Desert ironwood
| Desert ironwood | ||||||||||||
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Desert ironwood ( Olneya tesota ) |
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Olneya | ||||||||||||
| A.Gray | ||||||||||||
| Scientific name of the species | ||||||||||||
| Olneya tesota | ||||||||||||
| A.Gray |
The desert ironwood ( Olneya tesota ) is the only plant species of the genus Olneya in the subfamily of the butterflies (Faboideae). The distribution area ranges from Arizona and California to the Mexican states of Baja California , Baja California Sur and Sonora .
description
The desert ironwood grows as a thorny shrub or tree and reaches heights of up to about 5–10 meters with trunk diameters of up to about 60 cm. In young plants the bark is gray and relatively smooth; in older trees it breaks open and becomes increasingly brownish and fibrous. On younger specimens or on side trunks, the trunk and the thicker branches are still thorny. This species is semi-evergreen , it loses its leaves when the temperature drops below about 2 ° C. If the drought persists, some of the leaves are thrown off to save water.
In the Sonora desert, the desert ironwood is one of the longest-lived trees; they can live up to 1500 years.
The alternate, short-stalked leaves are unpaired to paired pinnate and appear bluish-green due to the mostly fine, whitish hairs. The leaflet is about 5–10 cm long, with 9 to 17, rarely up to 25 leathery and obovate, lanceolate, entire, rounded to blunt, very short-stalked leaflets . They are each 0.7 to 2 cm long. One or two thorns up to 1 cm long grow at the base of each leaf.
The flowering period extends from May to June. The hermaphrodite flowers are zygomorph are fünfzählig double perianth (perianth). They are arranged in short, axillary and racemose inflorescences. The corolla has the typical structure of the butterfly flower with five petals . The cup-shaped, reddish-brown calyx and the flower stalks are hairy whitish. The boat is purple and the other petals white to pale pink. The ovary is hairy.
The legume, which is initially hairy, constricted and tipped at the seeds, is 4 to 8 cm long and brown and woody when ripe; it contains one to four or more round to ovate, somewhat flattened, dark brown, smooth, about 7-10 mm large and edible seeds.
Only fresh seeds can germinate without problems; older seeds must be stratified for germination .
ecology
At home, the canopy of a desert ironwood tree forms its own biotope. 230 different plant species have already been counted that germinate and thrive under the protection of the treetop. The seeds serve as food for several animal species (birds, rodents). Many insects live on the tree and attract birds and reptiles.
Distribution and location
The desert ironwood is native to the Sonoran Desert . Politically, the distribution area falls into the US states of Arizona (south and southwest), California (southeast) and the Mexican states of Baja California , Baja California Sur and Sonora . In Arizona the tree occurs at altitudes up to approx. 600 m; it is often found in dry river beds. The Ironwood Forest National Monument in Arizona was named after her.
Desert ironwood is sensitive to frost, mature trees die at −6 to −9 ° C. Desert ironwood can do well in extremely dry locations.
use
The wood is very hard and heavy ( ironwood ). It has a higher density than water and sinks to the bottom in the water. It is used, for example, in the manufacture of knife handles, as its hardness and toughness are ideal conditions for this application.
Machinability
Due to the high hardness of the wood, machining is difficult, but it is possible with tools for metalworking and with hard metal-tipped wood tools. Wood oils can be used as a final treatment, but due to the very dense structure, the wood absorbs only little oil slowly.
The seeds and the young fruits are edible.
literature
- C. Frank Brockman: Trees of North America. St. Martin's Press, New York 2001, ISBN 1-58238-092-9 .
- Forrest Shreve, Ira L. Wiggins: Vegetation and Flora of the Sonoran Desert. Volume 1, Stanford Univ. Press, 1964, ISBN 0-8047-0163-6 , p. 686.
Web links
- Olneya tesota at Useful Temperate Plants.
- Sonoran Desert Plants Olneya tesota at Cabeza Prieta Natural History Association (PDF; 13 MB at the bottom of the page).
- Datasheet at Desert Tropicals .
- Datasheet from College of Natural Resources and Environment - Virginia Tech .