Living organisms are subdivided into 5 major kingdoms, including the Monera, the Protista (Protoctista), the Fungi, the Plantae, and the Animalia. Each kingdom is further subdivided into separate phyla or divisions. Generally "animals" are subdivided into phyla, while "plants" are subdivided into divisions. These subdivisions are analogous to subdirectories or folders on your hard drive. The basic characteristics of each kingdom and approximate number of species are summarized in the following table:
Prokaryotic Cells Without Nuclei And Membrane-Bound Organelles
1. Kingdom Monera [10,000 species]: Unicellular and colonial--including the true bacteria (eubacteria) and cyanobacteria (blue-green algae).
Eukaryotic Cells With Nuclei And Membrane-Bound Organelles:
2. Kingdom Protista (Protoctista) [250,000 species]: Unicellular protozoans and unicellular & multicellular (macroscopic) algae with 9 + 2 cilia and flagella (called undulipodia).
3. Kingdom Fungi [100,000 species]: Haploid and dikaryotic (binucleate) cells, multicellular, generally heterotrophic, without cilia and eukaryotic (9 + 2) flagella (undulipodia).
4. Kingdom Plantae [250,000 species]: Haplo-diploid life cycles, mostly autotrophic, retaining embryo within female sex organ on parent plant.
5. Kingdom Animalia [1,000,000 species]: Multicellular animals, without cell walls and without photosynthetic pigments, forming diploid blastula.
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1. The five-kingdom system of classification for living organisms, including the prokaryotic Monera and the eukaryotic Protista, Fungi, Plantae and Animalia is complicated by the discovery of archaebacteria. The prokaryotic Monera include three major divisions: The regular bacteria or eubacteria; the cyanobacteria (also called blue-green algae); and the archaebacteria. Lipids of archaebacterial cell membranes differ considerably from those of both prokaryotic and eukaryotic cells, as do the composition of their cell walls and the sequence of their ribosomal RNA subunits. In addition, recent studies have shown that archaebacterial RNA polymerases resemble the eukaryotic enzymes, not the eubacterial RNA polymerase.
Archaebacteria also have introns in some genes, an advanced eukaryotic characteristic that was previously unknown among prokaryotes. In eukaryotic cells, the initial messenger RNA (M-RNA) transcribed from the DNA (gene) is modified (shortened) before it leaves the nucleus. Sections of the M-RNA strand called introns are removed, and the remaining portions called exons are spliced together to form a shortened (edited) strand of mature M-RNA that leaves the nucleus and travels to the ribosome for translation into protein. This process is known as "gene editing." Some authorities hypothesize that eukaryotic organisms may have evolved from ancient archaebacteria (archae = ancient) rather than from the common and cosmopolitan eubacteria. The archaebacteria could have flourished more than 3 billion years ago under conditions previously thought to be uninhabitable to all known life forms.
Although many conservative references place the archaebacteria in a separate division within the kingdom Monera, most authorities now recognize them as a 6th kingdom--The kingdom Archaebacteria. In fact, data from DNA and RNA comparisons indicate that archaebacteria are so different that they should not even be classified with bacteria. Systematists have devised a classification level higher than a kingdom, called a domain or "superkingdom," to accomodate the archaebacteria. These remarkable organisms are now placed in the domain Archaea. Other prokaryotes, including eubacteria and cyanobacteria, are placed in the domain Bacteria. All the kingdoms of eukaryotes, including Protista (Protoctista), Fungi, Plantae and Animalia, are placed in the domain Eukarya. The large molecular differences between the majority of prokaryotes in the kingdom Monera and the archaebacteria warrants a separation based on categories above the level of kingdom. In other words, the differences between the true bacteria and archaebacteria are more significant than the differences between kingdoms of eukaryotes.
Guillaume Lecointre and Hervé Le Guyader (2006) have published a remarkable book entitled The Tree of Life: A Phylogenetic Classification. The book includes the three major domains which are in turn subdivided into numerous branches (clades). An oversimplified 3-domain system of classification is shown in the following table. The number of subdivisions listed by G. Lecointre and H.L. Guyader for each domain are shown in parentheses.
Three Domains (Superkingdoms) Of Living Organisms
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I. Bacteria (19): Most of the Known Prokaryotes
Kingdom (s): Not Available at This Time
Division (Phylum) Proteobacteria: N-Fixing Bacteria
Division (Phylum) Cyanobacteria: Blue-Green Bacteria
Division (Phylum) Eubacteria: True Gram Posive Bacteria
Division (Phylum) Spirochetes: Spiral Bacteria
Division (Phylum) Chlamydiae: Intracellular Parasites
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II. Archaea (16): Prokaryotes of Extreme Environments
Kingdom Crenarchaeota: Thermophiles
Kingdom Euryarchaeota: Methanogens & Halophiles
Kingdom Korarchaeota: Some Hot Springs Microbes
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III. Eukarya (35): Eukaryotic Cells
Kingdom Protista (Protoctista)
Kingdom Fungi
Kingdom Plantae
Kingdom Animalia
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2. The kingdom Protista includes a diverse array of organisms, from minute flagellated cells to macroscopic kelp. The smallest microscopic organisms are termed protists, consequently some biologists prefer to call this kingdom the Protoctista rather than Protista. All members of this vast phylum have nucleated cells and live in aquatic habitats (freshwater and marine). According to Lynn Margulis, K.V. Schwartz and M. Dolan (1994), the cells of all Protoctista originally formed by bacterial symbioses (symbiogenesis).
Members of the kingdom Protoctista are not animals, which develop from an embryo called a blastula; they are not plants, which develop from an embryo that is not a blastula but is retained in the mother's tissue; they are not fungi which develop from spores and lack cilia and flagella (called undulipodia) at all stages of development; they are not monerans, which have prokaryotic cells.
Fossil protoctists, with thick-walled resting stages or cysts, can be extracted from shale treated with hydroflouric acid. One of the richest sources of bizarre fossil protoctists was discovered in southern Australia during the late 1950s. Known as the Ediacaran biota, these deposits date back 600 million years ago. Some of these ancient protoctists may have been ancestral to certain animal and plant phyla. In fact, some flattened protoctists discovered in the Ediacaran biota had characteristics resembling lichens. [Lichens are organisms resulting from genetic mergers betweeen protists and fungi.] All the Ediacaran biota became extinct by about 530 million years ago and were replaced be shelled Cambrian animals.
Some general biology textbook authors place the microscopic, unicellular green algae (Division Chlorophyta) in the Kingdom Protista, and place the larger, multicellular (macroscopic) green algae (Division Chlorophyta) in the Kingdom Plantae. They also place the macroscopic, multicellular brown algae (Division Phaeophyta) and red algae (Division Rhodophyta) in the Kingdom Plantae. In fact, some authors place all of the algae divisions in the Kingdom Plantae. Although the Kingdom Protista includes mostly unicellular organisms, the WAYNE'S WORD staff feels that these algal divisions belong in the Kingdom Protista (Protoctista) rather than the Kingdom Plantae.
3. Some members of the Kingdom Fungi (in the fungal classes Ascomycetes and Basidiomycetes) are associated with algal cells of the Kingdom Protista (in the algal division Chlorophtya) and/or prokaryotic cyanobacteria of the Kingdom Monera. This complex symbiotic, mutualistic relationship is called lichen. Lichens are essentially lichenized fungi containing unicellular monerans and/or protists.
4. There are approximately 1.6 million species of living organisms on earth. This number may be much higher because new species are continually being discovered each day, particularly insects and nematodes in remote tropical regions. However, at the present rate of destruction, most of the virgin tropical rain forest will be annihilated by the end of the 20th century, so many species will never be known to humans. It is estimated that 99 percent of all the species that have ever lived on earth were already extinct before humans ever walked on this planet. Although humans have a phenomenal impact on the ecology of earth, they are relative newcomers on this great planet. It is estimated that the earth is over 4.5 billion years old, and ancient life forms (such as the cyanobacteria) appeared about 2-3 billion years ago. If the geologic history of the earth is compared to a 24-hour time scale, the first multicellular organisms do not appear until just after 8:00 P.M. and humans are not on the scene until less than a minute before midnight.
5. There are more than one million species of animals (Kingdom Animalia), more than all the other kingdoms combined. More than half of all animal species are insects (800,000 species), and beetles (300,000 species) comprise the largest order of insects (one fifth of all species--using a total of 1.5 million). In fact, if all the species of plants and animals on earth were lined up at random, every 5th species would be a beetle.
6. Viruses: Viruses do not belong to the above 5 kingdoms of life. They are much smaller and much less complex than cells. They are macromolecular units composed of DNA or RNA surrounded by an outer protein shell. They have no membrane-bound organelles, no ribosomes (organelle site of protein synthesis), no cytoplasm (living contents of a cell), and no source of energy production of their own. They do not exhibit autopoiesis--i.e. they do not have the self-maintenance metabolic reactions of living systems. Viruses lack cellular respiration, ATP-production, gas exchange, etc. However, they do reproduce, but at the expense of the host cell. Like obligate parasites, they are only capable of reproduction within living cells. In a sense, viruses hijack the host cell and force it to produce more viruses through DNA replication and protein synthesis. Outside of their host cells, viruses can survive as minute macromolecular particles. Viruses may attack animals and plants. Infectious human viruses can be dispersed though the air (airborne viruses) or body fluids (HIV virus). Epidemic viruses (such as HIV) that are passed from person to person via sexual conjugation are remarkably similar to computer viruses. Unfortunately in humans there is no resident antivirus program to alert you of a potential infection, or to quickly scan your body and delete the invader once it has entered your system. Humans must rely on their amazing antibody and cell-mediated immune response, one of the most complex and remarkable achievements in the evolution of living systems.
The discovery of a virus called "mimivirus" in 1992 complicates the placement of viruses in the overall classification scheme for living organisms. Whether mimivirus should be placed in an existing domain (superkingdom), or in its own domain, remains to be seen. Prior to this discovery, viruses were generally considered nonliving until they hijack a living cell. Officially, this virus got its name because it mimics bacteria in size and complexity. Mimivirus was found inside an amoeba within a cooling tower in Bradford, UK. [The cooling tower was being investigated as the source of an influenza outbreak.] Mimivirus is the largest known virus, about 0.8 micrometers (800 nanometers) across. In fact it is larger than the bacterium causing gonorrhea. The virus genome contains 1.2 million bases, more than many bacteria. The bases make up 1,260 genes, which makes it as complex as some bacteria. Most viruses use either DNA or RNA to carry their genetic information, but mimivirus has both of these nucleic acids. In addition, mimivirus can make about 150 of its own proteins, and can even repair its own DNA if it gets damaged. Normal viruses are not capable of protein synthesis or DNA repair on their own, they must rely on the organelles of their host cells for these activities.
For more information, see D. Raoult, et al. "The 1.2-Mb Genome Sequence of Mimivirus." Science Published On-line, DOI: 10.1126/Science.1101485 (2004); B. La Scola et al. "A Giant Virus in Amoebae." Science 299 (5615): 2033 (2003).
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The most morphologically and biochemically diverse, non-animal kingdom is the Plantae or Plant Kingdom. It is subdivided into the following 10 phyla or divisions. Note: These names vary considerably, depending on which botany reference you are using.
Categories Within The Kingdom Plantae
- Nonvascular Plants: No water-conducting cells (xylem).
- Vascular plants: Xylem tissue, true roots, stems & leaves.
[The following divisions are often placed in Division Tracheophyta]
Pteridophytes: Spores but no seeds
Spermatophytes: Seed Plants
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Each of the plant divisions in the above table are further subdivided into successively smaller and smaller subcategories. The complete hierarchal breakdown is Kingdom-Phylum (Division)-Class-Order-Family-Genus-Species. To remember this sequence, the following mnemonic device is often helpful:
King--Phillip--Came--Over--For--Good--Soup
A Biological and Military (Army) Organizational Hierarchy Compared:
Biological Organization
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Military Organization
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Kingdom (one or more phyla)
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Brigade (two or more regiments)
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Phylum (one or more classes)
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Regiment (two or more battalions)
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Class (one or more orders)
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Battalion (two or more companies)
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Order (one or more families)
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Company (two or more platoons)
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Family (one or more genera)
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Platoon (two or more squads)
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Genus (one or more species)
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Squad (a group of 12 soldiers)
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Species (a distinct kind or unit)
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Soldier (a distinct kind or unit)
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The following table compares the complete taxonomic hierarchy of a marine lichen of the rocky Pacific coast Verrucaria maura with the minute aquatic flowering plant Wolffia borealis:
Kingdom |
Fungi |
Plantae |
Phylum |
Eumycota |
Tracheophyta |
Class |
Ascomycetes |
Angiospermae |
Order |
Pyrenulales |
Arales |
Family |
Verrucariaceae |
Lemnaceae |
Genus |
Verrucaria |
Wolffia |
Species |
maura |
borealis |
The plant kingdom includes nonvascular and vascular plants. Nonvascular plants lack a water-conducting system of tubular cells (called xylem tissue), and do not have true roots, stems and leaves. Like algae and fungi, the plant body of some nonvascular plants is often called a thallus. Nonvascular plants are all placed in the Division Bryophyta, including the mosses and liverworts. The vast majority of the plant kingdom are vascular, with tubular, water-conducting cells called xylem tissue. Like a microscopic pipeline system, they are arranged end-to-end from the roots to the leaves. Unlike nonvascular plants, they have true roots, stems and leaves. Some references place all the vascular plants in a separate phylum or division called the Tracheophyta. Most botanists now subdivide vascular plants into 9 divisions. More primitive vascular plants that reproduce by spores, but without seeds, are called pteridophytes, and include the 4 divisions Psilophyta (whisk ferns), Lycophyta (club mosses), Sphenophyta (horsetails), and Pterophyta (ferns). Seed-bearing vascular plants are called spermatophytes and include the primitive gymnosperms (with immature seeds or ovules naked and exposed directly to pollen) and the more advanced angiosperms (with ovules enclosed in an ovary that ripens into a fruit). Gymnosperms include the 4 divisions Cycadophyta (cycads), Ginkgophyta (maidenhair tree), Gnetophyta (mormon tea & the bizarre South African Welwitschia), and the Coniferophyta (conifers). The angiosperms are placed in the single division Anthophyta which includes all the flowering plants and 90 percent of all the plant kingdom.
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Twenty of the more than 100 species of Pinus on earth. All of these pines are native to the state of California, USA. 1. Monterey Pine (P. radiata), 2. Bishop Pine (P. muricata), 3. Santa Cruz Island Pine (P. remorata), 4. Whitebark Pine (P. albicaulis), 5. Limber Pine (P. flexilis), 6. Beach Pine (P. contorta), 7. Lodgepole Pine (P. murrayana), 8. Western White Pine (P. monticola), 9. Knobcone Pine (P. attenuata), 10. Bristlecone Pine (P. longaeva), 11. Foxtail Pine (P. balfouriana), 12. Four-Leaf Pinyon (P. quadrifolia), 13. Two-Leaf Pinyon (P. edulis), 14. One-Leaf Pinyon (P. monophylla), 15. Ponderosa Pine (P. ponderosa), 16. Coulter Pine (P. coulteri), 17. Digger Pine (P. sabiniana), 18. Torrey Pine (P. torreyana), 19. Jeffrey Pine (P. jeffreyi), 20. Sugar Pine (P. lambertiana).
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Note: In the Jepson Flora of California (1993), Pinus remorata is now considered a synonym of P. muricata. Another species (left image) called the Washoe Pine (P. washoensis), with cones similar to a miniature Jeffrey Pine, is now recognized for California. In addition, the Beach and Lodgepole Pines are now recognized as subspecies of P. contorta, rather than separate species.
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According to R.M. Lanner (Conifers of California, 1999), there may be other significant changes in the pines of California. Allozyme studies in two-leaf pinyons (Pinus edulis) of the New York Mountains indicate that these populations are biochemically (and genetically) consistent with nearby one-leaf pinyon (Pinus monophylla), and that P. edulis may not occur in California. The unusual New York Mountains population appears to be a 2-needle variant of P. monophylla. The four-leaf or Parry pinyon of San Diego County (P. quadrifolia) may be a hybrid between P. monophylla and Sierra Juárez pinyon (P. juarezensis) of northern Baja California. According to Lanner, the latter species has five needles per fascicle and occurs in San Diego County. The hybrid hypothesis might explain the perplexing variation in needle number for P. quadrifolia, with clusters of three, four and five.
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Foxtail pines (Pinus balfouriana) on the 11,000 ft (3353 m) slopes of Alta Peak. The 13,000 ft. (3962 m) crest of the Great Western Divide of the Sierra Nevada can be seen in the distance.
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Selection & Genetic Drift In California Cypress
Millions of years ago, cypress woodlands containing one or more ancestral species of the cone-bearing genus Cupressus once dominated vast areas of California. During the past 20 million years, as mountains were uplifted and the climate became increasingly more arid, most of these extensive cypress woodlands vanished from the landscape. In some areas, the cypress were probably unable to compete with more drought resistant, aggressive species, such as impenetrable chaparral shrubs and desert scrub. Although cypress are fire-adapted with serotinous seed cones that open after a fire, they are vulnerable if the fire interval occurs too frequently, before the trees are old enough to produce a sufficient cone crop. Chaparral shrubs quickly resprout after a fast-moving brush fire from well-established subterranean lignotubers. This may explain why some cypress groves occur in very rocky, sterile sites with poor soils where the chaparral shrubs can't compete as well.
Today this fascinating genus is represented by 10 species (or 8 species and 2 subspecies), confined to isolated groves scattered throughout the coastal and inland mountains, from the Mexican border to Oregon. Because some of these populations became isolated into "arboreal islands," gradual genetic changes over millions of years resulted in the present-day species and subspecies. This is somewhat analogous to the evolution of Darwin's finches on the Galapagos Islands. It is quite likely that natural selection played a role in cypress speciation. Cypress of arid inland mountains and valleys (such as Piute cypress, Macnab cypress, Cuyamaca cypress, and Arizona cypress) have glandular (resinous) foliage and are more drought resistant. Coastal species (such as Monterey cypress, Gowen cypress, Santa Cruz cypress and Mendocino cypress) are generally nonglandular without resin glands on the leaf surfaces. Some phenotypic variability, particularly between different isolated groves of the same species may be due (in part) to genetic drift. These differences include slight variations in foliage, bark characteristics (exfoliating vs. persistent), and the general shape of seed cones. These differences attributed to genetic drift are analogous to racial differences in people, such as different blood type percentages and facial characteristics.
The relatively short period of isolation for Cupressus (cypress) species may be one of the reasons taxonomists disagree on the total number of species native to North America. In 1948, Carl B. Wolf published his "Taxonomic and Distributional Studies of the New World Cypresses" (El Aliso 1: 1-250). Dr. Wolf listed a total of 15 species, one in Baja California, one on Guadalupe Island off the coast of Baja California, one in Mexico and Central America, two in Arizona, and 10 in California. In 1953, the number of U.S. species was reduced to six by Dr. Elbert Little, Jr. in his Check List of Native and Naturalized Trees of the United States (USDA Agriculture Handbook No. 41). These numbers have fluctuated greatly in subsequent publications. In addition, the nursery trade has added several cultivated varieties, including at least four different cultivars for the Arizona cypress.
New evidence from DNA sequencing has further complicated the number of cypress species, including the transfer of other conifer genera into the genus Cupressus. For example, the Jepson Manual of California Plants lists ten species; however, two of these C. nootkatensis (Alaska cedar) and C. lawsoniana (Port Orford cedar) were formerly placed in the genus Chamaecyparis. It is possible that some of the isolated species of Cupressus in California and Arizona have not been isolated long enough to warrant the status of a species. In fact, this is why most modern floras have consolidated four species into subspecies of the Arizona cypress (C. arizonica). These species have been isolated long enough for genetic drift to occur, but perhaps not long enough for the development of distinct species populations.
Left: Seed cones of cypress (Cupressus) from groves in southern California. A. Tecate cypress (C. forbesii), B. Sargent cypress (C. sargentii), C. Piute cypress (C. nevadensis) [Syn. C. arizonica ssp. nevadensis], D. Cuyamaca cypress (C. stephensonii) [Syn. C. arizonica spp. stephensonii], E. Smooth-bark Arizona cypress (C. glabra) [Syn. C. arizonica ssp. glabra], F. Rough-bark Arizona cypress (C. arizonica) [Syn. C. arizonica ssp. arizonica]. Right: Seed cones of cypress from groves in central and northern California. G. Monterey cypress (C. macrocarpa), H. Gowen cypress (C. goveniana) [Syn. C. goveniana ssp. goveniana], I. Santa Cruz cypress (C. abramsiana), J. Sargent cypress (C. sargentii), K. Mendocino cypress (C. pygmaea) [Syn. C. goveniana ssp. pigmaea], L. Macnab cypress (C. macnabiana), M. Modoc cypress (C. bakeri).
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Male (pollen) cones of the Piute cypress (Cupressus nevadensis) [syn. C. arizonica ssp. nevadensis). Each scalelike leaf bears a dorsal gland that exudes a resin droplet (red arrow). Interior cypress species such as this one typically have glaucous, resinous foliage, presumably an adaptation to dry, arid habitats.
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A. Foliage and pollen cones of the Smooth-bark Arizona cypress (Cupressus glabra) [Syn. C. arizonica ssp. glabra]. B. Foliage of the Tecate cypress (C. forbesii). The scalelike leaves of Arizona cypress are glaucous and very glandular (sticky). The scalelike leaves of Tecate cypress are green and without dorsal resin glands.
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Left: Monterey cypress (Cupressus macrocarpa) in Point Lobos State Park on the coast of central California. Right: Grove of Piute cypress (C. nevadensis) in the Piute Mountains, with Lake Isabella and the snow-covered Sierra Nevada in the distance. The Piute cypress are more drought resistant, with gray (glaucous), glandular (resinous) foliage similar to the Arizona cypress. In fact, some botanists now consider the Piute cypress to be a subspecies of the Arizona cypress and have named it C. arizonica ssp. nevadensis.
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A grove of Sargent cypress (Cupressus sargentii) in the San Rafael Mountains of Santa Barbara County, California. This species typically grows on outcrops of serpentine in the Coast Ranges of central and northern California. Serpentine is a shiny rock with a waxy luster and feel. It varies in color from creamy white and shades of green to black. In California, many species of rare and endangered plants are endemic to serpentine outcrops. Genetic drift has undoubtedly occured in isolated cypress groves such as this one, which are often referred to as "arboreal islands."
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Other Members Of The Division Coniferophyta
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Podocarpus gracilior, a member of the Podocarpaceae native to eastern Africa. Although it is sometimes called "fern pine" it does not belong to the genus (Pinus); however, like pines and other cone-bearing species, it does belong to the Division Coniferophyta. Minute female cones are composed of 2-4 reduced scales, but usually only one scale bears an ovule that matures into a seed. There is little resemblance to a cone in the mature seed. The seed has a hard coat surrounded by a fleshy outer layer (aril). The drupelike seed often sits on a fleshy red or purple base or cone axis that is called an aril in some references. The seeds are similar to the California nutmeg (Torreya californica) and Pacific yew (Taxus brevifolia), members of the closely-related Yew Family (Taxaceae). In the latter species, the naked seed sits partially exposed in a red, cup-shaped aril. Podocarpus seeds are often referred to as fleshy fruits called drupes, but this is incorrect because drupes develop from the ovaries of flowering plants. Another group of conifers with fleshy seed-bearing structures are the junipers (Juniperus) in the Cypress Family (Cupressaceae). Junipers actually produce small cones with fleshy, fused scales bearing one-several seeds. Podocarpus is a dioecious species, with separate male and female trees in the population. Podocarpus has an ancient lineage dating back to distant relatives that lived during the Jurassic Period 170 million years ago.
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California nutmeg (Torreya californica), a member of the Division Coniferophyta, Order Taxales, Family Taxaceae. Like Podocarpus, the "naked" seed is enclosed in a fleshy, outer layer (called an aril) which superficially resembles a one-seeded fruit of an angiosperm. The name "nutmeg" is derived from its superficial resemblance to the fruit of the true nutmeg (Myristica fragrans).
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Pacific yew (Taxus brevifolia), another member of the Division Coniferophyta, Order Taxales, Family Taxaceae that occurs in northern California, Oregon and Washington. Unlike the California nutmeg, the naked seed is not completely enclosed by the fleshy aril. Instead, the seed sits in a cup-shaped aril. Since this species is native to regions of the Pacific northwestern United States containing the timber tree Douglas fir (Pseudotsuga menziesii), it was once considered a weedy species when areas of the forest were logged. Luckily, the Pacific yew still survives because it is now considered to be an exceedingly valuable species. An extract from the bark (and needles) called taxol has been found to be a very effective treatment for ovarian and breast cancers. It is very important to preserve natural, old growth forests with a diversity of species, some of which may prove to be valuable medicines for the treatment of diseases.
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Santa Lucia Fir (Abies bracteata)
The Santa Lucia or bristlecone fir (Abies bracteata) has a tall, slender, steeple-like crown. Seed cones are produced near the top of the slender spire, and they are some of the most unusual cones of all cone-bearing trees on earth. Long, spine-like bracts extend outwardly from between the cone scales, and resemble the antennae of a space satellite. This uncommon and remarkable fir tree is endemic to steep, rocky slopes in the Santa Lucia Range of California's Coast Ranges.
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Santa Lucia fir (Abies bracteata), a remarkable California endemic.
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Using fossil evidence and computerized cladistic analyses, it is generally concluded that evolution in the plant kingdom proceeded from nonvascular, spore-bearing ancestors to vascular, seed-bearing, flowering plants, as more and more advanced morphological and biochemical traits gradually appeared along the geologic time scale. This is somewhat analogous to the evolution of Microsoft; however, unlike Microsoft, the phenomenal success of flowering plants is based on natural selection rather than timely, strategic decisions by brilliant top level executives such as Bill Gates.
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