Systematic and morphology
Hibiscus tiliaceus L. belongs to the family Malváceae and in Tahitian it is called "Purau" (Saquet, 1996). The common name in English is sea hibiscus (Holtum & Enoch, 1995) or tree hibiscus (Hargreaves and Hargreaves, 1970). In Tahiti the species is in nature to be found in three varieties: var. typicus, var. henryanus F. Brown and var. sterilis F. Brown (Brown, 1935). Other varieties with different coloured foliage have been introduced into culture (Saquet, 1996). Hibiscus tiliaceus L. has its origin in the Pacific Islands (Konczak, 1996).
Morphologic description of Hibiscus L.
Herbs, shrubs or trees. Flowers axially. Calyx 5-lobed. Five petals united at the base with the staminal column. Ovulary 5-locular each with 3 or more ovules. Fruit a 5-valved capsule (Brown, 1935).
Morphologic description of Hibiscus tiliaceus L.
Trees up to about 10 m in height. Young stems grayish-puberulent. Leaf blades orbicular- ovate, about 8-30 cm in diameter, simple or slightly 3-lobed, entire or entire varying to dentate. Leaf blade palmately 7-9-veined, the 3 central veins glauduliferous at the base. Leaf blade beneath densely to thinly pubescent, grayish-white to light green and subglabrous above. Petioles puberulent and about 2-15 cm long. Pentacles from the distal axis, about 2-10 cm in length, puberulent and bearing 1 or more flowers. Flowers cup-shaped. Petals broadly obovate, about 7 cm long and yellow, but purple at the base (Brown, 1935). The flowers gradually turning red with age and falls at sunset (Hargreaves and Hargreaves, 1970, Konczak, 1996). Calyx lobes are lanceolate, 2,5 cm in length and puberulent. Capsule 2,5 cm in diameter, pubescent and 5-valved. Seeds reniformed and about 5 mm in length (Brown, 1935).
Hibiscus tiliaceus L. var. typicus
Trees up to 7 m in height. The trunk is about 40 cm in diameter with moderately furrowed bark. Leaf blades about 15 cm in length, simple, entire, grayish-white and densely puberulent beneath (Brown, 1935).
Hibiscus tiliaceus L. var. henryanus F. Brown.
Trees up to about 13 m in height. The trunk erect and about 40-150 cm in diameter. The trunk is larger, more erected and less branched in the lower portion than var. typicus. The bark is gray and deeply furrowed. Leaf blade up to 30 cm in length, simple varying to slightly 3- lobed. Leaf beneath varying from densely pubescent and gray to thinly pubescent and light- green. Leaf margin varying from entire to obtusely dentate (Brown, 1935).
Hibiscus tiliaceus L. var. sterilis F. Brown.
Shoots dimorphic with fertile and sterile shoots. Fertile and sterile shoots are commonly produced on separated trees. Fertile shoots resembling those of var. typicus, but more erect, the large ones up to 20 m in heights and 10-40 cm in diameter. The bark coarsely and deeply furrowed. Heartwood light yellowish-brown, softer and not as heavy as in var. henryanus. Leaves entire to dentate. Flowers persistent yellow with dark-maroon centers or turning reddish-yellow with age (Brown, 1935).
Sterile shoots, commonly 5-20 m in height and 10-100 cm in diameter. Young stems pube scent. Bark of older stems thick and furrowed. Leaf blades small, about 8x6 cm, but ranging from 4-20 cm in length. Leaf blades obtusely to acutely dentate and beneath thinly pubescent and light-green. Heartwood blackish-brown and very hard. Sterile (Brown, 1935).
Habitats
Hibiscus tiliaceus L. is common to abundant in littoral forests and mangrove forest margins of atolls and high islands. It is also one of the most common secondary forest trees and is frequent in disturbed forests (Whistler, 1980). The species is found on islands and coasts all over the Tropical Pacific (Whistler, 1980; Chin & Enoch, 1988). In Tahiti it is a very common tree both by the shore, in the forests, valleys and on mountain slopes (Konczak, 1996), but it is rarely found in altitude above 800 m (Brown, 1935; Saquet, 1996).
Hibiscus tiliaceus L. var. typicus
The trees are very common in valleys (Brown, 1935; Saquet, 1996) where they make impassable brushwood with their characteristic branches in all directions. The trees can be found from the shore up to 800 m altitude (Saquet, 1996).
Hibiscus tiliaceus L. var. henryanus F. Brown
The trees grow well in poor, salty soil at the seashore (Konczak, 1996). It is very common by the shore, but it can also be found up to 800 m altitude (Brown, 1935).
Hibiscus tiliaceus L. var. sterilis F. Brown.
The tree grows on dry slopes, shallowed ravines of the upland and in the valleys (Brown, 1935). This varity is often seen in culture (Petard, 1986).
Use in cultivation
The tree grows well inland. It is not too dense and gives light shade. It is a good tree for planting near pathways, in small gardens or as a screen. It flowers almost continuously and seeds are produced abundantly. The tree is propagated by seeds and the seeds are easy to germinate. The crown can be kept to a suitable size by pruning (Chin & Enoch, 1988; Holtum & Enoch, 1995).
Ancient use
Hibiscus tiliaceus L. was one of the most useful tree in Polynesia. The young bark with its strong bast fibers was peeled into long, narrow strips and twisted to robes. The robes were very strong whatever they were plaited or not (Brown, 1935; Chabouis & Chabouis, 1971). A line made of the bast was used with a bamboo hook to catch eels (Brown, 1935) and bark cut into strips was used to attach fish by the gills (Wheeler & Carillet, 1997). Of the adult bark "tapa" and "more" were made (Chabouis & Chabouis, 1971). "Tapa" is bark beaten thin and was the traditional clothing in pre-European Polynesia. "More" is fibre skits worn in traditional women's dances (Wheeler & Carillet, 1997). The light and strong wood, but soft and easy worked has been used for a numerous of purposes (Brown, 1935; Chabouis & Chabouis, 1971; Konczak, 1996). The wood has for example been used to make house frames, boards, paddles and outrigger-canoes (Chabouis & Chabouis, 1971).
The large leaves were gathered and bound together by their long petioles and made into a flat crushion to wrap around the food to be cooked in the Tahitian oven - an earth oven. Under this cover the food was isolated from the oven's earth walls and was slowly cooked (Chabouis & Chabouis, 1971). The leaves were used as plates too (Brown, 1935).
The flowers were used medically for their emollient properties against bronchitis, hemorr hoids and tonsilitis and to heal abscesses (Brown, 1935; Petard, 1986; Chabouis & Chabouis, 1971; Konczak, 1996). The flowers were and are still used in head garlands (Hargreaves & Hargreaves, 1970).
Laws
Hibiscus tiliaceus L. in Tahiti is not protected neither by local protection, "The Washington Convention" nor export embargo. The seeds are therefore legal to collect and export (Vernaudon, 1997).
In Denmark Hibiscus tiliaceus L. comes under § 1 and appendix 5 in "The Proclamation about Import and Export of Plants". These are saying plants for planting have to be accompanied by a plant health certificate. The Minister of Agriculture can by application dispense from this for example plants to be used in research, breeding ect. Seeds of Hibi scus tiliaceus L. can be imported without any permission or certificates (Landbrugsmini steriet, 1993; Duelund, 1997).
Conclusion
Hibiscus tiliaceus L. is located in the coast, lower mountain and valley zone, but rarely in the mountain zone. Var. typicus is most common in the valleys where it makes brushwood, var. henryanus F. Brown in saline soil at the sea shore and var. sterilis F. Brown grows on dry slopes. The tree is easy to cultivate and is propagated by seeds. All part of the tree has been used for many purposes
Hibiscus tiliaceus L. is not protected in anyway in French Polynesia. Seeds of Hibiscus tiliaceus L. are legal to import to Denmark, but plants have to be accom panied by a plant health certificate.