Couplets have not yet been developed beyond the last choice you made (use the back button to return to that page). Possibly, your choices do not match any known grass from either Hawai‘i or Guam (redo the key and see what results you get). Our Key to the Grasses of Hawai‘i and Guam covers 187 taxa (species, subspecies, and varieties) of grasses and 89 taxa of grasses found on Guam (nearly 69%). The majority of grasses found in Hawai‘i below about 760 m (2500 ft) elevation should be identifiable with the key; and species are being added all of the time. If you reached this page, you might START OVER and check for a list at the bottom of each page giving species not covered in the key.
Figure O. Buffel grass (Cenchrus ciliaris) in anthesis. Yellow structures are the stamens, releasing pollen.
The author would appreciate constructive input where problems are encounterted in the key or a specimen in hand cannot be correctly identified using the key. You may send comments to the author (guinther@aecos.com). If you encounter a grass you cannot identify with this key you may place it in an envelope (there must be an inflorescence, but specimen can be dried) with a note that includes location and island and your email address for a return answer (if I can identify it). Mail the specimen to "E. Guinther, 45-309 Akimala Pl. Kāne‘ohe, Hawai‘i, 96744".
One way the keys in A Key to the Grasses, Sedges, & Rushes of the Hawaiian Islands and Guam are expanded is by combing the literature covering grasses in the Hawaiian and Marianas Islands. This effort regularly reveals species recorded in the literature but not yet (if ever) included in our keys. On many pages in the key, these species appear at the bottom of a page as species not included. Others—grass species not included in our key (along with some references that recorded the species; consult citation for primary sources) or listed anywhere else in our document—are presented here:
These Hawai‘i species are considered valid species and not of questionable distribution in the islands, unless marked QUESTIONABLE. For Hawai‘i, these species may be rare and have a very limited distribution. Others may be widespread but have yet to be worked into our key. For the Marianas, species known from the archipelago, but not recorded from Guam, are usually included in the keys, but may get listed here.
The most recent, complete list of naturalized grasses in Hawai‘i is that of Faccenda (2023c). The references cited above may include species that have been recorded as occurring in Hawai‘i or Guam, but are of uncertain continued occurrence there today. By way of example, Wagner, Herbst, & Sohmer (1990) list 23 grasses that "have been collected in Hawai‘i only once or a few times, and their current status is uncertain". These 23 species are not included in the Manual grass keys or detailed species descriptions; nor are they included here. However, if a grass is listed by Imada (2019), that species will remain in the index as well as on our key page list (or this page) marked QUESTIONABLE and not included in a key. The list presented above is intended to direct further expansion of our keys and indicate the extent to which our keys are incomplete, more or less independent of the unliklihood of a naturalist encountering a truely rare one.
TABLE OF CONTENTS
: START of GRASS KEY
HAWAI‘I INTRODUCTION
GUAM INTRODUCTION
AECOS, Inc.
