This is the first draft of a grass atlas of Hawai'i using data from herbarium specimens, iNaturalist, vegetation plots, conservation organizations, and roadside surveys by the author. These maps are designed to be used to help understand the elevation ranges at which each species occurs and the approximate distribution of each species across the landscape. This is version 1.0, future versions will include both more data and are planned to use species distribution modeling to fill in the gaps between recorded populations. If you would like to help contribute to this project, please upload photos of grasses to inaturalist.org and I will both confirm their identity and then add them to this dataset. If you have any questions, comments, or find errors on this page please email me
DISCLAIMER: The maps presented here DO NOT represent the entire geographic range of each species in Hawai’i. For many species, the range shown here is only a small portion of the area it is truly found. As there has never been a rigorous mapping effort for the vegetation of Hawai’i, the data presented in this atlas derive from many separate sources which are strongly spatially biased around roads, cities, trails, as well as the National Parks. Although steps have been taken to remove obviously erroneous occurrences, some have likely persisted. No effort was made to remove occurrence data for populations which may have died off. The temporal range of this data is 1900 - 2023. While every effort has been made to ensure the quality and accuracy of these maps, they are not guaranteed for any purpose.
Data featured on this page were obtained from herbarium specimens, data from iNaturalist.org reviewed by the author, data from roadside surveys by the author, occurrence data from the Invasive Species Committees, along with vegetation plot data from the National Parks Inventory & Monitoring program, Hawaii forest bird survey, and the Ko'olau Mountain Watershed Partnership. To clean the data, records with coordinate uncertainty greater than 1000 meters were removed. The points manually checked to ensure the coordinates were in reasonable areas and remove any points which were suspected to be misidentified. Climate data from the Hawai'i climate data portal were also used to identify outliers which were growing in areas too hot, cold, wet, or dry and these outliers were removed if the location was deemed to be inaccurate.
There are approximately 20000 herbarium specimens of grasses which were collected across Hawai'i, but the majority of these predate the GPS era and do not yet have coordinates associated with them. Approximately 5000 of these points are included as various projects have added coordinates to these older specimens. Some of the efforts to add coordinates to these specimens have been of higher quality than others and many of the erroneous coordinates which were excluded from these maps came from such efforts. Future versions of this atlas will focus on mapping more of these records.
Synonyms and common names are shown for each species, the common names are specifically those which are used in Hawai'i. For species which do not have widely uses common names here, english names from other regions are included. Synonyms are principally those which have been used historically in Hawai'i. Misapplied names are those which have been based on misidentifcations by past botantists due to the difficulties of identifying introduced grasses in Hawai'i.
The maps show where grasses occur under natural climate conditions. As such, occurrence points of grasses found under irrigated conditions where the climate is otherwise too dry for their growth have been removed. Cultivated occurrences have also been removed when their description mentions them occurring under cultivation, but the cultivation status of some species in the ISC data were not always clear.
Islands are colored by whether each species currently occurs on it. If the species has been observed in the past 50 years it is considered present on the island. If it has not been seen in over 50 years it is considered likely extirpated ("extirpated?" on map legends) and if it has not been seen for a longer period on an island it is considered extirpated. Only one grass (Eragrostis mauiensis is truly extinct. Some are "questionable naturalizations" when it is not clear that the grass has formed a wild population or lack an herbarium specimen. "Waif" occurrences are largely of grain species which keep reappearing from birdseed or spilled grain but do not form sustaining populations.
Also see my other grass resources here.
Copyright Kevin Faccenda. Updated December 2023
Arrhenatherum elatius (L.) P.Beauv. ex J.Presl & C.Presl subsp. elatius vernacular: tall oat grass, false oat grass |
Avena barbata Pott ex Link vernacular: wild oat |
Avena fatua L. vernacular: wild oat |
Avena sativa L. vernacular: cultivated oat, common oat, domestic oat, 'oka |
Bouteloua dactyloides (Nutt.) Columbus synonyms: Buchloe dactyloides, Bulbilis dactyloides vernacular: American buffalo grass |
Chrysopogon aciculatus (Retz.) Trin. synonyms: Rhaphis aciculata, Andropogon acicularis vernacular: pilipili'ula, pi‘ipi‘i, Wild Oat Grass, Manienie 'ula, golden beardgrass |
Cortaderia jubata (Lemoine) Stapf vernacular: jubata pampas grass, jubata grass |
Cortaderia selloana (Schult. & Schult.f.) Asch. & Graebn. vernacular: pampas grass |
Cymbopogon refractus (R.Br.) A.Camus vernacular: barbwire grass, soap grass, wild citronella grass |
Diplachne fusca (L.) P.Beauv. ex Roem. & Schult. subsp. uninervia (J.Presl) P.M.Peterson & N.Snow synonyms: Leptochloa fusca subsp. uninervia, Leptochloa uninervia vernacular: sprangletop |
Disakisperma dubium (Kunth) P.M.Peterson & N.Snow synonyms: Leptochloa dubia vernacular: green sprangletop |
Dissochondrus biflorus (Hildebr.) Kuntze synonyms: Setaria biflora vernacular: no known common names |
Ehrharta calycina Sm. synonyms: Ehrharta melicoides vernacular: perrenial veldtgrass |
Ehrharta erecta Lam. vernacular: panic veldtgrass |
Enneapogon cenchroides (Licht.) C.E.Hubb. vernacular: nine-awned grass, soft feather pappus grass, pappus grass |
Eriochloa acuminata (J.Presl) Kunth var. acuminata vernacular: taper-tip cupgrass |
Eriochloa procera (Retz.) C.E.Hubb. vernacular: tropical cupgrass |
Eriochloa punctata (L.) Ham. vernacular: cupgrass |
Garnotia stricta Brongn. var. acutigluma (Steud.) Veldkamp synonyms: Garnotia acutigluma, Garnotia sandwicensis vernacular: no known common names |
Gastridium phleoides (Nees & Meyen) C.E.Hubb. synonyms: Gastridium ventricosum [misapplied in Hawai'i] vernacular: nitgrass |
Glyceria notata Chevall. synonyms: Glyceria fluitans, Panicularia fluitans vernacular: Plaited Mannagras |
Hemarthria altissima (Poir.) Stapf & C.E.Hubb. vernacular: limpo grass, bigalta, greenalta |
Heteropogon contortus (L.) P.Beauv. ex Roem. & Schult. vernacular: pili, pili grass, tanglehead, lule |
Hordeum murinum L. subsp. leporinum (Link) Arcang. synonyms: Hordeum leporinum vernacular: barley, pale |
Hordeum vulgare L. subsp. vulgare synonyms: Hordeum sativum vernacular: barley, hua pale |
Isachne distichophylla Munro ex Hillebr. vernacular: 'ohe |
Isachne pallens Hillebr. vernacular: no known common names |
Janochloa antidotale (Retz.) Zuloaga & Delfini synonyms: Panicum antidotale vernacular: giant panic grass |
Lachnagrostis filiformis (G.Forst.) Trin. synonyms: Agrostis avenacea, Agrostis retrofracta, Calamagrostis forsteri vernacular: He'upueo, blown grass |
Microlaena stipoides (Labill.) R.Br. synonyms: Ehrharta stipoides vernacular: meadow ricegrass, Ehrharta, Ersty |
Miscanthus floridulus (Labill.) Warb. ex K.Schum. & Lauterb. vernacular: Pacific island silvergrass, giant miscanthus |
Oloptum miliaceum (L.) Röser & Hamasha synonyms: Piptatherum miliaceum, Oryzopsis miliacea, Stipa miliacea, Achnatherum miliaceum vernacular: smilo grass |
Phyllostachys aurea (André) Rivière & C.Rivière vernacular: golden bamboo, dwarf bamboo |
Phyllostachys nigra (Lodd. ex Lindl.) Munro var. henonis (Mitford) Rendle vernacular: black bamboo |
Saccharum spontaneum L. synonyms: Saccharum biflorum vernacular: wild cane |
Saccharum sinense Roxb. vernacular: uba cane |
Sacciolepis indica (L.) Chase synonyms: Sacciolepis contracta vernacular: Glenwood grass |
Stenotaphrum secundatum (Walter) Kuntze synonyms: Stenotaphrum americanum vernacular: St. Augustine grass, buffalo grass, manienie akiaki, 'aki'aki haole |
Thysanolaena latifolia (Roxb. ex Hornem.) Honda vernacular: bamboo grass, tiger grass, Nepalese broom grass |