Digger pine

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Digger pine
Digger pines in the Sacramento Valley, California

Digger pines in the Sacramento Valley , California

Systematics
Order : Conifers (Coniferales)
Family : Pine family (Pinaceae)
Subfamily : Pinoideae
Genre : Pine ( Pinus )
Subgenus : Pinus
Type : Digger pine
Scientific name
Pinus sabiniana
Douglas ex D.Don

The Digger pine or Sabine's pine ( Pinus sabiniana ) is an evergreen conifer from the genus of the pines ( Pinus ) with usually threefold, 20 to 28 centimeter long needles and very large and heavy, 17 to 25 centimeter long seed cones. The natural range is in California . The species is classified as not endangered in the IUCN Red List . It is rarely used as a supplier of wood.

description

Appearance

The digger pine grows as an evergreen tree up to 25 meters high. The trunk grows straight or curved, as a monopodium or forked and reaches a diameter of 100 centimeters at chest height . The largest specimen measured in 1986 reached a height of 49 meters with a trunk diameter of 1.5 meters and a crown diameter of 24 meters. This tree no longer exists, the largest known specimen since then only reaches a height of 37 meters.

The trunk bark is thick, rough and scaly. It is divided into brownish gray to blackish gray, irregular, elongated plates, which are separated by reddish brown cracks. The main branches are long, horizontal or erect. The branches are often retained in the lower part of the trunk and do not fall off. The few higher-order branches form a broad, irregular and open crown. The branches can be both thin and thick. They are hairless, initially pale gray-brown and later darker brown, surrounded with a thin bluish layer of wax and only sparsely needled. They are rough due to protruding, run-down pulvini , remnants of fallen needle bundles.

Buds and needles

The buds are resinous, ovoid-conical and have a pointed end. Terminal buds are 15 to 25 millimeters long, lateral buds are smaller. The lower leaves growing around the buds are pressed, reddish brown with a paler edge. The needles grow in threes in a light brown needle sheath that is initially 20 millimeters long, but shortens to 5 to 7 millimeters. They are gray-green, protruding or hanging, flexible, slightly twisted along the longitudinal axis, usually 20 to 28 centimeters long, less often from 15 to 32 centimeters and 1.5 millimeters thick. The edge of the needle is finely sawn, the end pointy-piercing to awl-shaped . There are clear stomata lines on all sides of the needle . Usually two or three, less often up to ten resin canals are formed. The needles stay on the tree for three to four years.

Cones and seeds

The pollen cones are initially yellow and later turn orange-brown. Their shape is ovoid to ellipsoid and 10 to 15 millimeters long. The seed cones usually grow individually, rarely in pairs, at the base of new shoots on sturdy, 2 to 5 centimeter long stems. Fully grown cones are very large, very resinous, broadly ovoid and almost symmetrical. Open cones are 17 to 25 centimeters long with a diameter of 15 to 20 centimeters with a flat or more or less convex base. The 90 to 120 seed scales are thick, woody, stiff and dull brown. The apophysis is clearly defined, 20 millimeters wide, chocolate brown, sharply keeled across and suddenly or gradually changes into the umbo . This lies dorsally and is 10 to 20 millimeters long, at the base up to 12 millimeters wide, keeled on the side and ends in a sharp, hook-shaped spine .

The cones can weigh 300 to 600 grams and in exceptional cases even over 1 kilogram. They ripen after two years, then slowly open and stay on the tree for up to five more years. The seeds are narrow, obovate, somewhat flattened, 15 to 20 millimeters long, 7 to 10 millimeters wide, smooth and dark brown. The seed wings are short and wide and about 10 millimeters long.

Chromosome number

The number of chromosomes is 2n = 24.

  • Trunk bark

  • Pollen cones

  • Branches with seed cones

Distribution, ecology and endangerment

Distribution area of ​​the Digger pine
Digger pines in Pinnacles National Park

The natural range is in California in the western United States. Endangered stocks in Oregon are also noted. The Digger Pine grows in the mountains and foothills that surround California's long valley , from the edge of the Mojave Desert to the mountain slopes of the Pacific Ocean. You can find them at heights of 50 to 1800 meters. The distribution area is assigned to winter hardiness zone 8, where the mean annual minimum temperatures between −12.2 and −6.7 ° Celsius prevail. The climate is dry in summer, with annual rainfall varying greatly, ranging from 250 millimeters on the edge of the desert to 1780 millimeters in the Sierra Nevada .

Near the coast, the digger pine grows in the fire-prone chaparral together with heather ( Erica ) and similar species. On the lower slopes of the Sierra Nevada and the higher slopes of the coastal mountains you can find them with different oak species and often with the Coulter pine ( Pinus coulteri ), and in the north of the range with the West American juniper ( Juniperus occidentalis ). The digger pine mostly grows in open woodland, with individual trees protruding from a layer of bush, or in areas that are mostly overgrown with grasses and herbs. The heavy cones are used by various squirrels (Sciuridae) and jays as a source of food. The croissants get the cones from the trees and gnaw their way through the thick scales to get to the seeds. The jays play an important role in distributing the seeds.

The digger pine is attacked by the rust fungus Peridermium harknessii , which causes gall formation on the branches throughout the range , but does not cause serious damage. The dwarf mistletoe Arceuthobium occidentale particularly attacks trees in loose forests and spreads very quickly. Infestation leads to growth losses, deformations and also to the death of trees. The roots are attacked by the common root sponge ( Heterobasidion annosum ), which hardly causes any damage in loose forests, but can spread quickly in plantations. Cones, twigs and needles are attacked by a wide variety of insects. The beetle Ips spinifer attacks the bark and often causes drought or fire weakened trees to die. The increased production of resin can repel beetles, for some the resin fumes are also toxic. However, the resin attracts the curler Petrova sabiniana , which pupates in the resin. The seeds are protected from insects by their shell, but a large proportion of the seeds are eaten by rodents and birds.

In the Red List of the IUCN is Pinus sabiniana classified as endangered ( "Lower Risk / least concern"). However, it should be noted that a reassessment is necessary.

Systematics and research history

The digger pine ( Pinus sabiniana ) is a species from the genus of the pines ( Pinus ), in which it is assigned to the subgenus Pinus , section Trifoliae and subsection Ponderosae . It was first discovered in 1826 by David Douglas in the area of ​​the Umpqua , an Indian tribe living in southern Oregon , but he lost the samples while crossing the Santiam River . He did not find the species until 1831 on a trip through the Gabilan Mountains . In 1832 the species was first described scientifically by David Don in Description of the Genus Pinus , taking the description of David Douglas literally.

The generic name Pinus was already used by the Romans for several types of pine. The specific epithet sabiniana could refer to Joseph Sabine (1770-1837), a tax clerk and secretary of the Horticultural Society , who promoted Douglas' collecting activities. The name could, however, also honor his younger brother Edward Sabine (1788-1883), the former President of the Royal Society . Sometimes the type epithet is also written sabineana .

The Digger pine forms hybrids with other Pinus species with great difficulty : Only one attempt at hybridization with the Coulter pine was successful (status 2010). In contrast, there were several successful hybridization attempts with Pinus torreyana . In contrast to the Coulter pine, no hybridization with Jeffrey's pine ( Pinus jeffreyi ) or any other species of the Ponderosae subsection was successful .

use

The Digger pine is of little economic importance due to its irregular growth and high resin content. The wood is used to make railway sleepers , pallets and wood chips . The digger pine is rarely seen as an ornamental tree : it is rarely found in arboretums and pine trees in areas with a suitable climate, such as in England, western France, the Mediterranean and Australia.

The indigenous population used the seeds as food and the resin both to make drums and to seal baskets. The nutritional value of the seeds is comparable to that of other edible pine kernels, but the seeds are hardly used economically. Oils and turpentine are extracted from the twigs and needles .

swell

literature

  • Aljos Farjon: A Handbook of the World's Conifers . tape 2 . Brill, Leiden-Boston 2010, ISBN 90-04-17718-3 , pp. 756-757 .
  • James E. Eckenwalder: Conifers of the World. The Complete Reference . Timber Press, Portland, OR / London 2009, ISBN 978-0-88192-974-4 , pp. 476 .
  • Andreas Roloff , Andreas Bärtels: Flora of the woods. Purpose, properties and use. With a winter key from Bernd Schulz. 3rd, corrected edition. Eugen Ulmer, Stuttgart (Hohenheim) 2008, ISBN 978-3-8001-5614-6 , p. 775.
  • Russell H. Burns: Silvics of North America . tape 1 conifers. United States Government Printing, 1991, ISBN 978-0-16-027145-8 .
  • Flora of North America Editorial Committee (Ed.): Flora of North America North of Mexico . Volume 2: Pteridophytes and Gymnosperms . Oxford University Press, New York / Oxford a. a. 1993, ISBN 0-19-508242-7 (English).
  • Helmut Genaust: Etymological dictionary of botanical plant names. 3rd, completely revised and expanded edition. Nikol, Hamburg 2005, ISBN 3-937872-16-7 , p. 487 (reprint from 1996).

Individual evidence

  1. ↑ a b c d Aljos Farjon: A Handbook of the World's Conifers , Volume 2, p. 756
  2. ↑ a b c d e f g h i James E. Eckenwalder: Conifers of the World , p. 476
  3. ↑ Roloff, Bärtels: Flora of the Woods , p. 775
  4. ^ A b Aljos Farjon: A Handbook of the World's Conifers , Volume 2, pp. 756-757
  5. ^ A b Robert Kral: Pinus sabineana in Flora of North America , Volume 2
  6. ↑ a b Pinus sabiniana in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved June 1, 2013.
  7. ↑ Pinus sabiniana. In: NatureServe Explorer. NatureServe, October 2012, accessed June 13, 2013 .
  8. ↑ a b c Aljos Farjon: A Handbook of the World's Conifers , Volume 2, p. 757
  9. ^ Burns: Silvics of North America , Volume 1, Conifers
  10. ↑ a b Pinus sabiniana in the endangered Red List species the IUCN 2012. Posted by: Conifer Specialist Group, 1998. Accessed June 1, 2013.
  11. ↑ a b Christopher J. Earle: Pinus sabiniana. In: The Gymnosperm Database. www.conifers.org, November 23, 2012, accessed June 2, 2013 .
  12. ↑ Pinus sabiniana. In: The International Plant Name Index. Retrieved June 2, 2013 .
  13. ↑ Exactly: Etymological dictionary of botanical plant names p. 487

Web links

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This version was added to the list of articles worth reading on June 17, 2013 .