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Delissea rhytidosperma

leaf Main Plant Information

Genus

Delissea

Species

rhytidosperma

Hawaiian Names with Diacritics

  • ʻOha

Hawaiian Names

  • Oha

Common Names

  • Kauaʻi delissea

Synonyms

  • Delissea kealiae

leaf Plant Characteristics

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

leaf Flower Characteristics

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.

leaf Leaf Characteristics

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.

leaf Pests and Diseases

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.

leaf Growth Requirements

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.

leaf Environmental Information

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.

leaf 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.

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