Question: Mount Waiʻ aleʻ ale and Kauaʻ i are examples of place names that employ what unicameral consonant letter?
Context: Pritchardia waialealeana, the poleline pritchardia, is a species of palm tree that is endemic to the island of Kauaʻ i in Hawaii, United States.  It inhabits wet forests on the slopes of Mount Waiʻ aleʻ ale at elevations of 500 - .  "P. waialealeana", is a large palm, reaching a height of more than 20 m . The ʻ okina, also called by several other names, is a unicameral consonant letter used within the Latin script to mark the phonemic glottal stop, as it is used in many Polynesian languages. Slack voice (or lax voice) is the pronunciation of consonant or vowels with a glottal opening slightly wider than that occurring in modal voice.  Such sounds are often referred to informally as lenis or half-voiced in the case of consonants.  In some Chinese varieties, such as Wu, and in many Austronesian languages, the 'intermediate' phonation of slack stops confuses listeners of languages without these distinctions, so that different transcription systems may use or for the same consonant.  In Xhosa, slack-voiced consonants have usually been transcribed as breathy voice.  Although the IPA has no dedicated diacritic for slack voice, the voiceless diacritic (the under-ring) may be used with a voiced consonant letter, though this convention is also used for partially voiced consonants in languages such as English. The Alakaʻ i Wilderness Preserve, popularly known as Alakaʻ i Swamp, is a montane wet forest on the Hawaiian island of Kauaʻ i.  Although the preserve is home to alpine bogs, it is not a true swamp.  It is located on a plateau near Mount Waiʻ aleʻ ale, one of the wettest spots on Earth. Waimea Canyon, also known as the "Grand Canyon of the Pacific", is a large canyon, approximately ten miles (16 km) long and up to 3,000 feet (900 m) deep, located on the western side of Kauaʻ i in the Hawaiian Islands of the United States.  Waimea is Hawaiian for "reddish water", a reference to the erosion of the canyon's red soil.  The canyon was formed by a deep incision of the Waimea River arising from the extreme rainfall on the island's central peak, Mount Waiʻ aleʻ ale, among the wettest places on earth. The Hawaiian tropical rainforests are a tropical moist broadleaf forest ecoregion in the Hawaiian Islands.  They cover an area of 6700 km2 in the windward lowlands and montane regions of the islands.  Coastal mesic forests are found at elevations from sea level to 300 m .  Mixed mesic forests occur at elevations of 750 to , while wet forests are found from 1250 to .  Moist bogs and shrublands exist on montane plateaus and depressions.  For the 28 million years of existence of the Hawaiian Islands, they have been isolated from the rest of the world by vast stretches of the Pacific Ocean, and this isolation has resulted in the evolution of an incredible diversity of endemic species, including fungi, mosses, snails, birds, and other wildlife.  In the lush, moist forests high in the mountains, trees are draped with vines, orchids, ferns, and mosses.  This ecoregion includes one of the world's wettest places, the slopes of Mount Waiʻ aleʻ ale, which average 460 in of rainfall per year. In orthography, a zero consonant, silent initial, or null-onset letter is a consonant letter that does not correspond to a consonant sound, but is required when a word or syllable starts with a vowel (i.e. has a null onset).  Some abjads, abugidas, and alphabets have zero consonants, generally because they have an orthographic rule that all syllables must begin with a consonant letter, whereas the language they transcribe allows syllables to start with a vowel.  In a few cases, such as Pahawh Hmong below, the lack of a consonant letter represents a specific consonant sound, so the lack of a consonant sound requires a distinct letter to disambiguate. The Hanalei River on the island of Kauaʻ i in Hawaii flows north from the eastern slopes of Mount Waiʻ aleʻ ale for 15.7 mi until it reaches the Pacific Ocean at Hanalei Bay as an estuary.  With a long-term mean discharge of 216 cubic feet (6.12 cubic meters) per second, in terms of water flow it is the second-largest river in the state; although its watershed of 19.1 sqmi is only sixth-largest on Kauaʻ i, it encompasses areas of the highest recorded rainfall on the planet and plunges precipitously from its headwaters at 3500 ft above sea level. This is a list of the longest place names in Ireland.  It includes names written in English as a single word of at least 20 letters.  The vast majority of English-language place names in Ireland are anglicisations of Irish language names.  The spelling which has legal force is usually that used by the Ordnance Survey of Ireland.  Many of Ireland's longest place names are found in the far west of the island, where the Irish language survived the longest; including Gaeltacht areas, where it is still the vernacular.  These names are generally written as multiple words in Irish. Mount Waiʻ aleʻ ale (why ah lay ah lay), often spelled Waialeale in English without the ʻ okina, is a shield volcano and the second highest point on the island of Kauaʻ i in the Hawaiian Islands.  Its name literally means "rippling water" or "overflowing water"
Answer: ʻ okina