Cordia subcordata
Cordiaceae or Geiger-tree family
Synonyms: none
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Kou
In Papua New Guinea this indigenous tree is known as the Kerosene tree because it burns so easily.
Cordia subcordata is known by a number of local names outside of the Hawaiian Islands, such as Bird lime tree, Glueberry, Kerosene wood, Manjak, Mareer, Marer, Narrow-leafed bird lime tree, Snottygobbles, and Tou.
Natural Range & Environment
Southeast Asia, Malesia, coastal tropical East Africa, Indian Ocean islands, Australia (Queensland), throughout Micronesia, and most Pacific archipelagoes. Possibly spread throughout the Pacific region by the early migrations of Austronesian people, but subfossil evidence indicates it antedates humans in the Hawaiian Islands at least. In the Hawaiian Islands, Indigenous to all the main Hawaiian Islands except Kaho‘olawe.
Kou is found throughout most of the Main Islands today, but is only known to have occurred for a certainty as an indigenous plant on Kauaʻi in the past. [3]
The bright orange flowers of kou (photograph courtesy of Ken Chamberlain CC BY-NC 4.0), when pollinated, develop into round marble-sized fruits that turn dark brown to black when ripe (photograph courtesy of Steve Wells Public Domain). It's not unusual to see multiple seedlings, with their odd-looking seed leaves, sprout from a single fruit buried in the beach sand (photograph courtesy of Fur, Fangs, Fins and Feathers CC BY-NC 4.0). Don't be fooled by the introduced Gieger tree (Cordia sebestena), today often planted as a kou replacement. The three visible differences are (1) redder flowers, (2) ripe fruits that are white rather than brown or black, and (3) leaves that are rough and dull instead of smooth and shiny (side-by-side photograph courtesy of J.B. Friday ©).
Tapped into the water of this *** pool near the coastline on Hawai‘i Island, these wild kou trees are growing particularly well (photograph courtesy of J.B. Friday ©). While kou can be an attractive street tree, its hard and slippery fruits can be a safety hazard on sidewalks (photograph courtesy of J.B. Friday ©). Rather, a safer planting site is in a grassy or sandy beach park (photograph courtesy of Forest & Kim Starr CC BY ***).
Description
Tree, Small, 15 to 30
Tree, Medium, 30 to 50
Mature Size, Width
Canopy may spread to 25 feet across, often as wide as tall. In the 19th century, kou grew as tall as 50 feet in Hawaiʻi, but defoliation by kou leaf worm as reduced the heights. Such giants may remain in remote areas in the Marshall Islands and the elsewhere in the Pacific, and perhaps over a century old. [7]
Long lived (Greater than 5 years)
Leaves are smooth and somewhat glossy.
Medium Green
Kou trees with varigated green and white leaves are known. [7]
Flower color ranges from light to bright orange.
Blooming Period
Year Round
Sporadic
Generally, kou fruit all year long, but maybe sporadic. [7] The green fruits soon become brown and then dry to a blackish color when ripe. Inside are four white seeds.
Growth Requirements
General
Provides Shade
Screening
Specimen Plant
Kou is an excellent tree for a roomy landscape. They can get to be medium-large trees and may not be suitable for small urban yards that cannot accommodate a height and canopy spread of 25-35 feet. [7] Good to keep in mind that they have a shallow root system and can be damaged by too much surface disturbance. Once established they require little maintenance.
However, the slippery fruits along with exceptionally hard seeds may present a hazzard if planted too close to driveways or along sidewalks where they can a present a real threat for slipping or going an unintentional "skating trip." [7]
In many urban plantings kou is being replaced by kou haole or the Geiger tree, a similar species with red-orange flowers and rough leaves. This is unfortunate because the Geiger tree is a native of the West Indies and has no cultural value in the Hawaiian Islands. [7]
Kou trees will often grow crooked and pruning is necessary to keep a nice shape. [7]
Dry
Soil must be well drained
Full sun
Partial sun
Prefers full sun but tolerates some shading. [7]
Tolerances
Drought
Wind
Salt Spray
Soils
Clay
Sand
Cinder
Organic
Coral
Moderately drought tolerant trees. Kou will not grow at higher altitudes and cannot withstand frost. Kou can grow in saline soils and tolerate some salt spray, but heavy spray can severley damage leaves. [7]
Pests and Diseases
The Kou leaf worm (Ethmia nigroapicella), from a moth, can defoliate and can be killed kou trees. The wood is very termite reistant. Large trees can develop heartwood rot. [7]
Refer to the Pests & Diseases page for ways to battle the above-mentioned pests.
Kou leaf worm (Ethmia nigroapicella) larva (photograph courtesy of Forest & Kim Starr CC BY ***) and adult (photograph courtesy of Rosario Douglas CC BY 4.0). Kou trees defoliated by kou leaf worm (photograph courtesy of J.B. Friday ©).
Uses
Ancient Hawaiian
Early Hawaiians certainly brought kou with them as one of the canoe plants since it is such a highly esteemed wood. [5,12]
They were planted as a favorite shade tree around houses and by the seashore. [9] Women would beat their kapa under kou trees. [12]
Kou was considered as one of the best woods for carvings along with the native koa (Acacia koa) and milo (Thespesia populnea), and the Polynesian introduced kamani (Calophyllum inophyllum). [7,8,12] Kou was prized because of the beauty of the grain and ease of cutting and carving. [12]
The leaves were used to stain fishing lines a light tan. [5,10,12] The aged leaves were used for a warm brown to red dye for kapa. [1]
Wood was made into fishing hook containers. [12]
The tasteless seeds were eaten in times of famine or occasionally by hungry children.
Wooden food bowls (ʻumeke kou), meat dishes, cups, platters (pā kou), and calabashes were highly prized as the best of all woods because it did not impart a resinous flavor to the food such as koa and most other native woods. [2,4,8,10]
The flowers were used for lei and young girls especially were fond of lei kou. [4,9,12] They were always strung kui style (one behind the other). [10]
Use to treat ʻea (thrush), a disease of young children. [12]
Kou wood was fashioned into images of gods. [12]
Modern
The wood is used to carve artifacts such as calabashes, dishes, cups, bowls, paddles, furniture, and drums. [5,11]
Uses Outside of Hawaiʻi:
In Tahiti, fruit of banyan (Ficus sp.) is added to kou leaves to make a beutiful red dye. [12]
Flower lei and wooden 'umeke (lidded bowl) made from kou (Lei and 'umeke photograph courtesy of J.B. Friday ©).
Special Features and Information
General
Cordia subcordata was previously placed in Boraginaceae (Forget-me-not family).
Formerly thought to be exclusively a Polynesian introduction, a recent fossil site at Māhāʻulepū, Kauaʻi predates Polynesian arrival where kou samples were found and thus proving that kou is also an indigenous plant. [3,6] The seeds are salt-water tolerate and disperse along coastal areas even on atolls where few other timber trees for wood can grow. [5]
In Papua New Guinea this indigenous tree is known as the Kerosene tree because it burns so easily.
Cordia subcordata is known by a number of local names outside of the Hawaiian Islands, such as Bird lime tree, Glueberry, Kerosene wood, Manjak, Mareer, Marer, Narrow-leafed bird lime tree, Snottygobbles, and Tou.
Hawaiian Name
Puʻu
Etymology
The generic name Cordia, is named for Euricius Cordus (1485-1535) and his son Valerius (1515-1544), both German botanists and pharmacists.
The specific epithet is from the Latin sub-, almost or not completely, and cordatus, cordate (with two equal rounded lobes at base) in reference to the leaf shape, literally meaning "almost heart-shaped."
Additional References
[1] "Plants in Hawaiian Culture" by Beatrice H. Krauss, page 65.
[2] "Arts and Crafts of Hawaii" by Te Rangi Hiroa (Sir Peter H. Buck), pages 37-38, 187.
[3] "Fossil Evidence for a Diverse Biota From Kauaʻi and Its Transformation Since Human Arrival" by David Burney et al., Ecological Monographs, 71(4), 2001, Ecological Society of America, pages 631, 632, 633.
[4] "Nā Lei Makamae--The Treasured Lei" by Marie A. McDonald & Paul R. Weissich, page 53-54.
[5] "Plants of the Canoe People" by W. Arthur Whistler, pages 83-84.
[6] "Back to the Future in Caves of Kauaʻi--A Scientist's Adventures in the Dark" by David A. Burney, page 106.
[7] "Traditonal Trees of the Pacific Islands: Their Culture, Environment, and Use," pages 305, 307, 309, 312, 313.
[8] "Resource Units in Hawaiian Culture" by Donald D. Kilolani Mitchell, pages 79-80, 120, 130-131.
[9] "In Gardens of Hawaii" by Marie C. Neal, pages 714-715.
[10] "Lāʻau Hawaiʻi: Traditional Hawaiian Uses of Plants" by Isabella Aiona Abbott, pages 57, 87, 127.
[11] "Contemporary Woodworkers" by Tiffany DeEtte Shafto & Lynda McDaniel, page 182.
[12] "Ethnobotany of Hawaii" by Beatrice H. Krauss, page 133.
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