CPC Plant Profile: Kauai Delissea
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Plant Profile

Kauai Delissea (Delissea rhytidosperma)

Full shot of plant. Notice the green flowered inflorescences. Photo Credit: D. Ragone
Description
  • Global Rank: G1 - Critically Imperiled
  • Legal Status: Federally Endangered
  • Family: Campanulaceae
  • State: HI
  • Nature Serve ID: 141823
  • Date Inducted in National Collection: 07/09/1992

The genus Delissea is among the most threatened of Hawaiis endemic genera. There are ten recorded species, of which only four have survived (U.S. Fish and Wildlife Service [USFWS] 2001). D. rhytidosperma, a member of the bellflower family (Campanulaceae) is a branched shrub 0.5 to 2.5 meters (2 to 8 ft) tall, with lance-shaped or elliptic toothed leaves (8 to 19 cm long, 2 to 2.5 cm wide). The petals are greenish white (sometimes pale purple) with hairless stamens, except for a small patch of hair at the base of the anthers (USFWS 1995). This short-lived perennial species differs from other taxa of the genus by the shape, length, and margins of the leaves and by having hairs at the base of the anthers.

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Updates
Center for Plant Conservation
  • 12/02/2021
  • Reintroduction

The purpose of the project was to establish a new population of this Delissea species on managed conservation land at Limahuli Preserve. An unidentified species of Delissea was known from Limahuli Valley but was not relocated for more than 10 years and was presumed extirpated. On December 29, 1999 NTBG field botanists Steve Perlman and David Bender discovered a new population of Delissea in Hanakapiai Valley, a watershed adjacent to Limahuli Valley. This population consisted of only five plants, all of which died over the subsequent two year period. Fortunately the plants had ripe fruits, which were collected, yielding a large batch of seedlings. The decision was made to establish a population at Limahuli Preserve because there is an ongoing restoration program for Limahuli, while Hanakapia Valley though part of Na Pali Coast State Park, is not effectively managed to reduce threats to this species. Plants used in the project were mostly f1s and subsequent generations resulting from plants grown at Limahuli. Roughly 150 plants were introduced in several subpopulations, all in managed restoration sites. Survival rate of these outplants was greater than 80% in the first three years of the project. Plants grew to maturity and set viable seed but no seedling recruitment has been observed. Competition from introduced grasses (Paspalum conjugatum and Oplismenus hirtellus) is the probable culprit. Because seedlings are small and extremly delicate they are nearly impossible to detect within the surrounding cover of introduced grasses. Ongoing management of the site to reduce weed competition may actually destroy these seedlings before they can be detected. A report was submitted to Hawaii Department of Land and Natural Resources with details of this introduction effort.

Nature Serve Biotics
  • 05/02/2017

Endemic to the island of Kauai. This species is now known from only 2 locations, with fewer than 30 plants known to be extant. The major threats to this species are deer, pigs and alien plant species.

  • 01/01/2010

Threats to D. rhytidosperma include predation and habitat degradation by mule or black-tailed deer, feral pigs, and goats, and herbivory by rats and introduced slugs. Fire and competition with the alien plants such as Lantana camara (lantana), Passiflora

  • 01/01/2010

Number of Populations: 2 (USFWS 2001; K.R. Wood pers. comm.) Number of Plants: 15 (USFWS 2001; K.R. Wood pers. comm.)

  • 01/01/2010

Seeds of D. rhytidosperma have been tested by the Center for Conservation Research (CCRT), the National Seed Storage Laboratory (NSSL), and the National Tropical Botanical Garden (NTBG), finding that they are orthodox, and can tolerate freezing and drying. The laboratory germination time was three weeks to six months (Yoshinaga 2002).

  • 01/01/2010

Plants and seedling of D. rhytidosperma have been collected by NTBG. It has also been successfully been propagated by tissue culture (USFWS 1995). NTBG currently has ex situ holdings of numerous seeds in its seed bank, plants growing in the nursery, and seven plants growing in the botanical garden, which represent the single population. Extensive and reproducing populations are maintained in a semi-natural state at Limahuli Garden and Preserve (NTBG).

  • 01/01/2010

1. Survey historic range for surviving populations. 2. Maintain adequate genetic stock of D. rhytidosperma. 3. Conduct pollination biology and seed dispersal studies. 4. Map genetic diversity in the surviving populations of D. rhytidosperma, and identify conservation management units. 5. Test the influence of weeding and fencing on populations of D. rhytidosperma. Recommendations derived from M.H. Chapin, M. Maunder, and USFWS (1995).

  • 01/01/2010

1. Establish secure ex situ stocks with full founder representation. 2. Develop proper horticultural protocols and pest management for D. rhytidosperma. 3. Survey ex situ holdings and conduct molecular fingerprinting. Recommendations derived from M.H. Chapin and M. Maunder.

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Photos
Nomenclature
Taxon Delissea rhytidosperma
Authority H. Mann
Family Campanulaceae
CPC Number 1368
ITIS 34762
USDA DERH2
Common Names Kauai Delissea
Associated Scientific Names Delissea rhytidosperma | Delissea kealiae
Distribution D. rhytidosperma is endemic to Kauai and was historically known on the island from as far north as Wainiha and Limahuli Valleys, as far east as Kapaa and Kealia, and as far south as Haupu Range. It is
State Rank
State State Rank
Hawaii S1
Habitat

D. rhytidosperma generally grows in diverse lowland mesic forests of Acacia koa (koa) dominated lowland dry forests that have well-drained soils with medium-to fine-textured subsoil. They are found in elevations of 120 to 915 meters (394 to 3,002 ft) (USFWS 2000). Associated species of D. rhytidosperma include Euphorbia haeleeleana (akoko), Psychotria hobdyi (kopiko), Pisonia sp. (Papala kepau), Pteralyxia sp. (kaulu), Dodonaea viscose (aalii), Cyanea sp (haha)., Hedyotis sp. (no common name [NCN]), Dianella sandwicensis (ukiuki), Diospyros sandwicensis (lama), Styphelia tameiameiae (pukiawe), and Nestegis sandwicensis (olopua) (USFWS 2000).

Ecological Relationships

None known.

Pollinators
Common Name Name in Text Association Type Source InteractionID
Bees
Bee Confirmed Pollinator Link
Butterflies & Moths
Moth Confirmed Pollinator Link
Birds
Birds Confirmed Pollinator Link
Bird Confirmed Pollinator Link
Reintroduction
Lead Institution State Reintroduction Type Year of First Outplanting
National Tropical Botanical Garden Hawaii Reintroduction

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