Index of Species Information

SPECIES:  Pseudotsuga macrocarpa


SPECIES: Pseudotsuga macrocarpa
AUTHORSHIP AND CITATION : Howard, Janet L. 1992. Pseudotsuga macrocarpa. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: [].
ABBREVIATION : PSEMAC SYNONYMS : NO-ENTRY SCS PLANT CODE : PSMA COMMON NAMES : bigcone Douglas-fir bigcone spruce bigcone Douglas-spruce hemlock false hemlock desert fir TAXONOMY : The currently accepted scientific name of bigcone Douglas-fir is Pseudotsuga macrocarpa (Vasey) Mayr [10,24]. There are no subspecies, varieties, or forms [3,10]. Bigcone Douglas-fir and Douglas-fir (Pseudotsuga menziesii) do not naturally hybridize because their ranges do not overlap. They readily hybridize, however, under laboratory conditions (see Management Considerations) [6]. LIFE FORM : Tree FEDERAL LEGAL STATUS : No special status OTHER STATUS : NO-ENTRY


SPECIES: Pseudotsuga macrocarpa
GENERAL DISTRIBUTION : Bigcone Douglas-fir occurs in mountains of southern California. It is distributed from the Santa Ynez Mountains in eastern Santa Barbara County and the Tehachapi Mountains of southwestern Kern County south to Julian, San Diego County [3,18]. It is cultivated in Hawaii [33]. ECOSYSTEMS : FRES21 Ponderosa pine FRES28 Western hardwoods FRES34 Chaparral - mountain shrub STATES : CA HI BLM PHYSIOGRAPHIC REGIONS : 3 Southern Pacific Border KUCHLER PLANT ASSOCIATIONS : K005 Mixed conifer forest K030 California oakwoods K033 Chaparral K034 Montane chaparral K035 Coastal sagebrush SAF COVER TYPES : 243 Sierra Nevada mixed conifer 245 Pacific ponderosa pine 246 California black oak 247 Jeffrey pine 248 Knobcone pine 249 Canyon live oak 255 California coast live oak SRM (RANGELAND) COVER TYPES : NO-ENTRY HABITAT TYPES AND PLANT COMMUNITIES : Low elevation (<3,500 feet [1,067 m]) bigcone Douglas-fir forest communities are disjunct, surrounded by extensive areas of chamise (Adenostoma fasciculatum) chaparral or coastal sage scrub [4,22,13]. In canyon bottoms, bigcone Douglas-fir communities intergrade with riparian forest [11]. From 3,500 to 4,500 feet (1,067-1,372 m), stands are more widespread. Canyon live oak (Quercus chrysolepis) is sympatric with bigcone Douglas-fir at these elevations. Together they form a two-layered forest consisting of a subcanopy of canyon live oak and an overstory of bigcone Douglas-fir [14,21]. Coulter pine (Pinus coulteri) replaces bigcone Douglas-fir on more xeric sites at these elevations [1]. From 4,500 to 5,500 feet (1,372-1,676 m), canyon live oak thins and bigcone Douglas-fir becomes increasingly abundant. At higher elevations, bigcone Douglas-fir decreases in importance and the bigcone Douglas-fir forest type is gradually replaced by mixed evergreen forest. Codominant species at higher elevations not listed as SAF Cover Types include incense-cedar (Calocedrus decurrens), California white fir (Abies concolor var. lowiana), singleleaf pinyon (Pinus monophylla), sugar pine (P. lambertiana), and interior live oak (Q. wislizeni) [18,32]. Publications listing bigcone Douglas-fir as a dominant or indicator species are as follows: Terrestrial natural communities of California [11]. Vegetation types of the San Bernardino Mountains [14]. Vegetation of the San Bernadino Mountains [21]. A vegetation classification system applied to southern California [26]. An introduction to the plant communities of the Santa Ana and San Jacinto Mountains [32].


SPECIES: Pseudotsuga macrocarpa
WOOD PRODUCTS VALUE : There is no current commercial market for bigcone Douglas-fir wood due to limited distribution and access [18]. It is heavy, hard, and fine grained but not durable. There is less sapwood than heartwood, and the latter contains pockets of resin. In the past, the wood was used locally for fuel and lumber [29]. IMPORTANCE TO LIVESTOCK AND WILDLIFE : Bigcone Douglas-fir stands provide habitat for black-tailed deer, black bear, and various small animals. These trees provide preferred spring habitat for black bear in the San Bernardino Mountains [18]. The seeds are eaten by various rodents and birds [10]. PALATABILITY : NO-ENTRY NUTRITIONAL VALUE : NO-ENTRY COVER VALUE : NO-ENTRY VALUE FOR REHABILITATION OF DISTURBED SITES : Bigcone Douglas-fir is used for watershed restoration. Radke and McDonald [18] reported that the Los Angeles County Department of Forestry has extensively planted the tree over a 50-year period for that purpose. Survival rates are not detailed. Bigcone Douglas-fir is recommended for reforestation of north-facing slopes within its range. Seed collecting and processing methods are detailed in the literature [25]. Trees planted on road cuts are often illegally harvested for use as Christmas trees [12]. OTHER USES AND VALUES : NO-ENTRY OTHER MANAGEMENT CONSIDERATIONS : Bigcone Douglas-fir populations are currently stable, with favorable rates of reproduction [3]. The tree is being considered for more extensive plantings in semiarid locales. Its favorable qualities include resistance to drought, fire, insects, decay, and damage from ozone [18,20]. The needles of older trees sometimes fade to yellow, drop, and trees appear dead only to sprout with renewed vigor within 2 years. The reason is unknown, although drought or insects may be possible causes [10]. Some bigcone Douglas-fir x Douglas-fir hybrids show promise for outplanting on drier sites in the Douglas-fir region [10,18]. These hybrids produce wood of comparable quality to that of Douglas-fir and have the drought tolerance of bigcone Douglas-fir [6].


SPECIES: Pseudotsuga macrocarpa
GENERAL BOTANICAL CHARACTERISTICS : Bigcone Douglas-fir is a native evergreen conifer from 50 to 100 feet (15-30 m) in height and 22 to 62 inches (56-155 cm) in DBH. Its growth form is straight and pyramidal. The deeply ridged bark is composed of thin, woodlike plates separating heavy layers of cork [3,10]; bark of trees over 40 inches (102 cm) in DBH is from 6 to 8 inches (36-64 cm) thick [31]. Main branches are long and pendulous, spreading from 20 to 50 feet (6-15 m) [1,3,15,18,21]. Side branches are few. The needles, from 0.8 to 1.2 inches (2-3 cm) long, are shed about every 5 years [10,24]. Female cones are from 4 to 7 inches (10-18 cm) long [28,24]. Seeds are large and heavy, each having a short rounded wing [18]. Roots are described as strong and spreading [18]. The largest known bigcone Douglas-fir is 91 inches (231 cm) DBH, 173 feet (53 m) tall, and is estimated to be from 600 to 700 years of age [10]. RAUNKIAER LIFE FORM : Phanerophyte REGENERATION PROCESSES : Sexual: The male strobili of an individual tree usually sheds pollen before female strobili open, preventing self-pollination [10]. Seed production begins at about 20 years of age; full seed production occurs at about age 40. Insect larvae destroy some immature seed. At times, they will destroy most of the crop. Heavy seed crops are rare. Seeds fall under the parent tree and only during high winds is wider seed dissemination possible [18]. Rodents and birds play a minor role in seed dispersal. Deer mouse, Merriam chipmunk, California ground squirrel, and western grey squirrel consume considerable portions of the seed crop [10]. Seed quality tends to be poor. In one laboratory test, seeds given cold-stratification treatment for 28 days proved 31 percent viable [18]. Seedbed requirements are broad. Seeds will germinate successfully on bare mineral soil or deep litter, although some seedling mortality from damping-off fungi occurs in deep litter. Germination is epigeal [18]. Bigcone Douglas-fir does not reproduce well where fires are frequent [3,18]. It reproduces best in locales undisturbed for at least 50 years, where emergents are shaded by canyon live oak. Survival is low on open sites unless soil remains moist, but seedlings surviving on these open sites attain top growth more rapidly than shaded seedlings [18,31]. With time, continuous shade becomes a liability. A span of 40 to 70 years commonly is required for bigcone Douglas-fir to penetrate through 16.5- to 27-foot (5-9 m) overstories of canyon live oak. Seedlings on higher elevation south or west slopes, however, enter the sapling-size class within 3 to 5 years [10]. Vegetative: Vegetative reproduction occurs after injury. Bigcone Douglas-fir does not sprout from the root crown, but intermediate-aged trees will sprout from the bole. In the Santa Ana Mountains, coppice sprouts developed in trees that were 5 to 45 inches (13-114 cm) in DBH and 25 to 300 years old [3]. Pole- and sawtimber-sized trees often regrow burned crowns (see Plant Response to Fire). Seedlings and saplings appear to have this ability as well [23]. Sprouting in young trees is not well documented, however. Some authorities claim that seedlings and saplings are not usually capable of sprouting following injury [14,18]. SITE CHARACTERISTICS : Climate: Bigcone Douglas-fir grows in a mediterranean climate, characterized by hot summers and wet, mild winters. Annual rainfall during a 30-year period on a bigcone Douglas-fir site in the San Gabriel Mountains averaged 30 inches (762 mm) and ranged from 10 to 49 inches (254-1,245 mm). Elevation: Bigcone Douglas-fir occurs between 2,000 and 8,000 feet (610 and 2,720 m) [10,24]. Soil and topography: Bigcone Douglas-fir grows in a wide variety of soil types [10]. At low elevation, it occurs near streams in moist, shaded canyons and draws where aspects are mostly north and east. At elevations from 4,440 to 5,600 feet (1,350-1,700 m), aspects include south- and east-facing slopes. At these elevations, bigcone Douglas-fir also grows on sloping hillsides, ridges, and benches. At higher elevations, it occurs on south and west aspects on all types of terrain. The average angle of slope on which bigcone Douglas-fire grows is 34.5 degrees. Slope angles range from 2 to 90 degrees, although these extremes are uncommon [3]. Plant associations: The number of plant associates in bigcone Douglas-fir communities is usually small [14]. Common overstory associates not listed under SAF Cover Types or Habitat Types and Plant Communities include bigleaf maple (Acer macrophyllum), California bay (Umbellularia californica), Digger pine (Pinus sabiniana), and white alder (Rhombus rhombifolia) [1,4,7,10,19]. Shrub associates include bigpod ceanothus (Ceanothus megacarpus), red shank (Adenostoma sparsifolium), Eastwood manzanita (Arctostaphylos glandulosa), toyon (Heteromeles arbutifolia), white sage (Salvia apiana), black sage (S. mellifera), purple sage (S. leucophylla), and California scrub oak (Quercus dumosa) [5,10]. Ground cover is usually sparse and may include California buckwheat (Eriogonum fasciculatum), wild onion (Allium spp.), scarlet beardtongue (Penstemon ternatus), chainfern (Woodwardia fimbriata), and western brackenfern (Pteridium aquilinium var. pubescens [10]. SUCCESSIONAL STATUS : Bigcone Douglas-fir seedlings are shade tolerant, while mature trees are intolerant [18]. The bigcone Douglas-fir forest is a climax type. In the absence of fire or other disturbance, bigcone Douglas-fir invades and dominates surrounding chaparral and oak communities [19]. Chaparral shrubs remain the dominant vegetation type of their zone because succession is constantly interrupted by drought accompanied by fire. Trees usually do not grow large enough during the fire-free period to become fire resistant [3,13]. Return of bigcone Douglas-fir to chaparral sites following disturbance probably requires centuries [14]. SEASONAL DEVELOPMENT : Bigcone Douglas-fir undergoes the following seasonal development: cone buds form: September to October [10] pollination: early March to mid-April [18] seed germination: March to May [10] cones mature: August to September [18] seed released: September to October {18} needles fall: September to October [10]


SPECIES: Pseudotsuga macrocarpa
FIRE ECOLOGY OR ADAPTATIONS : Bigcone Douglas-fir is one of only a few western conifers capable of sprouting following fire. Mature trees sprout vigorously from the branches and bole after burning. The trunk and main branches of bigcone Douglas-fir have many dormant adventitous buds, which are insulated from fire beneath thick bark. Fire or other damage to the tree stimulates cell division and growth in these buds. Consequently, epicormic stems grow from the axils of branches or from branch stubs along the trunk from the middle or upper one-third of the crown [10,18]. Bigcone Douglas-fir growing at low elevation often escapes fire damage because the mesic sites where it grows are not fire-prone [15]. Potential fuels at higher-elevation sites are sparse because understory vegetation is killed as trees mature and canopies close [31]. Litter layers of bigcone Douglas-fir forests are usually poorly developed due to the paucity of herbaceous understory and the sparse fall of needles from trees [14]. Survival of bigcone Douglas-fir is enhanced in rough terrain such as talus gullies and rugged canyons; such topography often impedes the momentum and intensity of spreading fires [23]. Rates of deforestation by slope class range from 84 percent for slopes of less than 10 degrees to 51 percent for slopes between 30 and 39 degrees. On slopes greater than 40 degrees, bigcone Douglas-fir survival is 75 percent [22]. FIRE REGIMES : Find fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find Fire Regimes". POSTFIRE REGENERATION STRATEGY : Secondary colonizer - off-site seed


SPECIES: Pseudotsuga macrocarpa
IMMEDIATE FIRE EFFECT ON PLANT : Fire kills bigcone Douglas-fir seeds. Most authorities claim that seedlings and saplings are killed by fire [10,14,18]. One study, however, showed that small burned trees sprouted following a fire of unreported severity in the Transverse Ranges [23]. The immediate effect of fire on young trees is therefore unclear, but mortality rates probably vary according to fire severity [22]. Pole- and sawtimber-sized trees are fire resistant. Aerial photographs of burns in the eastern Transverse Ranges show that 60 percent of bigcone Douglas-fir escaped defoliation during the period from 1938 to 1975 [23]. An additional 15 percent were scorched but not killed. Twenty-five percent of the trees were killed outright. The branchlets of defoliated trees are usually killed. Large main branches generally survive moderate-severity fire, but may be killed when severely burned. Trunks of severely burned trees are often protected from fatal damage by their thick bark [18]. Bigcone Douglas-firs growing sympatrically with canyon live oaks suffer less fire damage than other bigcone Douglas-firs. These oak seems to act as a buffer against the intense heat of chaparral fires burning into the bigcone Douglas-fir community [22,23]. DISCUSSION AND QUALIFICATION OF FIRE EFFECT : NO-ENTRY PLANT RESPONSE TO FIRE : Most sprouting occurs on trees scorched by surface fire. Trees subjected to crown fire rarely sprout [22]. Aerial photographs taken over the Meyer and Bear Burns of the Transverse Ranges at postfire years 1 and 2 showed that scorched stands with persistent dead foliage sprouted, but severely burned stands were killed. Field study of stands in the Village Burn (severity unreported) near Mount Baldy in the Transverse Ranges revealed sprouting in pole-sized trees and saplings as small as 10 feet (3 m) in height. All sprouts died on a number of such smaller individuals after postfire year 1, but other trees regained full crowns within 2 to 3 years [23]. The seed-producing ability of bigcone Douglas-fir is impaired for years [19]. Postfire natural regeneration generally takes decades. A survey of Transverse Range burns showed natural regeneration was almost nonexistent in recent burns. No offspring were found in burns less than 19 years old. Seedlings and saplings were most evident in burned areas free of further fire for 50 or more years. Bigcone Douglas-fir probably requires the development of an overstory before shade-tolerant seedlings will establish. Seed dispersal into these shaded areas is usually a reproductive barrier following stand-replacing fires where all potential parent trees are killed. Long-distance seed dispersal is inefficient in bigcone Douglas-fir [23]. DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : NO-ENTRY FIRE MANAGEMENT CONSIDERATIONS : Despite its ability to develop new crowns, bigcone Douglas-fir is not favored by frequent fire. Repeated fire depletes energy reserves and enlarges old wounds, and mortality is high in trees subjected to such fire regimes [18]. Bolton and Vogl [3] speculate that trees subjected to frequent fire loose their ability to sprout. In contrast to most conifers, however, fire-damaged trees are usually free from bark beetle attacks [10]. Bigcone Douglas-fir is adapted to a regime of long, fire-free intervals [7]. Frequent fire increases the number and density of the chaparral and woodland species in the spaces between bigcone Douglas-fir trees [14]. Occasional circumstances of stand defoliation, however, select in its favor because of its sprouting habit [23]. The interfaces of chaparral and bigcone Douglas-fir forests are in constant flux as environmental factors of fire, drought, precipitation, and erosion assert themselves [32]. The desiccating Santa Ana foehn winds that sweep the Santa Ana and San Jacinto mountains represent a fire danger to bigcone Douglas-fir trees. Santa Ana winds are capable of carrying fire downward from upslope mixed coniferous forests [28,32].


SPECIES: Pseudotsuga macrocarpa
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Riparian species distributions in relation to stream dynamics, San Gabriel River, California. Los Angeles: University of California. 120 p. Dissertation. [8971] 5. Capelli, Mark H.; Stanley, Stephen J. 1984. Preserving riparian vegetation along California's south central coast. In: Warner, Richard E.; Hendrix, Kathleen M., eds. California riparian systems: Ecology, conservation, and productive management. Berkeley, CA: University of California Press: 673-686. [5868] 6. Ching, Kim K. 1959. Hybridization between Douglas-fir and bigcone Douglas-fir. Forest Science. 5(3): 246-254. [18884] 7. Conard, Susan G. 1987. First year growth of canyon live oak sprouts following thinning and clearcutting. In: Plumb, Timothy R.; Pillsbury, Norman H., technical coordinators. Proceedings of the symposium on multiple-use management of California's hardwood resources; 1986 November 12-14; San Luis Obispo, CA. Gen. Tech. Rep. PSW-100. 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Trees and shrubs for erosion control of southern California mountains. Berkeley, CA: U.S. Department of Agriculture, Forest Service, California [Pacific Southwest] Forest and Range Experiment Station; California Department of Natural Resources, Division of Forestry. 72 p. [10689] 13. Horton, J. S. 1951. Vegetation. In: Some aspects of watershed management in southern California vegetation. Misc. Paper 1. Berkeley, CA: U.S. Department of Agriculture, Forest Service, California [Pacific Southwest] Forest and Range Experiment Station: 10-17. [10685] 14. Horton, Jerome S. 1960. Vegetation types of the San Bernardino Mountains. Tech. Rep. PSW-44. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 29 p. [10687] 15. Keeley, Jon E. 1981. Reproductive cycles and fire regimes. In: Mooney, H. A.; Bonnicksen, T. M.; Christensen, N. L.; [and others], technical coordinators. Fire regimes and ecosystem properties: Proceedings of the conference; 1978 December 11-15; Honolulu, HI. Gen. Tech. Rep. WO-26. Washington, DC: U.S. Department of Agriculture, Forest Service: 231-277. [4395] 16. Kuchler, A. W. 1964. Manual to accompany the map of potential vegetation of the conterminous United States. Special Publication No. 36. New York: American Geographical Society. 77 p. [1384] 17. Stickney, Peter F. 1989. Seral origin of species originating in northern Rocky Mountain forests. Unpublished draft on file at: U.S. Department of Agriculture, Forest Service, Intermountain Research Station, Fire Sciences Laboratory, Missoula, MT; RWU 4403 files. 7 p. [20090] 18. McDonald, Philip M. 1990. Pseudotsuga macrocarpa (Vasey) Mayr bigcone Douglas-fir. In: Burns, Russell M.; Honkala, Barbara H., technical coordinators. Silvics of North America. Volume 1. Conifers. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service: 520-526. [13412] 19. McDonald, Philip M.; Littrell, Edward E. 1976. The bigcone Douglas-fir - canyon live oak community in southern California. Madrono. 23(6): 310-320. [10662] 20. Miller, P. R.; Longbotham, G. J.; Longbotham, C. R. 1983. Sensitivity of selected western conifers to ozone. Plant Disease. 67: 1113-1115. [19641] 21. Minnich, Richard A. 1976. Vegetation of the San Bernardino Mountains. In: Latting, June, ed. Symposium proceedings: plant communities of southern California; 1974 May 4; Fullerton, CA. Special Publication No. 2. Berkeley, CA: California Native Plant Society: 99-124. [4232] 22. Minnich, Richard A. 1977. The geography of fire and big-cone Douglas-fir, Coulter pine and western conifer forests in the east transverse ranges, southern California. In: Mooney, Harold A.; Conrad, C. Eugene, technical coordinators. Proceedings of the symposium on the environmental consequences of fire and fuel management in Mediterranean ecosystems; 1977 August 1-5; Palo Alto, CA. Gen. Tech. Rep. WO-3. Washington, DC: U.S. Department of Agriculture, Forest Service: 443-450. [4875] 23. Minnich, Richard A. 1980. Wildfire and the geographic relationships between canyon live oak, Coulter pine, and bigcone Douglas-fir forests. In: Plumb, Timothy R., technical coordinator. Proceedings of the symposium on the ecology, management and utilization of California oaks; 1979 June 26-28; Claremont, CA. Gen. Tech. Rep. PNW-44. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station: 55-61. [7015] 24. Munz, Philip A. 1973. A California flora and supplement. Berkeley, CA: University of California Press. 1905 p. [6155] 25. Owston, Peyton W.; Stein, William I. 1974. Pseudotsuga Carr. Douglas-fir. In: Schopmeyer, C. S., ed. Seeds of woody plants in the United States. Agric. Handb. 450. Washington, DC: U.S. Department of Agriculture, Forest Service: 674-683. [7733] 26. Paysen, Timothy E.; Derby, Jeanine A.; Black, Hugh, Jr.; [and others]. 1980. A vegetation classification system applied to southern California. Gen. Tech. Rep. PSW-45. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 33 p. [1849] 27. Raunkiaer, C. 1934. The life forms of plants and statistical plant geography. Oxford: Clarendon Press. 632 p. [2843] 28. Trabaud, L. 1987. Fire and survival traits of plants. In: Trabaud, L., ed. Role of fire in ecological systems. Hague, The Netherlands: SPB Academic Publishers: 65-89. [16411] 29. Pinchot, Gifford. 1907. Bigcone spruce. Silvical Leaflet 10. Washington, DC: U.S. Department of Agriculture, Forest Service. 3 p. [19647] 30. U.S. Department of Agriculture, Soil Conservation Service. 1982. National list of scientific plant names. Vol. 1. List of plant names. SCS-TP-159. Washington, DC. 416 p. [11573] 31. Vogl, Richard J. 1967. Fire adaptations of some southern California plants. In: Proceedings, Tall Timbers fire ecology conference; 1967 November 9-10; Hoberg, California. No. 7. Tallahassee, FL: Tall Timbers Research Station: 79-109. [6268] 32. Vogl, Richard J. 1976. An introduction to the plant communities of the Santa Ana and San Jacinto Mountains. In: Latting, June, ed. Symposium proceedings: plant communities of southern California; 1974 May 4; Fullerton, CA. Special Publication No. 2. Berkeley, CA: California Native Plant Society: 77-98. [4230] 33. St. John, Harold. 1973. List and summary of the flowering plants in the Hawaiian islands. Hong Kong: Cathay Press Limited. 519 p. [25354]