25% are threatened or endangered, most of which have 50 or fewer wild individuals remaining. While these species illustrate a tragic trend of biodiversity loss, many more species are being gained as humans transport them from elsewhere. Naturalized species now account for over 55% of Hawai‘i’s total terrestrial vascular flora, reflecting steady escapes of species both accidentally and purposefully introduced. Some invaders, such as strawberry guava (Psidium cattleyanum), directly or indirectly contribute to declining native populations. However, we don’t yet know how most of these newcomers will impact native species, leaving us to wonder: is Hawai‘i accruing an extinction debt that will be paid once more invaders have had time to spread?

These challenges, although formidable, have made Hawai‘i into an exciting hub of conservation innovation. Well-connected networks of conservationists [link to Laukahi] and invasive species managers [link to HISC] operate throughout the archipelago to stem species losses and control invaders. Rediscoveries of species once thought to be extinct, as well as cutting-edge propagation techniques and invasive species management technologies give hope that Hawaiian ecosystems will persist despite growing pressures. Hawai‘i’s formerly species-specific paradigm is shifting to a biodiversity informatics approach accounting for all species, and POH is proud to fulfill a crucial role in providing the bedrock data for generating new conservation solutions.

Botanical Research in Hawai‘i

By Nick Walvoord

The first people significant to Botanical research in Hawai`i were the early settlers from the Marquesas and Tahiti. They had the opportunity to be the first to see the many endemic plants found only in the islands and they named and developed uses for many of them. They also brought with them a suite of cultivated plants (known as “canoe plants”) to ensure their survival and the continuation of their cultural practices

These "canoe plants" were important both for their survival on their long voyages and in their new home, as well as for their use in these settlers' cultural practices

Some of these, indicated with a (?), may have been unintentional introductions. A few of these, "including Pandanus tectorius and Cordia subcordata" , were already present in the islands at the time of the Hawaiian’s arrival.

#	Scientific name	Hawaiian name	English name
1	Aleurites moluccana	Kukui	Candle nut
2	Alocasia macrorrhizos	‘Ape	Giant taro, elephant ears
3	Artocarpus altilis	‘Ulu	Breadfruit
4	Broussonetia papyrifera	Wauke	Paper mulberry
5	Calophyllum	inophyllum	Kamani
6	Cocos nucifera	Niu	Coconut
7	Colocasia esculenta	Kalo	Taro
8	Cordia subcordata	Kou	Beach cordia, sea trumpet
9	Cordyline fruticosa	Ki	Ti
10	longa	‘olena	Turmeric
11	Dioscorea alata	uhi	Winged yam
12	Dioscorea bulbifera	hoi	Bitter yam
13	Dioscorea pentaphylla	pi‘a, pi‘a Hawai‘i
14	Hibiscus tiliaceus	Hau	Sea hibiscus, beach hibiscus
15	Ipomoea batatas	‘uala	Sweet potato
16	Lagenaria siceraria	Ipu	Gourd
17	Ludwigia octovalvis (?)		Mexican primrose-willow
18	Morinda citrifolia	Noni	Indian mulberry
19	Musa ×paradisiaca	Mai’a	Banana
20	Musa troglodytarum	mai‘a hē‘ī, mai‘a Polapola	Fe'i banana
21	Oxalis corniculata (?)	‘ihi ‘ai, ‘ihi ‘awa, ‘ihi maka ‘ula, ‘ihi mākole	Yellow wood sorrel
22	Pandanus tectorius	Hala	Screwpine
23	Piper methysticum	‘awa	Kava
24	Rorippa sarmentosa (?)		Polynesian cress
25	Saccharum officinarum	Ko	Sugar cane
26	Schizostachyum glaucifolium	‘ohe	Polynesian bamboo
27	Solanum americanum (?)	Popolo	American black nightshade
28	Syzygium malaccense	‘Ohi‘a ‘ai	Mountain apple
29	Tacca leontopetaloides	pi‘a	Polynesian arrowroot
30	Thespesia populnea	Milo	Portia tree
31	Tephrosia purpurea	‘Auhuhu, ahuhu	Wild indigo
32	Zingiber zerumbet	‘Awapuhi	Shampoo ginger

Before the late 18th century, information about the natural world in Hawai‘i was recorded in the memories, chants, and stories of the people who passed this information orally from generation to generation. This is a practice that continues to this day. Some of this information was written down after 1778 (Kraus, 1993) when the first Europeans arrived and likely much information was lost when introduced diseases caused many people to perish and sudden changes to the culture and subsequent proscriptions on cultural practices interrupted the generational transmission of knowledge.

The first written accounts of the flora and the first botanical specimens were collected on James Cook’s 3rd voyage by William Anderson in January 1778 and David Nelson in January 1779, of these specimens at least 137 still exist (not including duplicates). Following the Cook Expedition’s European discovery of Hawai‘i several other nations, mostly European, sent expeditions to Hawai‘i while conducting exploration in the Pacific. Some of the more noteworthy botanists include A. Menzies (first European to reach the summit of Mauna Loa), C. Gaudichaud-Beaupré, J. Macrae, D. Douglas, G.W. Barclay, W.D. Brackenridge, C. Pickering, W.T. Brigham who later became first curator and director of the Bernice Pauahi Bishop Museum, and H. Mann . Specimens collected on these trips were initially deposited in European and American herbaria although some did, in time, return to Hawai‘i.

Towards the middle of the 1800s, as Hawai‘i developed into a key port in the Pacific, outside settlers began to inhabit the islands and brought with them an interest in botany or developed that interest while living in the islands. In 1885, Indigenous Flowers of the Hawaiian Islands was published by Isabella Sinclair. It is the first publication to feature color images of Hawaiian plants and the first to include the Hawaiian names of the plants. Her focus was on Kaua‘i and Ni‘ihau, recording 37 native species, 7 Polynesian introductions, and one post-European introduced ornamental (St. John, 1954). Her specimens were determined by Sir Joseph Hooker and vouchered at the Royal Botanic Gardens, Kew. Another significant publication was by William (sometimes spelled Willem or Wilhelm) Hillebrand, a Physician/Botanist. He immigrated to Hawai‘i, eventually writing Flora of the Hawaiian Islands based on his own collections as well as specimens collected by Valdemar Knudsen and John Lydgate. His work, published posthumously in 1888, identified 860 native species, 24 Polynesian introductions, and 115 “recent introductions” and is considered to be the first Hawaiian Flora (Hillebrand, W. 1888). Hillebrand’s estate and gardens would eventually become a part of the Foster Botanical Garden. (Hillebrand, W.F., 1887).

What is Plants of Hawai‘i

In 2020, Bishop Museum botanists, with support from the Hawai‘i Invasive Species Council, began work on the Plants of Hawai‘i (POH) project. POH is a website, search engine, and map-based tool that includes information on every flowering plant species documented in Hawai‘i, from Hōlanikū (Kure Atoll) to Hawai‘i island (Big Island). It is a work in progress that will ultimately feature detailed descriptions of each taxon, multi-access ID keys, herbarium specimen data and images, and thousands of contributed field images from Hawai‘i’s botanists, plant enthusiasts, seed banks, arboreta, and botanical gardens.

A POH search will resolve taxonomic synonyms to their currently accepted name and will allow for search by common or Hawaiian names, geographic area, and key identification characters.

For non-native taxa we will typically defer to the taxonomy adopted by the International Plant Names index (IPNI)

For all species, we record from the literature when available ecological and life history information, including whether the taxon is allelopathic, benefits from disturbance, forms thickets, hybridizes readily, sets viable seed, reproduces vegetatively, or fixes nitrogen. We also record ploidy, dispersal agents, known toxicity and allergenicity to people and animals, and human uses, including for landscaping, food or agriculture, forestry, medicine, or textiles. Using the specimens at Bishop Museum, we are generating new plant descriptions (leaves, stems, roots, flowers, fruit, seeds, and seedlings), including key diagnostic characters, habitats, collection localities, elevation range, the date of first and last recorded occurrence, and the establishment status statewide and per island. For non-native taxa, we also record information similar to that used to construct the Hawai‘i Pacific Weed Risk Assessments (HPWRA), including where the plant is likely to invade (agricultural, disturbed areas, or native ecosystems), how it is dispersed, the risks that it may pose (fire promoting, puncture hazard, etc.), and how it is controlled (herbicide, biocontrol, manual).

The Hawai‘i Alien Plant Informatics (HAPI) project (HISC-funded) is now fully integrated with POH, providing a map-based and data-rich species information portal. POH (with HAPI) will ultimately be a key tool for tracking the status, spread, and control of invasive plant species. It will aid in the early identification of potentially invasive species and be a tool for quickly identifying known invasives, enabling appropriate personnel to prevent spread through conveyances, harbors, ports, or airports

POH currently includes basic information for 10,065 accepted flowering plant taxa (all native, naturalized, potentially naturalizing, and cultivated species). Through partnerships with researchers throughout the state we have added basic name data on all ferns and lycophytes (255 taxa) and we plan to add information on bryophytes, and marine, freshwater, and terrestrial eukaryotic algae.

It is out policy to protect the location information for threatened and endangered species, species of concern and certain other species which are likely to be targeted for illegal collection. Plant occurrence data can also occur on private land and a good working relationship between researchers, conservation workers and landholders sometimes necessitates that the exact locality information be masked from the general public. Given these considerations we have enacted measures to mask the exact locations of all plant collections. We are currently working with the appropriate agencies to identify a way forward that will allow distribution information to be made available in a way that does not compromise sensitive data but which is sufficient to educate the public while also informing conservation and research decisions.

POH aims to be a user-friendly plant information portal that allows users to learn about plants, easily identify them, learn about which plants are native, low-risk cultivated species, or high-risk potential invaders. POH will be the anchor for several educational products being developed jointly with our culture and education staff. These resources will support distance or in-class formal education by matching activities with state grade-level standards and facilitate informal active learning at the Bishop Museum campus by people of all ages.