Pinus patula
(Mexican weeping pine)

Preferred Scientific Name

• Pinus patula Schiede ex Schltdl. & Cham.

Preferred Common Name

• Mexican weeping pine

Variety

• Pinus patula var. longipedunculata Loock ex Martínez
• Pinus patula var. patula

Other Scientific Names

• Pinus patula var. macrocarpa M. T. Masters

International Common Names

• English: patula pine; spreading-leaved pine
• Spanish: ocote; pino chino; pino patula
• French: pin argente

Local Common Names

• Brazil: pinheiro
• Germany: Kiefer, Ausgebreitete; Kiefer, Mexikanische
• Mexico: ocote

EPPO code

• PIUPT (Pinus patula)

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Gymnospermae
•                 Class: Pinopsida
•                     Family: Pinaceae
•                         Genus: Pinus
•                             Species: Pinus patula

The genus Pinus, with over 100 species, is a taxon found almost exclusively in the northern hemisphere. The taxon is also notable among the Coniferae because it has its greatest diversity in Mexico and the western USA, rather than in China and Japan where most of the diversity of the remainder of the family Pinaceae is concentrated (Farjon, 1998).

Habit and size

In its native range, P. patula is said to be a graceful tree, height 12-20 (30 m or occasionally to 30-40 m) with d.b.h. up to 120 cm. In plantations outside its native range, tree heights of between 35 and 50 m have been recorded, at ages ranging from 20 years to 50 years (Loock, 1950; Styles et al., 1975).

The crown shape usually depends on both spacing as well as inherent variability of the trees. Open grown trees tend to have spreading crowns while closely spaced trees tend to have narrow crowns with good suppression of lower branches which subsequently die. Some trees will still have deep narrow crowns even when growing in the open. Although branching is said to be irregularly placed on the stem (Loock, 1950), in exotic environments branching tends to be regular with on average four branches per whorl, but the distance between whorls is variable. Foxtailing occasionally occurs but the majority of trees tend to be multi nodal with average distance between whorls of about 0.4 m. Within the native distribution range, branches have been reported to be pendent whereas in exotic environments, particularly Africa, the branches are borne at an angle above the horizontal. Branch size is very variable from fine branching to very thick branches.

Stem form

Stem form in P. patula is also very variable. Although atrociously crooked trees can be found in this species, stem form is generally moderate to good. Good specimen trees with straight cylindrical stems that retain apical dominance to the age of 30 years or more are quite common. Common defects include forking, sometimes caused by mechanical damage such as bird perching, butt sweep, bow, sinuosity and nodal swellings; such stem features are usually found in trees growing in warm lower altitude environments.

Bark

Bark is thick, rough and scaly with large elongated plates and deep, longitudinal fissures especially on the lower part of the bole, bark colour is dark grey-brown on lower trunk, and higher up and on younger trees bark is reddish-brown or orange, thin and papery (Vidakovic, 1991). The age at which mature bark appears is not yet known, but appears to vary with site. Some trees have been observed to develop completely smooth bark at lower, drier altitudes.

Crown

The crown may be rounded or spire-like with needles borne on pendent secondary branches. Branching may be from the ground. Young shoots are more noded, glaucous green, becoming reddish-brown in the second year.

Foliage

Buds cylindrical, 15-25 mm long, covered with long pointed, fringed scales, which are not resinous and spreading at the tips. Needles are borne in fascicles of 4 (may be 3 or 5), in drooping or spreading tufts, 15 to 30 cm long, very thin, and of a shiny light to yellowish-green in colour. Stomata lines on all needle surfaces; resin ducts 2-3, usually medial, sheaths slender, persistent, 10-25 mm long. Needles may persist for two to three years.

Inflorescences, flowers and fruit

Flowering in P. patula varies from site to site. In its native range, pollen shedding begins in January and lasts until April and wide tree to tree variation is observed. In Malawi, Zimbabwe and South Africa, flowering (both male and female flowers) occurs in spring, i.e., August to October. A secondary flush of only female flowers usually occurs earlier in the year (Barnes and Mullin, 1974; Drew, 1969). In Kenya which is very close to the equator, two flushes of both flowers occur coinciding with the two rainy seasons (April-May and October-November). Female flowers have also been recorded throughout the year. In Zimbabwe, studies showed that synchronisation of pollen shedding with female receptivity is good at altitude 1500 m, whereas pollen rain became progressively later at lower altitudes.

Cones

Conelets are usually lateral, rarely subterminal, persistent, somewhat oblong, ovate-conical, curved, oblique at base, tapering towards apex, sessile, rarely subsessile, single or in clusters of 2-5, up to 10 or even more. Cone size 4-9 cm long, pale brown, hard, strong, scales oblong with raised apophyses on which there is a minute prickle. Seed triangular, grey mottled with black, 5 mm long, wing 12-18 mm long (Vidakovic, 1991; Loock, 1950).

Observations on lack of natural regeneration at lower altitudes in Zimbabwe appear to indicate that at lower altitudes seed is probably empty (infertile); at higher altitudes natural regeneration occurs. Cones, which usually take two years to mature, are harvested in September-October.

P. patula flowers as early as age 2 years with female flowers appearing first and male flowers appearing in the fourth year. Five-year old trees produce viable seeds and cone and seed production is prolific by the eighth to the tenth-year.

Soil drainage

• free

Soil reaction

• acid
• neutral

Soil texture

• heavy
• light
• medium

Special soil tolerances

• infertile
• shallow