Pinus jeffreyi Grev. & Balf.

  • 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 jeffreyi Grev. & Balf.

  • Type

    Type. United States. California: Shasta Valley, ( Chastey Valley, Lat. 41°30 N ), 24 Oct 1852, Jeffrey 731 (holotype, E; a poor specimen with 4 leaf fascicles, a bud and a broken seed and a few seed wings). [Epitype: United States. California: Trinity Co., Scott Mt., 2 Sep 1958, Alava et al. 2439A (E), here designated].

  • Synonyms

    Pinus ponderosa var. jeffreyi (Grev. & Balf.) Vasey, Pinus deflexa Torr., Pinus jeffreyi var. deflexa (Torr.) Lemmon, Pinus jeffreyi var. bajacalifornica Silba

  • Description

    Species Description - Tree, medium to large, height to 20-30 m, dbh to 100 cm. Trunk monopodial, straight, terete. Bark thick, rough and scaly, divided by deep, longitudinal and anastomosing fissures into thick, elongated plates, light buff to light brown, the fissures dark grey-brown, on young trees and branches rough and scaly, orange-brown. Branches of first order long, slender, spreading horizontally or assurgent at the ends, persistent; branches of higher orders sparse, curved or assurgent, forming an open pyramidal or flat-topped crown. Shoots stout, assurgent, very rough and scaly with persistent, decurrent pulvini, light orange-brown, often glaucous. Cataphylls large, ca. 20 mm long, triangular-subulate, reflexed, scarious, with erose-ciliate margins, light brown, weathering greyish black. Vegetative buds ovoid-acute or subglobose, the terminal buds 15-20 mm long, the laterals smaller, not resinous; the scales imbricate, subulate, with free apices and ciliate, white margins, light orange-brown. Fascicle sheaths of young leaves 20-25 mm long, with 8-10 pale orange-brown, imbricate scales, persistent but reduced to 10-15 mm in older fascicles, weathering grey-brown to blackish. Leaves in fascicles of 3, sometimes a few fascicles of 2, in dense, spreading tufts on thick branchlets, persisting (3-)4-5(-6) years, thick, rigid, straight or slightly curved, sometimes twisted, (12-)15-22(-25) cm X 1.5-1.9(-2) mm, with serrulate margins, acute-pungent to acuminate, light yellowish green to greyish green. Stomata on all faces of leaves, in 711 grooved lines on the convex abaxial face, in 3-5 conspicuous lines on each adaxial face. Leaf anatomy: Cross section transverse-triangular, with a convex abaxial side; epidermis thick; hypodermis multilayered, slightly intruding into the mesophyll; resin ducts (2-)3-5, medial, the three marginal ducts larger than any subsidiary ducts; stele oval in cross section; the outer walls of endodermal cells thickened; vascular bundles 2, distinctly separated. Pollen cones densely clustered near the proximal end of a new shoot, subtended by subulate bracts, ovoid-oblong to cylindrical, 20-35 X 6-7 mm, yellow or purplish yellow, maturing light brown. Seed cones subterminal, solitary or in pairs on short, stout, persistent peduncles, spreading and seemingly sessile at maturity, leaving a few basal scales on the branch when falling. Immature cones broadly ovoid, ca. 30 X 20 mm, with spreading spines, purplish, soon light brown, maturing in two seasons (16-18 months). Mature cones broadly ovoid to subglobose, with a slightly oblique, flattened base, (10-) 12-17 X 9-14 cm when open. Seed scales ca. 150-175, in a low spiral, parting soon and wide, thin woody, straight or slightly curved, up to 20 mm wide, light or dark brown abaxially, with distinct, lighter marks of seed wings on the adaxial side. Apophysis slightly raised, transversely keeled, broadly rhombic in outline, on the proximal scales more gibbous, often resinous, ochraceous to light brown. Umbo dorsal, moderately raised, transversely keeled, terminating in a distinct, curved, 3-5 mm long spine. Seeds obliquely ovoid, slightly flattened, 9-12 mm long, light yellowish brown with faintly darker spots. Seed wings articulate, effective, held to the seed by two thin claws, oblique, with a straight and a curved side, 20-25 X 10 mm, light yellowish brown to light brown. Number of cotyledons 7-13, usually 10. Remarks on morphology. The above description pertains to Pinus jeffreyi in Mexico only. Generally, both tree size and sizes of leaves and cones can be larger in the United States, especially in the Sierra Nevada of California. There trees up to 50 m or more occur, to which figures given by Martínez (1948) and Perry (1991) must be referring, although their books deal with Mexican pines. Similarly, cones in the Sierra Nevada can be up to 25-30 cm long, but we have not seen such large cones on our visits to the populations of this tree in Mexico. From more northern regions, the persistence of leaf fascicles is also reported (Bradshaw, 1941) to be longer, up to 8 years. The almost brick-red to red-brown bark seen by A. Farjon in parts of the Sierra Nevada has not been observed in the Mexican populations.

  • Discussion

    Uses. Although not an important timber tree in Mexico, its geographical isolation from other Mexican pine forests makes it of local or regional importance. Especially in the Sierra Juárez, exploitation may pose a threat to the limited and more scattered populations. Many of the stands in the Sierra San Pedro Martir are within a national park and reasonably well-protected.

    Pinus jeffreyi was found by the Scottish plant collector John Jeffrey in northern California, in Shasta Valley, on 24 October 1852. He had been sent out by the Committee of the Oregon Botanical Expedition, on behalf of its subscribers, to collect seeds of exotic plants. When the first batch of material finally arrived in Edinburgh in the summer of 1853, a list of its contents, including new species with descriptions, was published as a pamphlet (No. 8) “by order of the committee,” by its secretary, Andrew Murray. Although Murray (1853) ascribes the new conifer taxa to Balfour (who was the chair; Greville, often cited as co-author, did the illustrations), the authority with the new species is cited as “Oreg. Com.,” which has led to the interpretation that Murray, not Balfour, was the validating author (Farjon, 1993). This view is here revised in accordance with Art. 46.2 of the Tokyo Code (Greuter et al., 1994). The holotype, Jeffrey 731 (E), is such a poor specimen that use has been made of the new provision in the Code (Art. 9.7) to designate an epitype to accompany it.

    Formerly classified as a variety under P. ponderosa. more detailed research (Bradshaw, 1941; Johansen, 1953) has led to the now generally accepted view (e.g., Krai, 1993) that the two taxa are sufficiently distinct to be recognized as species. Intermediate forms have been recognized as natural hybrids (Haller, 1962), but these are infrequent. Under controlled conditions, crossability is relatively low (Bums & Honkala, 1990). As it has been established that P. ponderosa is absent from Baja California (Duffield & Cumming, 1949), no such hybrids are to be found there.

    The more or less disjunct populations in Baja California have been described by Silba (1990), on very narrow evidence, as P. jeffreyi var. baja-cal (fornica. His observation that the leaves are “mostly two per fascicle” is contradicted by the holotype specimen (I. L. Wiggins & Gillespie 4123, NY) and by all other material we have seen in and from Baja California, in which only an occasional fascicle has 2 leaves. Also are the leaves not wider than in specimens from California. Cone size appears to be smaller on average, but this character is of little taxonomic value (Duffield & Cumming, 1949). Vidakovic (1991) mentions a variety “peninsularis” from Baja California with “darker grey and deeply furrowed bark” but does not cite a valid publication of this name.

    Distribution and Ecology: United States: Primarily in California, extending into SW Oregon and extreme W Nevada; its main distribution is in the Sierra Nevada; there are disjunct populations on mountains in S California. Mexico: In Baja California Norte, scattered in the Sierra Juárez, but more common in the northern part of the Sierra San Pedro Martir, where it reaches its southernmost limit at ca. 30°40'N. Its altitudinal range in the Sierra Juárez is (1100-) 1400-1800 m; in the Sierra San Pedro Martir it occurs considerably higher, 1800-2500(-2700) m. Here it forms an open, mixed coniferous forest with other conifers. Common are also Abies concolor, Pinus lambertiana, and P contorta var. murrayana in the upper zone. In the Sierra Juárez it is often associated with Quercus spp. Both mountain ranges are granitic and provide acid soils. Annual precipitation is moderate, up to 500 mm, of which about half comes as winter snow at the higher altitudes. Phenology: Pollen is dispersed in June-July, depending on altitude and related climatic circumstances.

  • Distribution

    Mexico North America| Baja California Mexico North America|