Cyanea angustifolia

{{Short description|Species of flowering plant}} {{Speciesbox |image = Cyanea angustifolia (4822099041).jpg |image_caption = |genus = Cyanea |species = angustifolia |authority = (Cham.) Hillebr. |synonyms_ref = <ref name="urlPlantList"/> |synonyms = *''Lobelia angustifolia'' Cham. ''Delissea angustifolia'' (Cham.) C.Presl ''Delissea honolulensis'' Wawra |status = G2 |status_system = TNC }}

'''''Cyanea angustifolia''''' is a shrub in the genus ''Cyanea'' that is endemic to Hawaiʻi. In Hawaiʻi, it is referred to as ʻAku<ref>{{Cite web |title=ʻAku/Center for Plant Conservation |url=https://saveplants.org/plant-profile/?CPCNum=13668}}</ref> as well as Hāhā, which is the term for the generalized ''Cyanea'' genus.<ref name=":0">{{Cite web |title=Native Plants Hawaii – Viewing Plant : Cyanea angustifolia |url=http://nativeplants.hawaii.edu/plant/view/Cyanea_angustifolia/ |access-date=2026-02-10 |website=nativeplants.hawaii.edu}}</ref> ''C. angustifolia'' was a food source during times of food scarcity for the Hawaiians. This shrub is characterized by specialized flower shapes and it is found at higher elevations in wet environments.

== Description == This shrub has a mature size of 2-3 meters wide, reaching heights of over 3 meters tall.<ref name=":0"/> It has coarse.<ref name=":0" /> glabrous leaves<ref name=":1">{{Cite web |last=Eikhoff |first=David |date=October 13, 2025 |title=Native Plants of Hawaiʻi |url=https://www.nativeplantsofhawaii.org/c/cyanea-angustifolia |access-date=March 10, 2026 |website=nativeplantsofhawaii.org}}</ref> that have transparent veinlets.<ref>{{Cite book |last=Hillebrand |first=William |url=https://www.biodiversitylibrary.org/page/15638353 |title=Flora of the Hawaiian islands :a description of their phanerogams and vascular cryptogams |date=1888 |publisher=Williams & Norgate |year=1888 |location=London |pages=251-254}}</ref>

The flowers are arranged as hanging clusters and are typically purple, pink, or white.<ref name=":0"/> They are characterized by their fused anther and filament which produces a tube around the style and stigma. Pollen is released by the anthers into the fused tube. There are stiff, short hairs at the tips of the anthers that aid in the collection of pollen and allow for pollinators to easily collect and spread the pollen.<ref>{{Cite journal |last=Cory |first=Coleen |last2=Pender |first2=Richard |last3=Jones |first3=C. Eugene |date=April 2015 |title=Can Ornithophilous Hawaiian Lobeliads Produce Seeds in the Absence of Pollinators? A Test Using Clermontia kakeana and Cyanea angustifolia (Campanulaceae) |url=https://www.bioone.org/doi/10.2984/69.2.7 |journal=Pacific Science |language=en |volume=69 |issue=2 |pages=255–261 |doi=10.2984/69.2.7 |issn=0030-8870|url-access=subscription }}</ref> The flowers eventually mature into a globose purple berry and bloom sporadically all year round.

== Distribution and habitat == ''C. angustifolia'' can be found on Oʻahu, commonly in the Ko’olau Mountains and scarcely in the Wai’anae Range. It can also be found on eastern Molokaʻi and Lānaʻi. Additionally, they can be found in northern areas of West Maui. Wet conditions are preferred for the survival of ''C.angustifolia''. This plant's preferred habitat elevation ranges from 45 meters to over 760 meters, growing in mesic forests, mesic valleys, and wet forests.<ref name=":0"/>

== Etymology == ''Cyanea'' derives from the Greek and Latin words for blue and violet. ''Angustifolia'' translates to narrow leaves.<ref name=":0"/> Closely related species include ''Cyanea angustifolia'' var. ''racemosa, Lobelia angustifolia, Delissea acuminata'' var. ''Angustifolia, Delissea angustifolia, Delissea angustifolia'' var. ''racemosa,'' and ''Delissea honolulensis''.<ref>{{Cite web |title=WFO Plant List World Flora Online|url=https://wfoplantlist.org/taxon/wfo-0000830823-2025-12.|access-date=2026-03-02|website=wfoplantlist.org}}</ref>

== Human use and cultural significance == Culturally, ''C. angustifolia'' has been important to Native Hawaiian island populations. Hawaiians would eat the leaves of this plant when food was scarce, wrapping the Hāhā leaves in ti leaves and then cooking them in an .imu'.<ref name=":0" />

In more modern times, this plant is ornamental when found outside of its typical environment and can be kept indoors as a house plant.<ref name=":1" />

== Conservation status == Like most endemic species, ''C. angustifolia'' is threatened by invasive species and is listed as imperiled, with fewer than 10,000 individuals estimated in the wild. Its range is limited to mostly mesic and mesic-wet forests.<ref>{{Cite web |title=NatureServe Explorer 2.0|url=https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.150810/Cyanea_angustifolia|access-date=2026-04-11|website=explorer.natureserve.org}}</ref> Threats include habitat loss and damage from invasive pests. Notably, ''C. angustifolia'' is susceptible to pests such as slugs and snails who often end up girdling the plant in just a single night.<ref name=":1"/> [[File:Cyanea angustifolia (4822098517).jpg|thumb|''Cyanea angustifolia'', known as ''Hāhā'' in Hawaii. It is endemic to the Hawaiian Islands. Photographed on the Waiʻanae-Kai Trail, Waiʻanae Mountains, Oʻahu]]

==References== {{Reflist|refs=

<ref name="urlPlantList">{{cite web |title=''Cyanea angustifolia'' (Cham.) Hillebr. |url=http://www.theplantlist.org/tpl1.1/record/kew-368106 |publisher=The Plant List (2013). Version 1.1. |accessdate=2014-05-17}}</ref>

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angustifolia Category:Plants described in 1833 Category:Endemic flora of Hawaii