Hartweg's Pine (Pinus hartwegii; syn. P. rudis, P. donnell-smithii) is a pine native to the mountains of Mexico and Central America east to Honduras. It is a very high altitude species, growing at altitudes of 2500-4300 m, and forms the alpine tree-line on most of Mexico's higher mountains. It is named after Karl Theodor Hartweg, who discovered it in 1838.

It is an evergreen tree reaching 20-30 m in height, with a broad, rounded crown. The bark is thick, dark grey-brown, and scaly or fissured. The leaves are needle-like, dark green, five (occasionally four) per fascicle, 10-20 cm long and 1.2-1.5 mm wide, the persistent fascicle sheath 1.5-2 cm long. The cones are ovoid, 6-13 cm long, black or very dark purple, opening when mature in spring to 5-7 cm broad. The seeds are winged, 5-6 mm long with a 1.5-2.5 cm wing. Pollination is in late spring, with the cones maturing 20-22 months after.

It is closely related to Montezuma Pine (P. montezumae), differing from it in the shorter leaves, black (not brown) and smaller cones; it replaces Montezuma Pine at high altitudes, and often hybridises with it where they meet at middle altitudes.

References

• Gymnosperm Database: Pinus hartwegii

Pinaceae