  Range of Pinus johannis (2). Locations shown are approximate; see text for details on finding these pines in the wild. Adapted from a map by  www.expediamaps.com | Pinus johannis M.-F. Robert 1978Common NamesJohannis pine, dwarf piñon, piñon (2).Taxonomic notesSyn: P. culminicola var. johannis (R-P.) Silba 1985 (1).The validity of this taxon is disputed; Farjon and Styles (1) regard it as synonymous with P. cembroides var. bicolor (=P. discolor), but Perry (2), Price et al. (3), and M.P. Frankis (pers. comm., 20-Dec-1998) regard it as a valid species, and it here is so classified. An intermediate view is taken by Passini (4), who treats P. discolor as a synonym of P. johannis. P. discolor is clearly very close to this species but does differ slightly, and might best be treated as a variety of it. The combination Pinus johannis var. bicolor has however yet to be formally published. The view of Silba (5) that it is a variety of P. culminicola has some merit in showing that it is more closely related to P. culminicola than it is to P. cembroides, a fact subsequently demonstrated by Malusa (6) in a very detailed study, but there is no evidence for hybridisation between them where they are sympatric (M.P. Frankis, pers. obs.), and Silba's treatment is rejected here. DescriptionTree: Height 2-3(4) m, a multi-stemmed shrub or tree, rarely with a single, dominant trunk. Crown low, dense and rounded, spreading, with branches extending outward from the ground line as much as 3-4 m (2).Bark: In young trees smooth and gray; in older trees rough and scaly, but not deeply furrowed or ridged (2). Twigs: Dark gray, rough, the bases of the leaf bracts somewhat decurrent (2). Leaves: (2-)3(-4) per fascicle, 3-5 cm long, 0.9-1.2 mm thick; flexible, margins entire, stomata present only on the ventral surfaces, the dorsal surface dark green and the ventral surface glaucous white. Resin canals 2, external, dorsal; vascular bundle single. Fascicle sheaths are orange-brown, 3 mm long, fading gray, and curled backward into a rosette; later occasionally deciduous. Cotyledons (6-)9(-11) (2). Conelets: Brown, 9-11 × 5-7 mm, borne singly or in pairs on short slender peduncles (2, 7). Seed cones: Resinous, oblong, 3-4(-4.5) × 2-3 cm when closed, 4-5.5 cm wide when open, chestnut brown, opening at maturity and soon deciduous. The peduncle is 3-4 mm long, falling with the cone (2). Cone scales: Thin and stiff, the apophyses irregularly rhomboid, small, thin, flat or slightly raised, 10-15 mm wide, with a weak transverse ridge; umbo dorsal, depressed, the prickle minute and soon deciduous. Only the central (3-)8-15 scales are seed-bearing, those at the base and apex of the cone generally very small and sterile (2, 7). Seeds: Dark orange-brown with a rudimentary 0.5-1 mm wing that remains in the cone after seed release; about 11-14 mm long and 10 mm wide, the seed coat or shell 0.5-1.0 mm thick, hard; about 2,200 seeds/kg; endosperm white; edible (2, 7). Wood: Pale yellowish brown, used only for fuel (2). RangeMexico: Scattered in the higher ranges of W Coahuila, Nuevo León and Zacatecas at 1700-2800 m altitude (1, 2, 7). The type locality is"only in a very limited area near the towns of Concepción del Oro and Mazapil, state of Zacatecas. More recently a number of small populations have been reported in western Coahuila and in the area between the towns of Miquihuana and Aramberri, Nuevo León... In Nuevo León they were growing with P. nelsoni at about 2,800 m" (2). Perry (2) describes the Concepción del Oro stand as occurring at 2,700 m on a steep slope of practically bare limestone, in the company of P. cembroides. The area has 300-400 mm annual precipitation and average annual temperature of 16°C. Frosts are common during December and January.Big TreeThe tallest I saw (7) in NE Mexico was about 4 m tall, on a single erect stem about 15-20 cm dbh, beside a dirt road on the west slope of Cerro Peña Nevada, 23°49'N 99°53'W, at 2680 m altitude (M.P.Frankis 179, 15 Nov 1991 [cited in error in (1) as at 3500 m]). Most were 2-3.5 m tall, not erect, and branched close to the base, similar to P. culminicola.OldestProbably not long-lived; no thick stems nor any other indication of great age seen (7).DendrochronologyEthnobotany"The branches of this small piñon are occasionally used for firewood and the seeds are collected for food" (2).With its very attractive blue-green foliage, it is potentially a valuable slow-growing ornamental species for small gardens in arid areas, but it is scarcely in cultivation yet. USDA hardiness zone 8. ObservationsThe type locale"is not difficult to find by following Mexico Highway 54 south from Saltillo for about 112 km. Look for a turn off on the right to Concepción del Oro. The road is paved to Concepción del Oro (about 3 km), but from there to Mazapil it is narrow, steep and unpaved. Though the pines can be found only a few kilometers from Concepción del Oro, it would be best to plan collections during the dry winter months, November-February" (2).It can also be seen scattered in the high valleys between San Antonio de las Alanzas and Monterrey around the Nuevo León / Coahuila border; these populations have only been discovered in recent years and are not mapped by Perry (2), but are shown by Farjon & Styles (1). At some of these sites it is separated from populations of P. culminicola by under 5 km and 400 m of altitude; despite this close proximity, no hybrids have been observed between these closely related taxa. Throughout its range, it also often occurs intimately mixed with P. cembroides, but again, no evidence of hybridisation has been found. RemarksP. johannis was named after Mlle. Robert's fiancé, Johann Passini, whom she later married; she published subsequent papers first as M.-F. Robert-Passini and then as M.-F. Passini.Citations(1) Farjon & Styles 1997.(2) Perry 1991. (3) Price et al. 1998. (4) Passini 1994. (5) Silba 1985. (6) Malusa 1992. (7) M.P. Frankis field notes, NE Mexico Nov 1991. Much of this page was prepared by M.P. Frankis, Feb-1999. |
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