Rain tree
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Rain tree ( Samanea saman ) |
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| ( Jacq. ) Merr. |
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The rain tree ( Samanea saman ) is a plant species within the subfamily of the mimosa family (Mimosoideae). It is widespread in the northern Neotropic and is one of the best-known tree species in its homeland. The origin of his common name rain tree, Spanish Árbol de la lluvia , can no longer be clearly determined.
At night it seems to rain lightly under its crown and under the tree the grass stays green much longer in the dry season. The cause is assumed to be the excretions of singing cicadas, which inhabit the tree in great abundance. Or the extra-floral nectaries excrete sugar-rich juice that sometimes falls from the tree like rain. Another explanation of its name is the peculiarity of the rain tree to fold up its leaflets when it rains so that the water droplets hardly fall through the crown. During the flowering period, abundant stamens fall from the tree top like a shower from time to time. In connection with the shadow effect of the crown, the grass under the tree always stays green.
Description and ecology
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Vegetative characteristics
The rain tree grows as a tree with a widely spreading crown and, when standing alone, typically reaches a height of 17 to 24 meters, a trunk diameter of 40 to 120 centimeters ( BHD ) and a crown diameter of 30 meters. Trees standing close together can reach heights of 40 meters or more, but have smaller crowns. Compared to the wide, umbrella-shaped crown, the strong and straight trunk usually looks short. Maximum values have been described for a tree over 100 years old in Trinidad , which reached a height of 50 meters, a trunk diameter of 2.6 meters and a 60 meter wide crown. A 60-meter-high tree with an 80-meter-wide crown was used for a tree house in the Walt Disney film Swiss Family Robinson and there should have been even larger ones, as Humboldt described.
The bark is grayish to gray-brown, still smooth on the young tree, later rough and cracked to more or less scaly and flaky. The inner bark is colored light brown to gray-pink. The tree has deep roots in dry locations, and an extremely shallow root system is formed on moist soils.
The tree carries a yellowish rubber .
The rain tree is evergreen in the tropical rainforests , but in dry forests it loses its leaves during the dry season and can be leafless for up to two months. The stalked leaves are double-pinnate and arranged alternately. The fine-haired, 4–8 cm long petiole has a 1st order pulvinus at the base. The leaves are 10 to 37 centimeters long, have a green, finely ribbed, hairy spindle ( rachis ) and form 3 to 9 pairs of stalked plumage of the 1st order with Pulvini 2nd order. The 6–13 cm long lateral leaflets, with a runny and hairy "Rhachis 2nd order" have 3 to 9 pairs and 2.5 to 6 cm long and 1.2 to 2.7 cm wide leaflets with 3rd order pulvini. The mostly almost sessile, bald, leathery leaves have entire margins , asymmetrically rhombic and have a mostly rounded, sometimes finely spiked tip. The top is a slightly darker green than the finely hairy underside. Nectaries are present on the leaves (rachis, petiole and pinna). The stipules are sloping. Meticulous and sloping "paraphyllidia" can occur on the pulvini of the feathers.
A special feature of the rain tree is the nightly folding of the opposite plumage and leaves, which also occurs in rainy weather or overcast skies. This nyctinastic sleeping position begins about 1 hour before sunset, and the normal position is resumed shortly before sunrise.
Inflorescence and flower
The main flowering time is in May and June. Green individually to, hairy and thickish 5 to 9 centimeters long Blütenstandsschäfte standing delicate, inflorescences are tassel-like at a height of about 3.5 centimeters and a diameter of about 6 centimeters, head-shaped and contain numerous (15-22) flowers, brush flowers . There are different cover sheets available. The hermaphrodite, stalked to sessile flowers are usually five-fold with a double flower envelope and somewhat dimorphic. The central, seated flower is somewhat larger, wider, up to 5–8 counters, with many more and longer tubular stamens and it produces nectar but no fruit. The peripheral, smaller and stalked flowers do not produce nectar to attract pollinators. The mostly five green, finely haired sepals are fused into an approximately 0.6–1 centimeter long, funnel-shaped tube that ends in five small calyx teeth. The usually five reddish, sometimes slightly fine-haired petals are fused into a 1–1.4 centimeter long tube with smaller tips. The approximately (20–30) or 50–80 in the central flower, filamentous and long stamens are about 3.5–4 inches long, white below and bright red above. The stamens of the peripheral flowers are briefly fused with the petals at their base (stemonozon). The anthers are small and heady. The upper permanent stamp consists of a single carpel of one to about 4 centimeters long, thread-like stylus having a small capitate or leaking and porous scar .
Fruit and seeds
When ripe, the legumes, brown to blackish, pointed and stiff-leathery, somewhat constricted at the seeds and with thick seams, are 7 to 21 centimeters long, 1.5 to 2.3 centimeters wide and about 0.6 centimeters thick, straight or light curved. They do not open on the tree and contain 5 to 25 segmented seeds and usually appear individually or in pairs on the heads. They often stay on the tree for a long time. The red-brown, flattened, smooth and 0.9–1.4 cm long, brittle-leathery, ellipsoidal to round seeds are embedded in a brownish, dry, sticky and sweet pulp. You are with a U-shaped pleurogram. The thousand grain mass is around 135 to 225 grams.
Most of the fruits remain under the mother tree, weather during the rainy season and thus release the seeds. Sometimes fruits are carried away by rodents or eaten by tapirs , which excrete the seeds undigested. Cattle, pigs, goats and sheep and, less often, horses eat the fruit in pastures. It is believed that the seeds were originally distributed by large mammal species that became extinct in the Pleistocene . Today this often happens through grazing animals.
Other features
The rain tree sprouts epigeously. The hypocotyl grows straight, is up to 10 centimeters long and has two short-stemmed, elliptical cotyledons. The primary leaves are opposite or almost opposite.
The number of chromosomes is 2n = 26.
Possible confusion
The rain tree is seldom confused with other species due to its large, umbrella-shaped crown, its leaves that fold up at night, the shape of the flowers and also the fruit pods filled with fruit pulp. In Hawaii this sometimes happens with Pseudosamanea guachapele during flowering, young trees resemble the species Albizia lebbeck .
ecology
Pollination is carried out by moths , but the rain tree is often flown to by bees as a source of nectar. According to other sources, bees are the main pollinators.
The rain tree can bind nitrogen through symbiosis with nodule bacteria of the genus Bradyrhizobium . In pastures , the growth of grass under and next to the tree is promoted by the enrichment of nitrogen compounds.
The rain tree is hardly endangered by animal or vegetable pests. In the Philippines the seedlings are attacked by the mildew species Erysiphe communis , in Hawaii the caterpillars of the butterfly species Melipotis indomita cause damage. In Puerto Rico , scale ants of the species Myrmelachista ramulorum drill into the shoots and lead to leaf losses. However, several types of beetles, flies, and butterflies usually damage or destroy 50 to 75% of the seeds.
Distribution and location requirements
The natural range extends from the Yucatan in Mexico via Guatemala to Peru , Bolivia and Brazil . However, the main distribution areas are Venezuela and Colombia . Due to its shadowy, huge and wide spreading crown, it was naturalized in subtropical areas of America such as Florida and the West Indies , and also in tropical and subtropical areas of Asia and Africa; so since 1880 in southern India , in Burma or in the Philippines. In Africa you can find it in Nigeria or Uganda . The rain tree has existed in Hawaii since 1847.
Samanea saman thrives in tropical and warm-subtropical climates at altitudes between from sea level to 1100 meters. It thrives with annual rainfall between 640 and 3810 millimeters. It is sensitive to frost and shade and is damaged by salt water spray. It can withstand high air temperatures in southern India with maxima of up to 47.5 ° C and drought of two to six months. The rain tree grows best on deep, moist, neutral or slightly acidic alluvial soil. It tolerates moderately salty soils and short-term floods.
Systematics
The specific epithet saman is derived from English zamang and is borrowed from an Indian language. According to another source, saman is a Spanish expression derived from a French dialect from the Caribbean and also means rain tree.
The taxonomic classification of the rain tree was interpreted very differently in the past. The synonym Pithecellobium saman Benth is often used in American literature . used. Further synonyms are Albizia saman F. Muell. , Calliandra saman Griseb. , Enterolobium saman Prain , Inga saman Willd. and Mimosa saman Jacq.
There are no subspecies and no cultivated forms. The appearance of the rain tree varies little in its area of distribution.
Further Samanea species are Samanea inopinata (Harms) Barneby & JWGrimes and Samanea tubulosa (Benth.) Barneby & JWGrimes u. a.
use
The rain tree is valued in tropical and subtropical areas as a shade-giving park and street tree. It was also used as a shade provider in coffee and cocoa plantations.
The fruits are used as fodder for cattle, goats and pigs on pastures.
The wood is relatively soft and of medium weight, has a yellowish sapwood and chocolate brown heartwood that turns golden brown and shows black stripes as it dries. In Hawaii, the beautiful wood is used to make handicrafts such as monkey pod bowles . The wood is seldom used for the production of furniture, as construction wood, for veneers or for heating.
The wood is also used in the construction of musical instruments (e.g. acoustic guitars from Washburn and Faith Guitars) under the name Monkey Pod and Trembesi . Here it is used for the top as well as for the body and the frame .
The sweet pulp is sometimes eaten by children, and drinks were also made from it in Mexico.
In Thailand , the rain tree serves as a main food source for the lac insect ( Kerria lacca ) that the starting product for shellac supplies
In novel and film
In the novel Raintree County (1948) by Ross Lockridge Jr. (* 1914, † 1948 by suicide ) and under the English title of the same name (1957), (German title: The land of the rain tree with Montgomery Clift and Elizabeth Taylor ) the tree plays an important role as the finder of the tree will understand the meaning of life .
literature
- Schütt, Weisgerber, Schuck, Lang, Stimm, Roloff: Trees of the tropics. Nikol, 2004, ISBN 3-933203-79-1 .
- The CABI Encyclopedia of Forest Trees. CABI, 2013, ISBN 978-1-78064-236-9 , p. 432 ff.
- Samanea saman at PROTA.
- Albizia saman at CABI Invasive Species Compendium.
Web links
- Samanea saman at NYBG.
- W. George Staples, R. Craig Elevitch: Samanea saman (rain tree). Ver. 2.1, April 2006, description at agroforestry.net, accessed on February 20, 2008, (PDF; Engl.)
- Samanea saman at Useful Tropical Plants.
- Albizia saman at Pitchandikulam Forest Virtual Herbarium (pictures).
Individual evidence
- ↑ a b c d Description from Reforestation, Nurseries and Genetics Resources (accessed February 29, 2008).
- ↑ ON Allen, Ethel K. Allen: The Leguminosae. Univ. of Wisconsin Press, 1981, ISBN 0-299-08400-0 , p. 590.
- ↑ Ruth L. Satter, Gordon T. Geballe, Arthur W. Galston: Potassium flux and leaf movement in Samanea saman. I. Rhythmic movement. In: The Journal of general physiology. 64 (4), 1974, pp. 413-430, doi: 10.1085 / jgp.64.4.413 .
- ↑ W. George Staples, R. Craig Elevitch: Samanea saman.
- ↑ Description in Tropicos, Flora de Nicaragua (Eng.)
- ↑ Schütt et al .: Trees of the Tropics
- ↑ Helmut Genaust: Etymological dictionary of botanical plant names. 3rd, completely revised and expanded edition. Birkhäuser, Basel / Boston / Berlin 1996, ISBN 3-7643-2390-6 (reprint ISBN 3-937872-16-7 ).
- ↑ Monkeypod on wood-database.com.
- ↑ Monkeypod on guitarbench.com.
- ↑ FAO: Non-Wood Forest Products in 15 Countries Of Tropical Asia: An Overview (accessed February 29, 2008).
