Pinus quadrifolia Parl. ex Sudw.
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Authority
Farjon, Aljos K. & Styles, Brian T. 1997. Pinus (Pinaceae). Fl. Neotrop. Monogr. 75: 1-291. (Published by NYBG Press)
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Family
Pinaceae
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Scientific Name
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Synonyms
Pinus llaveana Torr., Pinus parryana Engelm., Pinus cembroides var. parryana (Engelm.) Voss, Pinus cembroides var. quadrifolia (Parl. ex Sudw.) Silba, Pinus juarezensis Lanner, Pinus cembroides var. juarezensis (Lanner) Silba
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Description
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Species Description - Tree, small and bushy, or a large shrub, height to 10-15 m, dbh to 30-50 cm. Trunk short, erect, low-branched or with a short, clear bole. Bark thick, rough and scaly, with deep lateral and longitudinal fissures, reddish brown, inner bark yellowish orange, outer bark weathering grey, on young trees and branches thin and smooth, reddish brown. Branches numerous, long, spreading or ascending, persistent; the higher-order branches slender, spreading or assurgent. Crown rounded, wide and open in old trees, more dense and regular ("beehived") in young trees. Shoots stout, rough with short decurrent pulvini. Cataphylls small, rigid, broad triangular, with erose margins, yellowish orange, soon grey and breaking off, leaving a small basal part. Vegetative buds ovoid-conical, the terminal bud 6-10 X 4-5 mm, the laterals acute, <8 mm long, orange-brown, slightly resinous; the scales imbricate, triangular, appressed but with free, acuminate apex and erose-hyaline margins. Fascicle sheaths initially 5-8 mm long, soon breaking up in recurving but early falling scales (not or rarely forming rosettes). Leaves in fascicles of (3-)4(-5), rarely a few fascicles 2 or 6; the fascicles often disintegrate partly before falling; remote on foliage branches, persisting (3-)4-7 years, spreading, curved or sometimes straight, rigid, often connivent for some time, (1.5-)2-4(-5) cm X (0.8-) 1-1.5(-1.7) mm, entire, acute-pungent, often with a partly exfoliating cutícula giving the margins an erose appearance, dull or lustrous grey-green to glaucous-green, with whitish stomatal bands. Stomata in two bands of 4-5 irregular lines on the adaxial faces, separated by a prominent midrib, rarely with a few stomata near the apex on the abaxial face. Leaf anatomy: Triangular in cross section; epidermis thick; hypodermis uniform, with 1-2, or locally 3 layers of cells towards the margins; resin ducts 2, rarely 1 or 3-4, external on the abaxial side; stele terete; the outer walls of the endodermal cells not thickened; vascular bundle 1, terete. Pollen cones crowded at the proximal end of new shoots in short clusters, subtended by triangular bracts, ovoid-globose to short cylindrical, ca. 10 mm long when shedding pollen, purplish red, turning yellowish. Microsporophylls subpeltate, with an incurvate distal part, smooth. Seed cones subterminal, solitary or in whorls of 2-4 on short, slender peduncles which fall with the cones. Immature cones globose, ca. 5 mm, with rhombic apophyses, yellowish green, soon yellowish brown, maturing in two years. Mature cones ovoid-globose to globose when closed, irregular when opened, often somewhat wider than long, more or less rounded at base, 4-6 X 4.5-7 cm when open. Seed scales ca. 30-50, only the central 6-12 fertile, parting widely, spreading but not reflexed, moveable, irregular, concavo-convex, with 1-2 deep seed cavities bordered by thin remnants of vestigial seed wings (1 seed often aborts), ochraceous to light or dark brown. Apophysis thick woody, raised, pyramidal or obtuse conical, transversely keeled, up to 10 (-15?) X 20 mm, recurved or straight, ochraceous to yellowish brown or reddish brown, often resinous. Umbo dorsal, flat or obtuse-pyramidal, rhombic in outline, up to 10 mm wide, centrally indented, concolorous with apophysis or lighter, often resinous. Seeds obliquely obovoid or elliptic, slightly flattened on one side, 12-18 X 8-12 mm, integument thin (0.3-0.5 mm), greyish brown to grey, macrogametophyte ("endosperm") white. Seed wings rudimentary on the scale, absent from the developed, free seed. Cotyledons 6-8.
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Discussion
Uses. There is no use of this species for timber. It is locally used for firewood. The seeds are edible and are harvested to be sold in local markets. Resin may be tapped on a small scale as well.
During the Mexican Boundary Survey by the U.S. Army under direction of Major W. H. Emory in 1850, C. C. Parry collected a new species of Pinus in the “mountains east of San Diego” which was called P. quadrifolia by Parry (msc.) and cited in synonymy under P. parryana Engelmann by Parlatore (1868). Pinus parryana Engelmann is a later homonym of P. parryana G. Gordon & Glendinning, which is a synonym of P. ponderosa. Engelmann (1862) based his description on the same collection made by Parry. Likewise, Torrey (1858) had used a later homonym, P. llaveana, to name Parry’s pine. Sudworth (1897) corrected these nomenclatural errors and took up Parry’s manuscript name for the correct binomial. The type collection has leaves in fascicles of 3-5, with ca. 15% in 3’s, 50% in 4’s, and 35% in 5’s (see also Lanner, 1974a).Lanner (1974a) studied several populations of Pinus quadrifolia in San Diego County, California, and in the Sierra Juárez, Baja California Norte. Based on his findings, of which he believed the number of leaves in a fascicle to be taxonomically the most informative character, he proposed a new species, P. suarezensis. It was described as a 5- (rarely 4-) leaved pinyon pine with 2 (rarely 1-3) resin ducts per leaf. Only a few trees remain among “populations” otherwise dominated by hybrids between P. monophylla and the new species; these putative hybrids were designated as P. X quadrifolia. Further evidence for this hypothesis was given in a (rather weak) correlation between mean resin duct number and mean leaf number, whereby 2-3-leaved fascicles had an average of 2-3 resin ducts and 3-5-leaved fascicles had 2. Using mean values to demonstrate the hybrid origin of individuals (multivariate intermediacy) seems to be the wrong approach to inferring hybridity (Wilson, 1992). Hybrid taxa are characterized by the coincidence of various parental and some intermediate character states, and in addition also by such which do not occur in a parental taxon (Rieseberg, 1995). Presenting data as mean values may show “overall intermediacy,” not character-bycharacter intermediacy in the samples (individuals). This is not to deny that some of the trees may be hybrids between P. monophylla and P. quadrifolia, as specimens with a consistently intermediate number of leaves (2-3) have been found (Lanner, 1974a: tables 1, 4), or that no introgression has taken place anywhere. On the other hand, fascicles of 5 leaves are present in various quantities on P. quadrifolia branches with 3-, 4-, and 5-leaved fascicles throughout its range. This character is extremely plastic, since it varies not only among trees in an apparent population, or on single trees, but also from year to year on a single branch as well (see also Lanner, 1974a).Apart from these considerations, the inference of hybridity of P. quadrifolia sensu Lanner (1974a) is based on a limited number of characters, of which leaf number and position of stomata appear to be intermediate only in trees with 2-3 leaves per fascicle. Back-crossing in diploid pines may, of course, obscure morphological intermediacy. The 2(-3)-leaved individuals at La Rumorosa, growing with P. monophylla and P. quadrifolia, were thought to represent Fl hybrids (Lanner, 1974a). Comparison with artificially derived hybrids seem to confirm this assumption.In P. juarezensis there seem to be no fixed characters, only attributes (sensu Davis & Nixon, 1992), which may define individuals but not populations (and in this case not taxa either). Lanner’s explanation—that the few trees (in two widely separated localities) with predominantly 5-leaved fascicles represent the last individuals of a species “being introgressed out of existence”—is nothing but speculation.The ovuliferous cones of P. quadrifolia are morphologically very similar to those of P. monophylla, and usually quite indistinguishable. They have very pronounced apophyses, contrasting with those in P. cembroides and its subspecies. The seed integument is thin in both (=0.5 mm), whereas it is thick in P. cembroides. The fascicle sheaths of both Baja Californian species disintegrate quickly, without forming the more persistent small “rosettes” found in P. cembroides s.l. and some other pines more distantly related to it. Therefore, P. quadrifolia (including P. juarezensis) appears to be related to P. monophylla, and it is unlikely that P. juarezensis could merely be a variety of P. cembroides, while P. quadrifolia is to be maintained as a separate species, as Silba (1990) suggested.Distribution and Ecology: United States: California, in Riverside and San Diego Counties. Mexico: In Baja California Norte, extending from near the U.S. border in the Sierra Juárez S to the SW foothills of the Sierra San Pedro Martir at ca. 30°30'N. The altitudinal range of Pinus quadrifolia is 900-2400(-2700) m. It grows between the semidesert and the chaparral scrub zones (and partly within the latter) and the mixed coniferous forest on the highest parts of the mountains. It is more widely distributed and often more common than P. monophylla in the pinyon-juniper woodland, but occurs often with it. Pinus jeffreyi is the only other pine with which it occurs in Mexico. Juniperus californica and Quercus turbinella are common; in the chaparral zone many shrubs dominate, e.g., Adenostoma, Ceanothus, Artemisia, Cercocarpus, Rhus, Eriodictyon, Arctostaphylos, and Yucca. Most of these mountains are granitic, but in the south of the ranges more volcanic rock is found. Pinus quadrifolia often grows in cracks among boulders. Annual precipitation is a moderate 300-500 mm, but it is quite variable; most of it comes during winter cyclonic storms and there is a long dry season from spring through summer.
Phenology: Pollen dispersal is in March-April. -
Distribution
Mexico North America| Baja California Mexico North America|