Monographs Details: Pinus muricata var. muricata
Authority: Farjon, Aljos K. & Styles, Brian T. 1997. Pinus (Pinaceae). Fl. Neotrop. Monogr. 75: 1-291. (Published by NYBG Press)
Family:Pinaceae
Synonyms:Pinus edgariana Hartw., Pinus muricata var. anthonyi Lemmon, Pinus remorata H.Mason, Pinus muricata subsp. remorata (H.Mason) A.E.Murray, Pinus muricata var. stantonii Axelrod
Description:Variety Description - Shrub or small tree (in Mexico), height to 4-10 (-15?) m, dbh to 20-50 cm. Trunk monopodial, often branching near the ground, erect or curved and crooked. Bark rough and scaly, exfoliating, on larger trunks with deep longitudinal fissures, dark brown to grey, on young trees and branches thin, exfoliating in papery flakes exposing pale brown inner bark. Branches long, relatively thick, spreading or ascending, in shrubs often assurging, persistent, forming an open, broad, irregular crown. Shoots multinodal, rough with large, short decurrent, persistent pulvini. Cataphylls ca. 10 mm long, subulate, curved or reflexed, scarious, with erose-ciliate margins, brown, early deciduous. Vegetative buds ovoid-acute, the terminal buds 10-15 mm long, the laterals smaller, not or slightly resinous; the scales imbricate, with free apices, subulate, with erose-ciliate margins, light brown. Fascicle sheaths 10-14 mm long initially, reduced to <10 mm on mature fascicles, ripped at parting of leaves but persistent, hyaline-whitish, brown at base. Leaves in fascicles of 2, in rigid tufts at the ends of branches, persisting 2-3 years, spreading ca. 45° from the shoot, straight or slightly curved, rigid, (7-)10-14(-16) cm X 1.3-2 mm, with serrulate margins, acute, light green or dark green. Stomata on both faces of leaves, with 6-9 lines on the abaxial, convex face and 4-7 lines on the adaxial face. Leaf anatomy: Cross section semi-circular; epidermis very thick; hypodermis uniform, with 2-3 layers of cells; resin ducts 2-10(-14), medial, narrow; stele oval in cross section; cell walls of endodermis uniform, thin; vascular bundles 2, distinctly separated. Pollen cones crowded near the proximal end of a new shoot (not always distinct due to the multinodal habit), oblong-cylindrical, 15-20 mm long, pink to reddish, turning yellowish brown. Seed cones subterminal, at the base of the subsequent shoot, solitary or in whorls of 2-5 on stout, 5-10 mm long, bracteate peduncles, reflexed, tenacious, mature cones seemingly sessile, opening only partly. Immature cones ovoid, with prominent spines, initially purplish red, maturing in two seasons. Mature cones serotinous, narrowly ovoid to ovoid-attenuate when closed, or strongly asymmetrical, broadly ovoid with long, spiny apophyses, 5-7(-8) X 4-5 (-6) cm when (half) open. Seed scales ca. 70-100, parting very slowly except those at the base or lower half of the cone, oblong, straight or slightly curved, thick woody, purplish brown, with grey-brown marks of seed wings on the adaxial side. Apophysis very variable, from slightly raised to extremely elongated (bifacial-conical), especially on the upper side of the cone, rhombic to pentagonal in outline, sometimes curved, transversely keeled, up to 15 mm wide and 20 mm long, from dull, dark brown to lustrous light brown. Umbo dorsal, obtuse to acute, if enlarged forming a flattened, curved spine, armed with a sharp prickle in obtuse forms, 2-10 mm long. Seeds obliquely ovoid, slightly flattened, 5-6 X 3-4.5 mm, grey to black. Seed wings articulate, effective, held to the seed by two thin, oblique claws, obovate-oblong to dolabriform, 14-18 X 5-8 mm, yellowish brown to grey-brown. Cotyledons 4-6.

Discussion:Uses. Due to its bushy habit and very restricted occurrence in Mexico, Pinus muricata is not commercially used. There has been some local “logging” in the past, but due to the low population density in the region, this use is not extensive. There is evidently cattle grazing in the area, but we do not know its effects, if any, on these relict stands of pines.

In a brief series of descriptions of five “new” pines collected by T. Coulter in California, Don (1836) described Pinus muricata, apparently only with a cone at his disposal. It was collected at Coon Creek near San Luis Obispo at ca. 1000 m, according to Millar (1986b). It is a typically disjunct, relict taxon which had a wider distribution in the geologic past and is now being reduced primarily through loss of habitat due to coastal abrasion (Mason, 1932; Axelrod, 1983).

The populations are often very heterogeneous, which is expressed in the variability of cone types, number of resin ducts in the leaves and stomatal anatomy. Analysis of mtDNA variation (Strauss et al., 1993) and cpDNA variation (Hong et al., 1993) has revealed a similar heterogeneity, at least among the Californian populations, confirming the morphologically based findings. While intrapopulation variation of mtDNA and cpDNA appears to be limited, polymorphy, especially in cone types, occurs also within populations. On Cerro Colorado, cones of both extremes-nearly symmetrical, with flat apophyses and small, prickly umbos (Farjon 260, Hughes & Styles 178) and asymmetrical, with very strongly developed apophyses and umbos (Broder 205)-have been collected. Most stands are situated in chaparral, a vegetation type adapted to frequent brush fires. Reseeding from one or a few individuals with ripe seed, with much of the gene pool lost, may have caused a “founder effect” eliminating intermediates (see also Millar, 1986b).

This heterogeneity seems to have led to the description of numerous taxa. Only a northern variety, occurring outside our region, is currently accepted by most botanists (Farjon, 1993). Cone types, as emphasized by Axelrod (1983) in order to be able to classify Pleistocene fossil cones, are of little value in determining genetic relationships in this species.

Distribution and Ecology: United States: In California on and near the coast of the mainland counties of Monterey (Monterey Peninsula), San Luis Obispo, and Santa Barbara; also on Santa Cruz and Santa Rosa Islands. The populations in N California were referred to as P. muricata var. borealis Axelrod. Mexico: Baja California Norte, in two localities on the mainland near the coast, W and SW of San Vicente. Reports of its occurrence on Cedros Island by various authors (Epling & Robinson, 1940; Martínez, 1948, even with a photograph) as well as on Guadalupe Island (e.g., Mason, 1932) are erroneous and the reports pertain to R radiata var. binata. In its locations in Mexico it is the only species of Pinus growing there; it is sometimes accompanied by Cupressus guadalupensis var. forbesii or Juniperus californica. The largest populations are on and near Cerro Colorado, an escarpment of eroded rhyolite on the N side of Río San Isidro, an intermittent stream. It is here where most collections have been made because it is next to the road, but to the NE there are small mountains with stands of this pine, mostly on the N-facing slopes. It occurs from near sea level to ca. 100 m. It grows within the chaparral zone influenced by (summer and autumn) fog and winter rain, probably amounting annually to ca. 500 mm. Often brush fires sweep the area, killing stands of pines, but the serotinous cones are adapted so as to open quickly after fire to release the seeds when the undergrowth has been cleared away. This often consists of Adenostoma, Arctostaphylos, Artemisia, Ceanothus, Heteromeles, Salvia, and other tall shrubs.

Distribution:Mexico North America| Baja California Mexico North America|