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Pinus attenuata



Pinus attenuata - Knobcone pine, Narrowcone pine
  • Pinus attenuata - Knobcone pine, Narrowcone pine - Click to enlarge
  • Pinus attenuata cone - Click to enlarge
  • Pinus attenuata trees - Click to enlarge

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Weight1.5 kg
Height15 - 20 cm
PropagationGraft
RootstockPinus wallichiana

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Scientific name: Pinus attenuata  J.Lemmon  1892

Synonyms: Pinus californica Hartw., Pinus tuberculata Gordon, Pinus tuberculata var. acuta Mayr 

Common names: Knobcone pine, Narrowcone pine

 

Description

Tree to 25(-35) m tall, with trunk to 0.8(-1.1) m in diameter. Bark dark grayish brown, smooth and scaly above, divided below into irregular blocks by shallow, narrow furrows. Crown narrow, thin, and irregular, with branches horizontal to angled steeply upward and thinly to moderately thickly clothed with foliage at the tips. Twigs reddish brown, hairless. Buds 15-20 mm long, resinous. Needles in bundles of three, each needle (7-)9-18(-20) cm long, stiff and sometimes slightly twisted, lasting 4-5 years, yellowish green. Individual needles with lines of stomates on all three faces, a two-stranded midvein, and two to five resin canals deeply embedded in the leaf tissue at the outer corners and elsewhere. Sheath 10-20 mm long, persisting and falling with the bundle. Pollen cones 10-15 mm long, light reddish brown. Seed cones (8-)10-15 cm long, held flush to the stem, narrowly and pointedly egg-shaped, strongly asymmetric, with 75-150 or more seed scales, green before maturity, ripening light yellowish brown, remaining attached and closed for up to 20 years or more, opening after fires to release the seeds, on a stalk up to 1 cm long. Seed scales paddle-shaped, the exposed portion low and rounded on the side facing the shoot and near the tip, progressively larger and more pyramid-shaped toward the base on the outer side (hence the common name), with a thick, strong, clawlike umbo. Seed body 5-7 mm long, almost black, the easily detachable wing 12-20 mm long.

The scientific name (Latin for ‘tapering’) was chosen to describe both the seed cones and the shape of the crown.

Coast Rangers and Sierra Nevada of Pacific North America from southwestern Oregon, through California to northwestern Baja California (Mexico). In fire-prone shrublands (chaparral) on dry foothill slopes; 300-1,200(-1,700) m.

 

Conservation Status

Red List Category & Criteria: Least Concern

Pinus attenuata has an extensive extent of occurrence and is still numerous in certain parts of its range, especially in the northern counties of California. In certain areas close to urbanization fire prevention and suppression is likely to affect this species negatively in future, so a limited decline percentage is suspected for the future. However, this seems insufficient in relation to the global population size to place this species under threat or even to mark it as Near Threatened.

Numbers of mature trees in any given locality can fluctuate greatly with the incidence of fire, which tends to kill all trees. Regeneration from seeds normally follows this, and in the early stages seedlings and saplings can be numerous. However, this does not normally affect the global population, as these fires do not occur simultaneously everywhere, but are interspersed in space and time.

This species is a fire successional tree with extremely persistent and serotinous seed cones on dry slopes in chaparral or similar vegetation, also on rocky outcrops of serpentine with little other plant growth. In the northern part of its range, where trees grow somewhat taller, it is often mixed with several species of oak (Quercus spp.) and with Cupressus sp. In the U.S.A. its altitudinal range is from 300-1,200(-1,700) m a.s.l. In Mexico it is found mainly from 250-600 m a.s.l. and close to the coast. Phenology: Pinus attenuata disperses pollen in late March-April in most of its range.

Prevention of fire will eventually lead to the disappearance of this species from the forest community, which becomes then dominated by less fire-adapted tree species. Urbanization in many parts of its range is a potential threat that may lead to a decline in the near future.

Knobcone pine has little or no value as a timber tree. Its erratic growth habit and generally small size do not yield quality timber; its dry habitat ensures slow growth to any useful size, although on establishment after fire its initial growth rate is quite rapid. Cross sections of stems with inclosed whorls of cones have sometimes been polished and offered as curios in local woodcraft shops. Its horticultural merits are likewise not esteemed and it is therefore restricted to a few arboreta and pineta, mainly in regions with a suitable, Mediterranean type climate, or at least one with warm, dry summers and mild winters. In California, hybridization experiments have resulted in hybrids with Pinus radiata (known as Pinus × attenuradiata Stockwell & Righter) and with Pinus muricata. All three species belong to a group of pines informally known as the 'California closed-cone pines' that are closely related.

This species occurs in several protected areas. Its long-term survival is closely dependent on fire regimes; management should attempt at maintaining the frequency and intensity of fires as close as possible to the natural situation. Knobcone pine has apparently been planted in several localities in California, some of which are outside its natural area of occupancy or even extent of occurrence. It is doubtful whether these can be interpreted as “benign introductions” and they are not considered as part of this assessment.

 

Cultivars

Pinus attenuata ’Nana’                                     
Pinus attenuata ’Ralf’                                      
Pinus attenuata ’Sevcik’ 

 

References

  • Farjon, A. (2010). A Handbook of the World's Conifers. Koninklijke Brill, Leiden.
  • Eckenwalder, J.E. (2009) Conifers of the World: The Complete Reference. Timber Press, Portland.
  • IUCN Red List of Threatened Species, International Union for Conservation of Nature and Natural Resources. Cambridge, UK /Gland, Switzerland

Copyright © Aljos Farjon, James E. Eckenwalder, IUCN, Conifers Garden. All rights reserved.


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