The taxonomic boundary between Pinus ayacahuite Ehrenb. ex Schltdl. and Pinus strobiformis Engelm. has been interpreted differently among specialists in the taxonomy of pines. Some have tended to use a wider concept of P. ayacahuite and others a wider concept of P. strobiformis (to include P. ayacahuite var. veitchii for instance). The boundary is not clear and has traditionally been drawn based primarily on observed variation in the seed cones and the seeds. Genetically, it is likely that there is introgression between these two closely related species, but a geographical zone in which this possibly occurs has not been defined[].

Common Name: Mexican White Pine

General Information

Pinus ayacahuite is an evergreen tree usually growing 30 - 35 metres tall but with some specimens up to 55 metres[, ]. The large bole, which is often very tall and free of branches, can be up to 200cm in diameter[].
An important and highly sought after timber tree in Mexico and Mesoamerica where it is harvested on a large scale from the wild. The tree is also harvested from the wild for local use as a food, medicine and source of materials.
Whilst undoubtedly exploited for its timber, Pinus ayacahuite is widespread and common in many mountain forests, although becoming rare in the extreme south of its range. Logging has a negative impact in heavily exploited areas where the number of mature trees is declining. The plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2013)[].

Known Hazards

The wood, sawdust and resins from various species of pine can cause dermatitis in sensitive people[].

Botanical References

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Range

Central America - Honduras, El Salvador, Guatemala and Mexico

Habitat

An emergent tree in mixed montane conifer forest on mesic sites, or growing in groups or small groves[]. Rich, deep soils in sheltered valleys and mountain slopes; at elevations from 2,400 - 3,600 metres[, ].

Properties

Conservation Status	Least Concern
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Tree
Height	35.00 m
Growth Rate	Slow
Pollinators	Wind
Self-fertile	No
Cultivation Status	Wild

Cultivation Details

Pinus ayacahuite is unique in being the only tree from the tropics, where it is found at elevations from 1,800 - 3,100 metres between the latitudes of 14 - 20° north, to also succeed in central Scotland at a latitude of 57° north[, ]. It grows best in areas where annual daytime temperatures are within the range 17 - 24°c, but can tolerate 9 - 28°c[]. It can be killed by temperatures of -10°c or lower, with new growth being damaged at -1°c[]. It tolerates temperatures down to about -15°c[]. It prefers a mean annual rainfall in the range 1,500 - 2,000mm, but tolerates 1,200 - 2,500mm[]
Grows best in a sunny position on loamy, well drained soils[, ]. Thrives in a light well-drained sandy or gravelly loam[], though it is tolerant of various other soils[]. Dislikes poorly drained moorland soils[]. Prefers a pH in the range 4.5 - 6.5, tolerating 4 - 8[]. Established plants can tolerate up to 6 months of drought[].
Growth of older trees tends to be very slow but many younger trees are growing fairly quickly averaging more than 30cm a year[].
Annual wood production potential is 8 - 15 cubic metres per hectare[]..
The cones open and shed their seed whilst still attached to the tree[].
Plants are strongly outbreeding, self-fertilized seed usually grows poorly[]. They hybridize freely with other members of this genus[].
Seed cones are up to 30cm long[].
Leaf secretions inhibit the germination of seeds, thereby inhibiting the growth of other plants below the tree[].
Plants in this genus are notably susceptible to honey fungus[].

Edible Uses

Seed - raw or cooked[]. The seed is about 8mm long[]. Rich in oil, the seed has a resinous flavour.

A vanillin flavouring is obtained as a by-product of other resins that are released from the pulpwood[].

Medicinal

Oil of turpentine, obtained from the oleo-resin of all pine trees, is antiseptic, antispasmodic, astringent, diuretic, rubefacient, stimulant and vermifuge[, ]. It is a valuable remedy used internally in the treatment of kidney and bladder complaints and is used both internally and as a rub and steam bath in the treatment of rheumatic affections[]. It is also very beneficial to the respiratory system and so is useful in treating diseases of the mucous membranes and respiratory complaints such as coughs, colds, influenza and TB[].
Applied externally in the form of liniment plasters, poultices, herbal steam baths and inhalers, it is a very beneficial treatment for a variety of skin complaints, wounds, sores, burns, boils etc[].

Agroforestry Uses:

The needles contain a substance called terpene, this is released when rain washes over the needles and it has a negative effect on the germination of some plants, including wheat[].

Other Uses

A tan or green dye is obtained from the needles[].

Oleo-resins are present in the tissues of all species of pines, but these are often not present in sufficient quantity to make their extraction economically worthwhile[]. The resins are obtained by tapping the trunk, or by destructive distillation of the wood[, ]. In general, trees from warmer areas of distribution give the higher yields[].
Oil of Turpentine consists of an average of 20% of the oleo-resin[] and is separated by distillation[, ]. Turpentine has a wide range of uses including as a solvent for waxes etc, for thinning and dissolving varnish and paints, a shoe polish, medicinal etc[, ].
Rosin is also obtained by distillation of pine resin. This is used in paper glue and soap manufacturing, as a constituent of varnishes and paints, and for coating the bows of stringed musical instruments such as violins[, ].
Pitch can also be obtained from the resin and is used for waterproofing, as a wood preservative etc[].

The wood is used for construction, carpentry, furniture and utilities such as containers, pallets and crates as well as wood pulp[].

Propagation

It is best to sow the seed in individual pots as soon as it is ripe if this is possible. A short stratification of 6 weeks at 4°c can improve the germination of stored seed[]. Plant seedlings out into their permanent positions as soon as possible[]. Plants have a very sparse root system and the sooner they are planted into their permanent positions the better they will grow[]. Trees should be planted into their permanent positions when they are quite small, between 30 and 90cm[]. We actually plant them out when they are about 5 - 10cm tall. So long as they are given a very good weed-excluding mulch they establish very well[]. Larger trees will check badly and hardly put on any growth for several years. This also badly affects root development and wind resistance[].
Cuttings. This method only works when taken from very young trees less than 10 years old. Use single leaf fascicles with the base of the short shoot. Disbudding the shoots some weeks before taking the cuttings can help. Cuttings are normally slow to grow away[].

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