Plant Profile
Bidens forbesii
Kokolau, Koʻokoʻolau, Koʻolau, Kōʻokoʻolau
Main Plant Information
Genus
Bidens
Species
forbesii
Subspecies
- forbesii
- kahiliensis
Hawaiian Names with Diacritics
- Kokolau
- Koʻokoʻolau
- Koʻolau
- Kōʻokoʻolau
Hawaiian Names
- Kokolau
- Kookoolau
- Koolau
Common Names
- Coastalbluff beggarticks
Synonyms
- Bidens asymmetrica var. subocculta
- Bidens forbesii
- Bidens napaliensis
Plant Characteristics
Distribution Status
Endemic
Endangered Species Status
No Status
Plant Form / Growth Habit
- Non-Woody, Clumping
Mature Size, Height (in feet)
- Herbaceous, Medium, 1-3
- Herbaceous, Tall, Greater than 3
Life Span
No data available.
Landscape Uses
- Accent
Additional Landscape Use Information
Not yet known to be in residential or commercial landscapes. But perhaps could be used as an accent plant as some other koʻokoʻolau are.
Source of Fragrance
- No Fragrance
Plant Produces Flowers
Yes
Flower Characteristics
Flower Type
Showy
Flower Colors
- Yellow
Additional Flower Color Information
The yellow flowers are attractive en masse.
Leaf Characteristics
Plant texture
- Medium
Leaf Colors
- Medium Green
Pests and Diseases
Additional Pest & Disease Information
Perhaps the same pests that affect other native Bidens spp. such as spider mites, aphids, scale, spittle bugs, slugs and snails.
Growth Requirements
Water Requirements
- Moist
Additional Water Information
“Water Requirements” of this species are based on habitat.
Light Conditions
- Full sun
Additional Lighting Information
“Light Requirements” are based on typical growing needs of Bidens spp. in general.
Environmental Information
Natural Range
- Kauaʻi
Natural Zones (Elevation in feet, Rainfall in inches)
- Less than 150, 50 to 100 (Mesic)
- 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
Bidens forbesii is scattered to commonly found on coastal bluffs and cliffs to diverese mesic forest from sea level to 3280 feet on Kauaʻi.
Two distinctive subspecies are known, with subsp. kahiliensis found only in the vacinity of Mount Kāhili and Kapalaoa from 2460 to 3280 feet.
Special Features and Information
General Information
Koʻokoʻolau ( Bidens spp.) are members of the Aster or Sunflower family (Asteraceae). There are nineteen endemic species of Bidens .
The natives are not invasive as are some of the alien species such as kī ( Bidens pilosa ) with its harpoon-like seeds (kukū) that seem attracted to long pants, socks and shoe laces or the White beggarticks ( Bidens alba ) that blanket huge areas with “cute-but-don’t-grow-them-anyway” white and yellow flowers.
Etymology
The name Bidens is derived from the Latin bi , two, and dens , teeth in reference to the pappus awns or collective bristles on the achenes (fruit, seeds).
The specific epithet forbesii is likely named for Charles Noyes Forbes (1883-1920), a botanist and former curator of the Bishop Museum, Honolulu, Hawaii. [this needs to be confirmed]
Background Information
All Bidens species can hybridize, which should be avoided. Individual species are often restricted to one habitat.
Bidens forbesii subsp. kahiliensis occasionally hybridizes with B. valida on the windward slopes of Mount Kāhili.
Early Hawaiian Use
Leaves of all species of native koʻokoʻolau were used medicinally and for a tea tonic.
Modern Use
All species of koʻokoʻolau can be brewed as a tonic and each are said to have distinct flavors. Regarding Bidens spp., Isabella Abbott comments that “I find that the roughly half a dozen species common in Hawaiʻi offer two or three slightly different flavors, each a bit more subtle than commercial black tea.” [1]
Additional References
[1] “Lāʻau Hawaiʻi: Traditional Hawaiian Uses of Plants” by Isabella Aiona Abbott, page 102.
