Delissea rhytidosperma
Genus
Delissea
Species
rhytidosperma
Hawaiian Names with Diacritics
- ʻOha
Hawaiian Names
- Oha
Common Names
- Kauaʻi delissea
Synonyms
- Delissea kealiae
Distribution Status
Endemic
Endangered Species Status
Federally Listed
Plant Form / Growth Habit
- Shrub
Mature Size, Height (in feet)
- Shrub, Dwarf, Less than 2
- Shrub, Small, 2 to 6
- Shrub, Medium, 6 to 10
Mature Size, Width
This is a sparsely branched shrub.
Life Span
Long lived (Greater than 5 years)
Landscape Uses
- Accent
- Container
- Indoor
- Specimen Plant
Additional Landscape Use Information
This is one of the easiest and rewarding plants in the Lobelia family to grow and maintain in a landscape. Delissea can be grown as understory plants under trees protected by shrubs and ferns. Though not lowland plants, they do well at near sea level in pots or in the landscape provided they have good drainage. [David Eickhoff, Native Plants Hawaiʻi]
Source of Fragrance
- No Fragrance
Plant Produces Flowers
Yes
Flower Type
Not Showy
Flower Colors
- Greenish-White
- Light Purple
Additional Flower Color Information
This delissea has 5 to 12 bell-shaped greenish-white flowers sometimes suffused with pale violet.
Blooming Period
- Sporadic
- June
- July
- August
- September
- October
- November
- December
Additional Blooming Period and Fruiting Information
The blooming period is from mid-June to late December in its natural habitat. Small purple more or less round (globose) berries appear in early July to January. [1] Under cultivation, plants are sporadic but reliable bloomers.
Plant texture
- Medium
- Coarse
Additional Plant Texture Information
Leaves range from 3 to 7 1/2 inches long and are toothed along the margins.
Leaf Colors
- Dark Green
- Medium Green
Additional Leaf Color Information
Leaves often have a reddish or reddish purplish cast to them that is especially evident when grown in full sun.
Additional Pest & Disease Information
Delissea are prone to attacks by slugs, snails, ants, aphids and rats. Spider mites and mealy bugs can distort leaves and make them look spotty and/or crinkly. [Rick Barboza, Hui Kū Maoli Ola]
In the wild, goats graze on the plants and rats eat the stems.
Fertilizer
Drench or foliar fertilizer* applications along with a balanced slow release fertilizer with minor elements is beneficial every six months. Foliar feed monthly with kelp or fish emulsion, or a water-soluble fertilizer with a dilution of one-half to one-third of the recommended strength. [David Eickhoff, Native Plants Hawaiʻi]
* Drench feeding is a diluted liquid fertilizer applied directly to the soil area around the plant; whereas foliar feeding are light applications of diluted liquid fertilizer applied to the foliage (leaves) by means of spraying or another method to coat leaves.
Pruning Information
Do not prune these plants. Remove dead leaves and spent flowers and fruits for a cleaner appearance in the landscape.
Water Requirements
- Moist
Additional Water Information
Moisture should be monitored with this plant. Water delissea thoroughly and then weekly or as needed.
Soil must be well drained
Yes
Light Conditions
- Partial sun
Additional Lighting Information
Plants prefer filtered sunlight. [Rick Barboza, Hui Kū Maoli Ola]
Soils
- Cinder
- Organic
Limitations
Delissea are intolerant of salt spray and strong winds.
Natural Range
- Kauaʻi
Natural Zones (Elevation in feet, Rainfall in inches)
- 150 to 1000, 50 to 100 (Mesic)
- 1000 to 1999, 50 to 100 (Mesic)
- 2000 to 2999, 50 to 100 (Mesic)
- 3000 to 3999, 50 to 100 (Mesic)
Habitat
- Terrestrial
Additional Habitat Information
This delissea is known to grow naturally in diverse mesic forests where very few plants remain in the wild on Kauaʻi.
Special Features and Information
General Information
Delissea are members of the Bellflower family (Campanulaceae) which includes well over 100 Hawaiian endemic species.
Delissea is an endemic Hawaiian genus. Among the fifteen Delissea species, eleven are now extinct and the remaining four are critically endangered. [1]
Etymology
The generic name Delissea is named for Jacques Delisse (1773-1856), a French physican and botanist from Mauritius, who served as naturalist on the D'Entrecasteaux expedition to the South Pacific in 1800-1804.
The specific name is from the Greek rhytidos, wrinkled, and sperma, seed, in reference to the wrinkled seeds of this species. However, this wrinkled appearance, looking much like a brain, is also seen in at least two other Delissea spp. [1]
Hawaiian Name:
ʻOha is used by one publication. [3]
Background Information
Early Hawaiian Use
There are no known uses for this delissea. However, it is quite likely that early Hawaiians were well aware of them.
Modern Use
The two Kauaʻi species (Delissea kauaiensis, D. rhytidosperma) are both in cultivation. [1,2]
Does well as an indoor plant with bright, but filtered light or full morning sun with sufficient moisture, light drench feedings of fertilizer once or twice a month, and gentle air movement. Though protected from most pests indoor, still keep an eye open for spider mites. [David Eickhoff, Native Plants Hawaiʻi]
Additional References
[1] "Revision of Delissea (Campanulaceae-Lobelioideae)" by Thomas G. Lammers, pages 1, 4, 16, 19-21, 25-26.
[2] Thomas G. Lammers [pers. comm.]
[3] "Hawaiian Plant Life--Vegetation and Flora" by Robert J. Gustafson, Derral R. Herbst & Philip W. Rundel, page 84.
PHOTOS FOR THIS SPECIES CAN BE SEEN AT THE LINK (Copy & Paste to your browser):
https://www.flickr.com/search/?user_id=50823119%40N08&sort=date-taken-desc&view_all=1&text=Delissea%20rhytidosperma
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