Superstition

From Wikipedia, the free encyclopedia

Clay hamsa on a wall, etched with the Hebrew word for "good luck", believed to protect the inhabitants of the house from harm

 

Superstition is any belief or practice that is considered irrational or supernatural: for example, if it arises from ignorance, a misunderstanding of science or causality, a positive belief in fate or magic, or fear of that which is unknown. It is commonly applied to beliefs and practices surrounding luck, prophecy, and certain spiritual beings, particularly the belief that future events can be foretold by specific (apparently) unrelated prior events. The word superstition is often used to refer to a religion not practiced by the majority of a given society regardless of whether the prevailing religion contains alleged superstitions.

The superstitious practice of placing a rusty nail in a lemon is believed to ward off the evil eye and evil in general, as detailed in the folklore text Popular Beliefs and Superstitions from Utah.

 

Identifying something as superstition is generally pejorative. Items referred to as such in common parlance are commonly referred to as folk belief in folkloristics.

Etymology

Some cultures consider black cats to signify good or bad luck

 

The word superstition was first used in English in the 15th century, modelled after an earlier French superstition. The earliest known use as an English noun occurs in Friar Daw's Reply (ca. 1420), where the foure general synnes are enumerated as Cediciouns, supersticions, þe glotouns, & þe proude. The French word, together with its Romance cognates (Italian superstizione, Spanish superstición, Portuguese superstição, Catalan superstició) continues Latin superstitio.

While the formation of the Latin word is clear, from the verb super-stare, "to stand over, stand upon; survive", its original intended sense is less clear. It can be interpreted as "‘standing over a thing in amazement or awe", but other possibilities have been suggested, e.g. the sense of excess, i.e. over scrupulousness or over-ceremoniousness in the performing of religious rites, or else the survival of old, irrational religious habits.

The earliest known use as a Latin noun occurs in Plautus, Ennius and later by Pliny, with the meaning of art of divination. From its use in the Classical Latin of Livy and Ovid (1st century BC), the term is used in the pejorative sense it still holds today, of an excessive fear of the gods or unreasonable religious belief, as opposed to religio, the proper, reasonable awe of the gods. Cicero derived the term from superstitiosi, lit. those who are "left over", i.e. "survivors", "descendants", connecting it with excessive anxiety of parents in hoping that their children would survive them to perform their necessary funerary rites. While Cicero distinguishes between religio and superstitio, Lucretius uses only the term religio (only with pejorative meaning). Throughout all of his work, he distinguished only between ratio and religio.

The Latin verb superstare itself is comparatively young, being "perhaps not ante-Augustan", first found in Livy, and the meaning "to survive" is even younger, found in late or ecclesiastical Latin, for the first time in Ennodius. The use of the noun by Cicero and Horace thus predates the first attestation of the verb. It doesn't exclude that the verb might have been created and used after the name.

The term superstitio, or superstitio vana "vain superstition", was applied in the 1st century to those religious cults in the Roman Empire which were officially outlawed. This concerned the religion of the druids in particular, which was described as a superstitio vana by Tacitus, and Early Christianity, outlawed as a superstitio Iudaica in AD 80 by Domitian.

Superstition and religion

Greek and Roman polytheists, who modeled their relations with the gods on political and social terms, scorned the man who constantly trembled with fear at the thought of the gods, as a slave feared a cruel and capricious master. Such fear of the gods was what the Romans meant by "superstition" (Veyne 1987, p. 211). 

Diderot's Encyclopédie defines superstition as "any excess of religion in general", and links it specifically with paganism.

In his Prelude on the Babylonian Captivity of the Church, Martin Luther (who called the papacy "that fountain and source of all superstitions") accuses the popes of superstition:

For there was scarce another of the celebrated bishoprics that had so few learned pontiffs; only in violence, intrigue, and superstition has it hitherto surpassed the rest. For the men who occupied the Roman See a thousand years ago differ so vastly from those who have since come into power, that one is compelled to refuse the name of Roman pontiff either to the former or to the latter.

The current Catechism of the Catholic Church considers superstition sinful in the sense that it denotes "a perverse excess of religion", as a demonstrated lack of trust in divine providence (¶ 2110), and a violation of the first of the Ten Commandments. The Catechism is a defense against the accusation that Catholic doctrine is superstitious:

Superstition is a deviation of religious feeling and of the practices this feeling imposes. It can even affect the worship we offer the true God, e.g., when one attributes an importance in some way magical to certain practices otherwise lawful or necessary. To attribute the efficacy of prayers or of sacramental signs to their mere external performance, apart from the interior dispositions that they demand is to fall into superstition. Cf. Matthew 23:16–22 (¶ 2111)

Examples of superstitions and taboos from Weird Tales.

Superstition and psychology

Origins

Behaviorism perspective

In 1948, behavioral psychologist B.F. Skinner published an article in the Journal of Experimental Psychology, in which he described his pigeons exhibiting what appeared to be superstitious behaviour. One pigeon was making turns in its cage, another would swing its head in a pendulum motion, while others also displayed a variety of other behaviours. Because these behaviors were all done ritualistically in an attempt to receive food from a dispenser, even though the dispenser had already been programmed to release food at set time intervals regardless of the pigeons' actions, Skinner believed that the pigeons were trying to influence their feeding schedule by performing these actions. He then extended this as a proposition regarding the nature of superstitious behavior in humans.

Skinner's theory regarding superstition being the nature of the pigeons' behaviour has been challenged by other psychologists such as Staddon and Simmelhag, who theorised an alternative explanation for the pigeons' behaviour.

Despite challenges to Skinner's interpretation of the root of his pigeons' superstitious behaviour, his conception of the reinforcement schedule has been used to explain superstitious behaviour in humans. Originally, in Skinner's animal research, "some pigeons responded up to 10,000 times without reinforcement when they had originally been conditioned on an intermittent reinforcement basis." Compared to the other reinforcement schedules (e.g., fixed ratio, fixed interval), these behaviours were also the most resistant to extinction. This is called the partial reinforcement effect, and this has been used to explain superstitious behaviour in humans. To be more precise, this effect means that, whenever an individual performs an action expecting a reinforcement, and none seems forthcoming, it actually creates a sense of persistence within the individual. This strongly parallels superstitious behaviour in humans because the individual feels that, by continuing this action, reinforcement will happen; or that reinforcement has come at certain times in the past as a result of this action, although not all the time, but this may be one of those times.

Evolutionary/cognitive perspective

From a simpler perspective, natural selection will tend to reinforce a tendency to generate weak associations or heuristics - rules of thumb - that are overgeneralized. If there is a strong survival advantage to making correct associations, then this will outweigh the negatives of making many incorrect, "superstitious" associations. It has also been argued that there may be connections between OCD and superstition. This may be connected to hygiene. 

A recent theory by Jane Risen proposes that superstitions are intuitions that people acknowledge to be wrong, but acquiesce to rather than correct when they arise as the intuitive assessment of a situation. Her theory draws on dual-process models of reasoning. In this view, superstitions are the output of "System 1" reasoning that are not corrected even when caught by "System 2".

Mechanisms

People seem to believe that superstitions influence events by changing the likelihood of currently possible outcomes rather than by creating new possible outcomes. In sporting events, for example, a lucky ritual or object is thought to increase the chance that an athlete will perform at the peak of their ability, rather than increasing their overall ability at that sport. Consequently, people whose goal is to perform well are more likely to rely on "supernatural assistance" - lucky items and rituals - than are people whose goal is to improve their skills and abilities and learn in the same context.

Psychologist Stuart Vyse has pointed out that until about 2010, "[m]ost researchers assumed superstitions were irrational and focused their attentions on discovering why people were superstitious." Vyse went on to describe studies that looked at the relationship between performance and superstitious rituals. Preliminary work has indicated that such rituals can reduce stress and thereby improve performance, but, Vyse has said, "...not because they are superstitious but because they are rituals.... So there is no real magic, but there is a bit of calming magic in performing a ritualistic sequence before attempting a high-pressure activity.... Any old ritual will do."

Occurrence

People tend to attribute events to supernatural causes (in psychological jargon, "external causes") most often under two circumstances.

1. People are more likely to attribute an event to a superstitious cause if it is unlikely than if it is likely. In other words, the more surprising the event, the more likely it is to evoke a supernatural explanation. This is believed to stem from an effectance motivation - a basic desire to exert control over one's environment. When no natural cause can explain a situation, attributing an event to a superstitious cause may give people some sense of control and ability to predict what will happen in their environment.
2. People are more likely to attribute an event to a superstitious cause if it is negative than positive. This is called negative agency bias. Boston Red Sox fans, for instance, attributed the failure of their team to win the world series for 86 years to the curse of the bambino: a curse placed on the team for trading Babe Ruth to the New York Yankees so that the team owner could fund a Broadway musical. When the Red Sox finally won the world series in 2004, however, the team's success was attributed to skill of the team and the rebuilding effort of the new owner and general manager. More commonly, people are more likely to perceive their computer to act according to its own intentions when it malfunctions than functions properly.

Superstition and politics

Ancient Greek historian Polybius in his Histories uses the term superstition explaining that in ancient Rome that belief maintained the cohesion of the empire, operating as an instrumentum regni.

Opposition to superstition

Opposition to superstition was first recorded in ancient Greece, where philosophers such as Protagoras and the Epicureans exhibited agnosticism or aversion to religion and myths, and Plato – especially his Allegory of the Cave – and Aristotle both present their work as parts of a search for truth. 

In the classical era, the existence of gods was actively debated both among philosophers and theologians, and opposition to superstition arose consequently. The poem De rerum natura, written by the Roman poet and philosopher Lucretius further developed the opposition to superstition. Cicero’s work De natura deorum also had a great influence on the development of the modern concept of superstition as well as the word itself. Where Cicero distinguished superstitio and religio, Lucretius used only the term religio. Cicero, for whom superstitio meant “excessive fear of the gods” wrote that “superstitio, non religio, tollenda est ”, which means that only superstition, and not religion, should be abolished. The Roman Empire also made laws condemning those who excited excessive religious fear in others.

During the Middle Ages, the idea of God’s influence on the world’s events went mostly undisputed. Trials by ordeal were quite frequent, even though Frederick II (1194 – 1250 AD) was the first king who explicitly outlawed trials by ordeal as they were considered “irrational”.

The rediscovery of lost classical works (The Renaissance) and scientific advancement led to a steadily increasing disbelief in superstition. A new, more rationalistic lens was beginning to see use in exegesis. Opposition to superstition was central to the Age of Enlightenment. The first philosopher who dared to criticize superstition publicly and in a written form was Baruch Spinoza, who was a key figure in the Age of Enlightenment.

Pinophyta (conifers)

From Wikipedia, the free encyclopedia

Pinophyta Temporal range: Carboniferous – Present PreЄ Є O S D C P T J K Pg N
Conifer forests, though comprising few species, cover vast areas, as in this forest in the Cascade Range of western North America.
Scientific classification
Kingdom:	Plantae
Clade:	Spermatophytes
Division:	Pinophyta
Class:	Pinopsida
Orders and families
Cordaitales † Pinales Pinaceae Araucariaceae Podocarpaceae Sciadopityaceae Cupressaceae Cephalotaxaceae Taxaceae Vojnovskyales † Voltziales †
Synonyms
Coniferophyta Coniferae

The Pinophyta, also known as Coniferophyta or Coniferae, or commonly as conifers, are a division of vascular land plants containing a single extant class, Pinopsida. They are gymnosperms, cone-bearing seed plants. All extant conifers are perennial woody plants with secondary growth. The great majority are trees, though a few are shrubs. Examples include cedars, Douglas firs, cypresses, firs, junipers, kauri, larches, pines, hemlocks, redwoods, spruces, and yews. As of 1998, the division Pinophyta was estimated to contain eight families, 68 genera, and 629 living species.

Although the total number of species is relatively small, conifers are ecologically important. They are the dominant plants over large areas of land, most notably the taiga of the Northern Hemisphere, but also in similar cool climates in mountains further south. Boreal conifers have many wintertime adaptations. The narrow conical shape of northern conifers, and their downward-drooping limbs, help them shed snow. Many of them seasonally alter their biochemistry to make them more resistant to freezing. While tropical rainforests have more biodiversity and turnover, the immense conifer forests of the world represent the largest terrestrial carbon sink. Conifers are of great economic value for softwood lumber and paper production.

Evolution

The narrow conical shape of northern conifers, and their downward-drooping limbs, help them shed snow.

 

The earliest conifers in the fossil record date to the late Carboniferous (Pennsylvanian) period (about 300 million years ago), possibly arising from Cordaites, a genus of seed-bearing Gondwanan plants with cone-like fertile structures. Pinophytes, Cycadophytes, and Ginkgophytes all developed at this time. An important adaptation of these gymnosperms was allowing plants to live without being so dependent on water. Other adaptations are pollen (so fertilisation can occur without water) and the seed, which allows the embryo to be transported and developed elsewhere.

Conifers appear to be one of the taxa that benefited from the Permian–Triassic extinction event, and were the dominant land plants of the Mesozoic era. They were overtaken by the flowering plants, which first appeared in the Cretaceous, and became dominant in the Cenozoic era. Conifers were the main food of herbivorous dinosaurs, and their resins and poisons would have given protection against herbivores. Reproductive features of modern conifers had evolved by the end of the Mesozoic era.

Taxonomy and naming

Conifer is a Latin word, a compound of conus (cone) and ferre (to bear), meaning "the one that bears (a) cone(s)". 

The division name Pinophyta conforms to the rules of the International Code of Nomenclature for algae, fungi, and plants (ICN), which state (Article 16.1) that the names of higher taxa in plants (above the rank of family) are either formed from the name of an included family (usually the most common and/or representative), in this case Pinaceae (the pine family), or are descriptive. A descriptive name in widespread use for the conifers (at whatever rank is chosen) is Coniferae (Art 16 Ex 2). 

According to the ICN, it is possible to use a name formed by replacing the termination -aceae in the name of an included family, in this case preferably Pinaceae, by the appropriate termination, in the case of this division ‑ophyta. Alternatively, "descriptive botanical names" may also be used at any rank above family. Both are allowed. 

This means that if conifers are considered a division, they may be called Pinophyta or Coniferae. As a class they may be called Pinopsida or Coniferae. As an order they may be called Pinales or Coniferae or Coniferales. 

Conifers are the largest and economically most important component group of the gymnosperms, but nevertheless they comprise only one of the four groups. The division Pinophyta consists of just one class, Pinopsida, which includes both living and fossil taxa. Subdivision of the living conifers into two or more orders has been proposed from time to time. The most commonly seen in the past was a split into two orders, Taxales (Taxaceae only) and Pinales (the rest), but recent research into DNA sequences suggests that this interpretation leaves the Pinales without Taxales as paraphyletic, and the latter order is no longer considered distinct. A more accurate subdivision would be to split the class into three orders, Pinales containing only Pinaceae, Araucariales containing Araucariaceae and Podocarpaceae, and Cupressales containing the remaining families (including Taxaceae), but there has not been any significant support for such a split, with the majority of opinion preferring retention of all the families within a single order Pinales, despite their antiquity and diverse morphology.

Phylogeny of the Pinophyta based on cladistic analysis of molecular data.

 

The conifers are now accepted as comprising seven families, with a total of 65–70 genera and 600–630 species (696 accepted names). The seven most distinct families are linked in the box above right and phylogenetic diagram left. In other interpretations, the Cephalotaxaceae may be better included within the Taxaceae, and some authors additionally recognize Phyllocladaceae as distinct from Podocarpaceae (in which it is included here). The family Taxodiaceae is here included in family Cupressaceae, but was widely recognized in the past and can still be found in many field guides. A new classification and linear sequence based on molecular data can be found in an article by Christenhusz et al.

The conifers are an ancient group, with a fossil record extending back about 300 million years to the Paleozoic in the late Carboniferous period; even many of the modern genera are recognizable from fossils 60–120 million years old. Other classes and orders, now long extinct, also occur as fossils, particularly from the late Paleozoic and Mesozoic eras. Fossil conifers included many diverse forms, the most dramatically distinct from modern conifers being some herbaceous conifers with no woody stems. Major fossil orders of conifers or conifer-like plants include the Cordaitales, Vojnovskyales, Voltziales and perhaps also the Czekanowskiales (possibly more closely related to the Ginkgophyta).

Morphology

All living conifers are woody plants, and most are trees, the majority having monopodial growth form (a single, straight trunk with side branches) with strong apical dominance. Many conifers have distinctly scented resin, secreted to protect the tree against insect infestation and fungal infection of wounds. Fossilized resin hardens into amber. The size of mature conifers varies from less than one metre, to over 100 metres. The world's tallest, thickest, largest, and oldest living trees are all conifers. The tallest is a Coast Redwood (Sequoia sempervirens), with a height of 115.55 metres (although one Victorian mountain ash, Eucalyptus regnans, allegedly grew to a height of 140 metres, although the exact dimensions were not confirmed). The thickest, or tree with the greatest trunk diameter, is a Montezuma Cypress (Taxodium mucronatum), 11.42 metres in diameter. The largest tree by three-dimensional volume is a Giant Sequoia (Sequoiadendron giganteum), with a volume 1486.9 cubic metres. The smallest is the pygmy pine (Lepidothamnus laxifolius) of New Zealand, which is seldom taller than 30 cm when mature. The oldest is a Great Basin Bristlecone Pine (Pinus longaeva), 4,700 years old.

Foliage

Pinaceae: needle-like leaves and vegetative buds of Coast Douglas fir (Pseudotsuga menziesii var. menziesii)

 

Araucariaceae: Awl-like leaves of Cook Pine (Araucaria columnaris)

 

In Abies grandis (grand fir), and many other species with spirally arranged leaves, leaf bases are twisted to flatten their arrangement and maximize light capture.

 

Cupressaceae: scale leaves of Lawson's Cypress (Chamaecyparis lawsoniana); scale in mm

 

Since most conifers are evergreens, the leaves of many conifers are long, thin and have a needle-like appearance, but others, including most of the Cupressaceae and some of the Podocarpaceae, have flat, triangular scale-like leaves. Some, notably Agathis in Araucariaceae and Nageia in Podocarpaceae, have broad, flat strap-shaped leaves. Others such as Araucaria columnaris have leaves that are awl-shaped. In the majority of conifers, the leaves are arranged spirally, exceptions being most of Cupressaceae and one genus in Podocarpaceae, where they are arranged in decussate opposite pairs or whorls of 3 (−4). In many species with spirally arranged leaves, such as Abies grandis (pictured), the leaf bases are twisted to present the leaves in a very flat plane for maximum light capture. Leaf size varies from 2 mm in many scale-leaved species, up to 400 mm long in the needles of some pines (e.g. Apache Pine, Pinus engelmannii). The stomata are in lines or patches on the leaves, and can be closed when it is very dry or cold. The leaves are often dark green in colour, which may help absorb a maximum of energy from weak sunshine at high latitudes or under forest canopy shade. Conifers from hotter areas with high sunlight levels (e.g. Turkish Pine Pinus brutia) often have yellower-green leaves, while others (e.g. blue spruce, Picea pungens) have a very strong glaucous wax bloom to reflect ultraviolet light. In the great majority of genera the leaves are evergreen, usually remaining on the plant for several (2–40) years before falling, but five genera (Larix, Pseudolarix, Glyptostrobus, Metasequoia and Taxodium) are deciduous, shedding the leaves in autumn and leafless through the winter. The seedlings of many conifers, including most of the Cupressaceae, and Pinus in Pinaceae, have a distinct juvenile foliage period where the leaves are different, often markedly so, from the typical adult leaves.

Tree ring structure

The internal structure of conifer

 

Tree rings are records of the influence of environmental conditions, their anatomical characteristics record growth rate changes produced by these changing conditions. The microscopic structure of conifer wood consists of two types of cells: parenchyma, which have an oval or polyhedral shape with approximately identical dimensions in three directions, and strongly elongated tracheids. Tracheids make up more than 90% of timber volume. The tracheids of earlywood formed at the beginning of a growing season have large radial sizes and smaller, thinner cell walls. Then, the first tracheids of the transition zone are formed, where the radial size of cells and thickness of their cell walls changes considerably. Finally, the latewood tracheids are formed, with small radial sizes and greater cell wall thickness. This is the basic pattern of the internal cel structure of conifer tree rings.

Reproduction

Most conifers are monoecious, but some are subdioecious or dioecious; all are wind-pollinated. Conifer seeds develop inside a protective cone called a strobilus. The cones take from four months to three years to reach maturity, and vary in size from 2 mm to 600 mm long.

In Pinaceae, Araucariaceae, Sciadopityaceae and most Cupressaceae, the cones are woody, and when mature the scales usually spread open allowing the seeds to fall out and be dispersed by the wind. In some (e.g. firs and cedars), the cones disintegrate to release the seeds, and in others (e.g. the pines that produce pine nuts) the nut-like seeds are dispersed by birds (mainly nutcrackers, and jays), which break up the specially adapted softer cones. Ripe cones may remain on the plant for a varied amount of time before falling to the ground; in some fire-adapted pines, the seeds may be stored in closed cones for up to 60–80 years, being released only when a fire kills the parent tree.

In the families Podocarpaceae, Cephalotaxaceae, Taxaceae, and one Cupressaceae genus (Juniperus), the scales are soft, fleshy, sweet and brightly colored, and are eaten by fruit-eating birds, which then pass the seeds in their droppings. These fleshy scales are (except in Juniperus) known as arils. In some of these conifers (e.g. most Podocarpaceae), the cone consists of several fused scales, while in others (e.g. Taxaceae), the cone is reduced to just one seed scale or (e.g. Cephalotaxaceae) the several scales of a cone develop into individual arils, giving the appearance of a cluster of berries.

The male cones have structures called microsporangia that produce yellowish pollen through meiosis. Pollen is released and carried by the wind to female cones. Pollen grains from living pinophyte species produce pollen tubes, much like those of angiosperms. The gymnosperm male gametophytes (pollen grains) are carried by wind to a female cone and are drawn into a tiny opening on the ovule called the micropyle. It is within the ovule that pollen-germination occurs. From here, a pollen tube seeks out the female gametophyte, which contains archegonia each with an egg, and if successful, fertilization occurs. The resulting zygote develops into an embryo, which along with the female gametophyte (nutritional material for the growing embryo) and its surrounding integument, becomes a seed. Eventually the seed may fall to the ground and, if conditions permit, grow into a new plant.

In forestry, the terminology of flowering plants has commonly though inaccurately been applied to cone-bearing trees as well. The male cone and unfertilized female cone are called male flower and female flower, respectively. After fertilization, the female cone is termed fruit, which undergoes ripening (maturation). 

It was found recently that the pollen of conifers transfers the mitochondrial organelles to the embryo, a sort of meiotic drive that perhaps explains why Pinus and other conifers are so productive, and perhaps also has bearing on (observed?) sex-ratio bias.

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  Pinaceae: unopened female cones of subalpine fir (Abies lasiocarpa)
  
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  Taxaceae: the fleshy aril that surrounds each seed in the European Yew (Taxus baccata) is a highly modified seed cone scale
  
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  Pinaceae: pollen cone of a Japanese Larch (Larix kaempferi)
  

Life cycle

Conifers are heterosporous, generating two different types of spores: male microspores and female megaspores. These spores develop on separate male and female sporophylls on separate male and female cones. In the male cones, microspores are produced from microsporocytes by meiosis. The microspores develop into pollen grains, which are male gametophytes. Large amounts of pollen are released and carried by the wind. Some pollen grains will land on a female cone for pollination. The generative cell in the pollen grain divides into two haploid sperm cells by mitosis leading to the development of the pollen tube. At fertilization, one of the sperm cells unites its haploid nucleus with the haploid nucleus of an egg cell. The female cone develops two ovules, each of which contains haploid megaspores. A megasporocyte is divided by meiosis in each ovule. Each winged pollen grain is a four celled male gametophyte. Three of the four cells break down leaving only a single surviving cell which will develop into a female multicellular gametophyte. The female gametophytes grow to produce two or more archegonia, each of which contains an egg. Upon fertilization, the diploid egg will give rise to the embryo, and a seed is produced. The female cone then opens, releasing the seeds which grow to a young seedling.

1. To fertilize the ovum, the male cone releases pollen that is carried on the wind to the female cone. This is pollination. (Male and female cones usually occur on the same plant.)
2. The pollen fertilizes the female gamete (located in the female cone). Fertilization in some species does not occur until 15 months after pollination.
3. A fertilized female gamete (called a zygote) develops into an embryo.
4. A seed develops which contains the embryo. The seed also contains the integument cells surrounding the embryo. This is an evolutionary characteristic of the Spermatophyta.
5. Mature seed drops out of cone onto the ground.
6. Seed germinates and seedling grows into a mature plant.
7. When the plant is mature, it produces cones and the cycle continues.

Female reproductive cycles

Conifer reproduction is synchronous with seasonal changes in temperate zones. Reproductive development slows to a halt during each winter season, and then resumes each spring. The male strobilus development is completed in a single year. Conifers are classified by three reproductive cycles, namely; 1-, 2-, or 3- . The cycles refers to the completion of female strobilus development from initiation to seed maturation. All three types or reproductive cycles have a long gap in between pollination and fertilization.

One year reproductive cycle:The genera includes Abies, Picea, Cedrus, Pseudotsuga, Tsuga, Keteleeria (Pinaceae) and Cupressus, Thuja, Cryptomeria, Cunninghamia and Sequoia (Cupressaceae). Female strobili are initiated in late summer or fall in a year, then they overwinter. Female strobili emerge followed by pollination in the following spring . Fertilization takes place in summer of the following year, only 3–4 months after pollination. Cones mature and seeds are then shed by the end of that same year. Pollination and fertilization occurs in a single growing season.

Two-year reproductive cycle:The genera includes Widdringtonia, Sequoiadendron (Cupressaceae) and most species of Pinus. Female strobilus initials are formed in late summer or fall then overwinter. It emerges and receives pollen in the first year spring and become conelets. The conelet goes through another winter rest and in the spring of the 2nd year. The Archegonia form in the conelet and fertilization of the archegonia occurs by early summer of the 2nd year, so the pollination-fertilization interval exceeds a year. After fertilization, the conelet is considered an immature cone. Maturation occurs by autumn of the 2nd year, at which time seeds are shed. In summary, the 1-year and the 2-year cycles differ mainly in the duration of the pollination- fertilization interval.

Three-year reproductive cycle: Three of the conifer species are pine species (Pinus pinea, Pinus leiophylla, Pinus torreyana) which have pollination and fertilization events separated by a 2-year interval. Female strobili initiated during late summer or autumn in a year, then overwinter until the following spring. Female strobili emerge then pollination occurs in spring of the 2nd year then the pollinated strobili become conelets in same year (i.e. the second year). The female gametophytes in the conelet develop so slowly that the megaspore does not go through free-nuclear divisions until autumn of the 3rd year. The conelet then overwinters again in the free-nuclear female gametophyte stage. Fertilization takes place by early summer of the 4th year and seeds mature in the cones by autumn of the 4th year.

Tree development

The growth and form of a forest tree are the result of activity in the primary and secondary meristems, influenced by the distribution of photosynthate from its needles and the hormonal gradients controlled by the apical meristems (Fraser et al. 1964). External factors also influence growth and form. 

Fraser recorded the development of a single white spruce tree from 1926 to 1961. Apical growth of the stem was slow from 1926 through 1936 when the tree was competing with herbs and shrubs and probably shaded by larger trees. Lateral branches began to show reduced growth and some were no longer in evidence on the 36-year-old tree. Apical growth totalling about 340 m, 370 m, 420 m, 450 m, 500 m, 600 m, and 600 m was made by the tree in the years 1955 through 1961, respectively. The total number of needles of all ages present on the 36-year-old tree in 1961 was 5.25 million weighing 14.25 kg. In 1961, needles as old as 13 years remained on the tree.The ash weight of needles increased progressively with age from about 4% in first-year needles in 1961 to about 8% in needles 10 years old. In discussing the data obtained from the one 11 m tall white spruce, Fraser et al. (1964) speculated that if the photosynthate used in making apical growth in 1961 was manufactured the previous year, then the 4 million needles that were produced up to 1960 manufactured food for about 600,000 mm of apical growth or 730 g dry weight, over 12 million mm³ of wood for the 1961 annual ring, plus 1 million new needles, in addition to new tissue in branches, bark, and roots in 1960. Added to this would be the photosynthate to produce energy to sustain respiration over this period, an amount estimated to be about 10% of the total annual photosynthate production of a young healthy tree. On this basis, one needle produced food for about 0.19 mg dry weight of apical growth, 3 mm³ wood, one-quarter of a new needle, plus an unknown amount of branch wood, bark and roots. 

The order of priority of photosynthate distribution is probably: first to apical growth and new needle formation, then to buds for the next year's growth, with the cambium in the older parts of the branches receiving sustenance last. In the white spruce studied by Fraser et al. (1964), the needles constituted 17.5% of the over-day weight. Undoubtedly, the proportions change with time.

Seed dispersal mechanism

Wind and animals dispersals are two major mechanisms involved in the dispersal of conifer seeds. Wind bore seed dispersal involves two processes, namely; local neighborhood dispersal (LND) and long- distance dispersal (LDD). Long-distance dispersal distances ranges from 11.9–33.7 kilometres (7.4–20.9 mi) from the source. The bird family, Corvidae is the primary distributor of the conifer seeds. These birds are known to cache 32,000 pine seeds and transport the seeds as far as 12–22 kilometres (7.5–13.7 mi) from the source. The birds store the seeds in the soil at depths of 2–3 centimetres (0.79–1.18 in) under conditions which favor germination.

Invasive species

A Monterey Pine forest in Sydney, Australia.

A number of conifers originally introduced for forestry have become invasive species in parts of New Zealand, including radiata pine (Pinus radiata), lodgepole pine (P. contorta), Douglas fir (Pseudotsuga mensiezii) and European larch (Larix decidua).

In parts of South Africa, maritime pine (Pinus pinaster), patula pine (P. patula) and radiata pine have been declared invasive species. These wilding conifers are a serious environmental issue causing problems for pastoral farming and for conservation.

Radiata pine was introduced to Australia in the 1870s. It is "the dominant tree species in the Australian plantation estate" – so much so that many Australians are concerned by the resulting loss of native wildlife habitat. The species is widely regarded as an environmental weed across southeastern and southwestern Australia  and the removal of individual plants beyond plantations is encouraged.

Predators

At least 20 species of roundheaded borers of the family Cerambycidae feed on the wood of spruce, fir, and hemlock (Rose and Lindquist 1985). Borers rarely bore tunnels in living trees, although when populations are high, adult beetles feed on tender twig bark, and may damage young living trees. One of the most common and widely distributed borer species in North America is the whitespotted sawyer (Monochamus scutellatus). Adults are found in summer on newly fallen or recently felled trees chewing tiny slits in the bark in which they lay eggs. The eggs hatch in about 2 weeks, and the tiny larvae tunnel to the wood and score its surface with their feeding channels. With the onset of cooler weather, they bore into the wood making oval entrance holes and tunnel deeply. Feeding continues the following summer, when larvae occasionally return to the surface of the wood and extend the feeding channels generally in a U-shaped configuration. During this time, small piles of frass extruded by the larvae accumulate under logs. Early in the spring of the second year following egg-laying, the larvae, about 30 mm long, pupate in the tunnel enlargement just below the wood surface. The resulting adults chew their way out in early summer, leaving round exit holes, so completing the usual 2-year life cycle. 

Globosa, a cultivar of Pinus sylvestris, a northern European species, in the North American Red Butte Garden

Cultivation

Conifers – notably Abies (fir), Cedrus, Chamaecyparis lawsoniana (Lawson's cypress), Cupressus (cypress), juniper, Picea (spruce), Pinus (pine), Taxus (yew), Thuja (cedar) – have been the subject of selection for ornamental purposes (for more information see the silviculture page). Plants with unusual growth habits, sizes, and colours are propagated and planted in parks and gardens throughout the world.

Conditions for growth

Conifers can absorb nitrogen in either the ammonium (NH₄⁺) or nitrate (NO₃⁻) form, but the forms are not physiologically equivalent. Form of nitrogen affected both the total amount and relative composition of the soluble nitrogen in white spruce tissues (Durzan and Steward 1967). Ammonium nitrogen was shown to foster arginine and amides and lead to a large increase of free guanidine compounds, whereas in leaves nourished by nitrate as the sole source of nitrogen guanidine compounds were less prominent. Durzan and Steward noted that their results, drawn from determinations made in late summer, did not rule out the occurrence of different interim responses at other times of year. Ammonium nitrogen produced significantly heavier (dry weight) seedlings with higher nitrogen content after 5 weeks (McFee and Stone 1968) than did the same amount of nitrate nitrogen. Swan (1960) found the same effect in 105-day-old white spruce. 

The general short-term effect of nitrogen fertilization on coniferous seedlings is to stimulate shoot growth more so than root growth (Armson and Carman 1961). Over a longer period, root growth is also stimulated. Many nursery managers were long reluctant to apply nitrogenous fertilizers late in the growing season, for fear of increased danger of frost damage to succulent tissues. A presentation at the North American Forest Tree Nursery Soils Workshop at Syracuse in 1980 provided strong contrary evidence: Bob Eastman, President of the Western Maine Forest Nursery Co. stated that for 15 years he has been successful in avoiding winter “burn” to Norway spruce and white spruce in his nursery operation by fertilizing with 50–80 lb/ac (56–90 kg/ha) nitrogen in September, whereas previously winter burn had been experienced annually, often severely. Eastman also stated that the overwintering storage capacity of stock thus treated was much improved (Eastman 1980).

The concentrations of nutrient in plant tissues depend on many factors, including growing conditions. Interpretation of concentrations determined by analysis is easy only when a nutrient occurs in excessively low or occasionally excessively high concentration. Values are influenced by environmental factors and interactions among the 16 nutrient elements known to be essential to plants, 13 of which are obtained from the soil, including nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur, all used in relatively large amounts (Buckman and Brady 1969). Nutrient concentrations in conifers also vary with season, age and kind of tissue sampled, and analytical technique. The ranges of concentrations occurring in well-grown plants provide a useful guide by which to assess the adequacy of particular nutrients, and the ratios among the major nutrients are helpful guides to nutritional imbalances.

Economic importance

The softwood derived from conifers is of great economic value, providing about 45% of the world’s annual lumber production. Other uses of the timber include the production of paper and plastic from chemically treated wood pulp. Some conifers also provide foods such as pine nuts and Juniper berries, the latter used to flavor gin.