Pinus

• Authority

  Farjon, Aljos K. & Styles, Brian T. 1997. Pinus (Pinaceae). Fl. Neotrop. Monogr. 75: 1-291. (Published by NYBG Press)

• Family

  Pinaceae

• Scientific Name

  Pinus

• Type

  Lectotype species (vide Britton, N. Amer. Trees 5. 1908). Pinus sylvestris Linnaeus, Sp. Pl. 2: 1000. 1753.

• Synonyms

  Strobus, Caryopitys, Apinus, Leucopitys Nieuwl., Ducampopinus

• Description

  
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  Genus Description - Derivation: classical Latin name pinus. English pine, Spanish pino. Trees, or less commonly shrubs, evergreen, resinous in wood, bark, leaves, and often cones, aromatic; 1-75 m tall, diameter at breast height (dbh) 5-320 cm. Trunk monopodial, or shrubs in some species multistemmed, branching in pseudowhorls. Bark of older stems variously (deeply) furrowed or plated, to thin and scaly or thin and smooth, ridges and/or plates layered or scaly, more or less conspicuously exfoliating in often intricate patterns. Wood with normally conspicuous annual ring boundaries; resin ducts present or absent; ray tracheids present or absent, xylem parenchyma absent. Shoots dimorphic, with long shoots and dwarf shoots; long shoots uninodal or less commonly multinodal; dwarf shoots axillary to spirally arranged primary leaves (cataphylls). Cataphylls on long or short decurrent leaf bases (pulvini) on long shoots, non-chlorophyllous, enclosing "winter buds" (primordial long shoots or ovuliferous strobili), subtending dwarf shoot buds or pollen strobili, early deciduous or persistent. Secondary leaves (needles) borne in fascicles of (1-)2-5(-8) on dwarf shoots; the fascicles surrounded at base by an early deciduous or persistent sheath of bud scales or their remnants, persisting 2-30 years and falling as fascicles; length 2.5-50 cm, width 0.5-2.5(-7) mm, acicular (one species lanceolate), plano-convex or triangular (rarely terete or flat) in cross section, entire or serrulate; epistomatic or amphistomatic (one species occasionally hypostomatic); resin ducts (1-)2 to several, variously positioned in the mesophyll; vascular bundles single or double, enclosed in a stele. Pollen cones spirally arranged near the proximal end of new long shoots, ovoid-oblong to cylindrical; consisting of a thin axis with numerous spirally arranged, (sub-)peltate microsporophylls, each bearing two longitudinally dehiscent sporangia; pollen bisaccate. Seed cones (ovuliferous cones) subterminal or sometimes appearing to be lateral, borne singly or more commonly clustered, pedunculate, maturing in the second year or rarely in the third year, shed early or variously persistent, initially erect; mature cones pendulous or spreading, opening soon or variously serotinous, (obliquely) ovoid to cylindrical, 2-60 cm long. Seed scales (ovuliferous scales) persistent, obovate to oblong, thin or thick woody, attached to a slender to very thick axis; the exposed portion (apophysis) variously thickened and/or elongated; bearing in a terminal or dorsal (abaxial) position the remnant of the exposed portion (umbo) from the first year’s development, which may be terminated in a (deciduous) spine or prickle. Seeds obovoid, slightly flattened; seed coat thin or thick, without resin vesicles; seed with an adnate or articulate membranous wing derived from the adaxial part of the seed scale; several times larger than the seed and effective, or (greatly) reduced and in articulate wings remaining with the scale. Cotyledons 3-24, denticulate or entire. Chromosome number 2n = 24 (.v = 12).

• Discussion

  Distribution and Ecology: Mexico: In Guanajuato, Querétaro, Hidalgo, Veracruz, México, Puebla, Tlaxcala, Morelos, and Michoacán. Forming emergent trees in mixed montane conifer forest on mesic sites, or growing in groups or small groves. In much of its range it is more or less sympatric with var. ayacahuite and hybridization probably occurs. The high-altitude stands are subject to snowfall and frost in some winters. Its altitudinal range is (2000-)2500-32(K)(-3600) m.