For other structures in plants called cones, seeStrobilus.
A mature femalebig-cone pine (Pinus coulteri) cone, the heaviest pine cone
Aconifer cone, or in formalbotanical usage astrobilus,pl.:strobili, is a seed-bearing organ ongymnosperm plants, especially inconifers andcycads. They are usually woody and variously conic, cylindrical, ovoid, to globular, and have scales andbracts arranged around a central axis, but can be fleshy andberry-like. The cones ofPinophyta (conifer clade) contain thereproductive structures. The woody cone is the female cone, which producesseeds. The male cone, which producespollen, is usuallyephemeral and much less conspicuous even at full maturity. The name 'cone' derives from Greekkonos (pine cone), which also gave name to the geometriccone. The individual plates of a cone are known asscales. In conifers where the cone develops over more than one year (such aspines), the first year's growth of a seed scale on the cone, showing up as a protuberance at the end of the two-year-old scale, is called anumbo, while the second year's growth is called theapophysis.[1]
The male cone (microstrobilus orpollen cone) is structurally similar across all conifers, differing only in small ways (mostly in scale arrangement) from species to species. Extending out from a central axis aremicrosporophylls (modified leaves). Under each microsporophyll is one or severalmicrosporangia (pollen sacs).[citation needed]
The female cone (megastrobilus,seed cone, orovulate cone) containsovules which when fertilized by pollen become seeds. The female cone structure varies more markedly between the different conifer families and is often crucial for the identification of many species of conifers.[citation needed]
Members of thepine family have cones that are imbricate (that is, with scales overlapping each other like fish scales). These cones, especially the woody female cones, are considered the "archetypal" tree cones. The female cone has two types of scale:bract scale and seed scale (or ovuliferous scale), onesubtended by each bract scale, derived from a highly modifiedbranchlet. On the upper-side base of each seed scale are two ovules that develop into seeds after fertilization by pollen grains. The bract scales develop first and are conspicuous at the time of pollination; the seed scales develop later to enclose and protect the seeds, with the bract scales often not growing further. The scales open temporarily to receive pollen, then close during fertilization and maturation, and re-open at maturity to allow the seed to escape. Maturation takes 6–8 months from pollination in most Pinaceae genera, but 12 months in cedars and 18–24 months (rarely more) in most pines. The cones open either by the seed scales flexing back when they dry out, or (in firs, cedars andgolden larch) by the cones disintegrating with the seed scales falling off. The cones are conic,cylindrical orovoid (egg-shaped), and small to very large, from 2–60 cm long and 1–20 cm broad.[citation needed]
After ripening, the opening of non-serotinous pine cones is associated with their moisture content—cones are open when dry and closed when wet.[2] This assures that the small, windborne seeds will be dispersed during relatively dry weather, and thus the distance traveled from the parent tree will be enhanced. A pine cone goes through many cycles of opening and closing during its life span.[3]
Anatomy of aScots pine (Pinus sylvestris) female strobilus.
Members of theAraucariaceae (Araucaria,Agathis,Wollemia) have the bract and seed scales fully fused and have only one ovule on each scale. The cones are spherical or nearly so, 5–30 cm diameter, and mature in 18 months. For most species they disintegrate at maturity to release the seeds, although in some such asAraucaria bidwillii, the cone weighing up to 10 kilograms (22 lb) is shed intact. InAgathis, the seeds are winged and separate readily from the seed scale, but in the other two genera, the seed is wingless and fused to the scale.[citation needed]
The cones of thePodocarpaceae are similar in function, though not in development, to those of the Taxaceae (q.v. below), being berry-like with the scales highly modified, evolved to attract birds into dispersing the seeds. In most of the genera, two to ten or more scales are fused together into a usually swollen, brightly coloured, soft, edible fleshyaril. Usually, only one or two scales at the apex of the cone are fertile, each bearing a single wingless seed, but inSaxegothaea several scales may be fertile. The fleshy scale complex is 0.5–3 cm long, and the seeds 4–10 mm long. In some genera (e.g.Prumnopitys), the scales are minute and not fleshy, but the seed coat develops a fleshy layer instead, the cone having the appearance of one to three smallplums on a central stem. The seeds have a hard coat evolved to resist digestion in the bird's stomach.[citation needed]
Members of thecypress family (cypresses,arborvitae,junipers,redwoods, etc.) differ in that the bract and seed scales are fully fused, with the bract visible as no more than a small lump or spine on the scale. The botanical termgalbulus (plural galbuli; from theLatin for a cypress cone) is sometimes used instead of strobilus for members of this family. The female cones have one to 20 ovules on each scale. They often have peltate scales, as opposed to the imbricate cones described above, though some have imbricate scales. The cones are usually small, 0.3–6 cm or1⁄8–2+3⁄8 inches long, and often spherical or nearly so, like those ofNootka cypress, while others, such aswestern redcedar andCalifornia incense-cedar, are narrow. The scales are arranged either spirally, or in decussate whorls of two (opposite pairs) or three, rarely four. The genera with spiral scale arrangement were often treated in a separate family (Taxodiaceae) in the past. In most of the genera, the cones are woody and the seeds have two narrow wings (one along each side of the seed), but in three genera (Platycladus,Microbiota andJuniperus), the seeds are wingless, and inJuniperus, the cones are fleshy andberry-like (known asgalbuli).[citation needed]
The cones and seeds ofSciadopitys (the only member of the family) are similar to those of some Cupressaceae, but larger, 6–11 cm long; the scales are imbricate and spirally arranged, and have 5–9 ovules on each scale.[citation needed]
Members of theyew family and the closely relatedCephalotaxaceae have the most highly modified cones of any conifer. There is only one scale in the female cone, with a single poisonous ovule. The scale develops into a soft, brightly coloured sweet, juicy, berry-like aril which partly encloses the deadly seed. The seed alone is poisonous. The whole 'berry' with the seed is eaten by birds, which digest the sugar-rich scale and pass the hard seed undamaged in their droppings, so dispersing the seed far from the parent plant.[citation needed]
Welwitschia is unique cone-bearing plant is not considered a conifer but belongs in the orderWelwitschiales.Welwitschia mirabilis is often called aliving fossil[4] and is the only species in its genus, which is the only genus in its family, which is the only family in its order. The male cones are on male plants, and female cones on female plants. After emergence of the twocotyledons, it sets only two more leaves. Those two leaves then continue to grow longer from their base. This allows it great drought tolerance, which is likely why it has survived in the desert ofNamibia, while all other representatives from its order are extinct.[5]
Most conifer species aremonoecious, with male and female cones occur on the same plant (tree orshrub), with female usually on the higher branches towards the top of the plant. This distribution is thought to improve chances ofcross-fertilization, as pollen is unlikely to be blown vertically upward within the crown of one plant, but can drift slowly upward in the wind, blowing from low on one plant to higher on another plant. In some conifers, male cones additionally often grow clustered in large numbers together, while female cones are more often produced singly or in only small clusters. Some, such asAraucaria araucana andTaxus baccata, aredioecious, with the male and female cones usually on separate trees, but even in normally dioecious species, scattered individuals may produce cones of both sexes, or change which sex cones they produce over time.[1] Some pines, notablyPinus discolor, are subdioecious, with individuals producing cones of both sexes, but with each tree producing either predominantly male, or predominantly female, cones, and only a few of the other sex.[6][7]
A characteristic arrangement of pines is that the male cones are located at the base of the branch, while the female at the tip (of the same or a different branchlet). However, in larches and cedars, both types of cones are always at the tips of short shoots, while both sexes of fir cones are always from side buds, never terminal. There is also some diversity in bearing in Cupressaceae. SomeCupressus for instance, have little or no differentiation in the positions of male and female cones.[citation needed]
Cone crop potential can be predicted in various ways. An early indication of a potential crop can be a period of abnormally hot, dry weather at the time of bud differentiation, particularly if the current and preceding cone crops have been poor.[8] Estimates of cone crop potential can be made by counting female reproductive buds in fall or winter, and an experienced observer can detect the subtle morphological differences and distinguish between reproductive buds and vegetative buds.[9]
White spruce seed collection is expensive, and collection from cone caches ofred squirrels is probably the cheapest method. The viability of seed from cached cones does not vary during current caching, but viability drops essentially to zero after being in caches for 1 or 2 years.[10] Collection of cones in seed orchards has been facilitated by the counter-intuitive technique of "topping" and collection of cones from the severed crown tops at one-third the cost of collection from untopped trees and without decreasing cone production.[11][12]
Because of their widespread occurrence, conifer cones have been a traditional part of thearts and crafts of cultures where conifers are common. Examples of their use includes seasonal wreaths and decorations, fire starters, bird feeders, toys, etc.[13] A derivation of theimpossible bottlemechanical puzzle takes advantage of the fact that pine cones open and close based on their level of dryness. In constructing a display, a closed, damp cone of suitable size is inserted into a narrow-mouthed bottle and allowed to open upon drying.[14]
Cone cows are traditional homemade toys, made by children using material found in nature. The most common design is a spruce or pine cone with sticks ormatches for legs, which can easily be attached by forcing them between the cone scales. Playing with cone cows often includes building an animal enclosure from sticks. For the most part, cone cows have been displaced by manufactured toys, at least in affluent countries, but the creation of cone cows still enjoys some popularity as an outdoor activity for children. Cone cows are a part of children's culture inFinland where they are known askäpylehmä andSweden where they are known askottkor (cone animals).[citation needed]
In Sweden, a video game was released in which the player may build virtual cone cows.[15] Swedish artistLasse Åberg has created artwork with cone cows, which has been included in analphabet book[16] and featured on a Swedishpostage stamp among other classic toys.[17][18]
Cones are used as decorative elements in architecture such as on top of the posts surroundingKoper'sDa Ponte Fountain, the central element of theFontana della Pigna inRome, or a bronze cone in the narthex of theAachen Cathedral. Cones are occasionally used as a charge inheraldic coats of arms. In some parts ofRussia andGeorgia, immature pine cones are harvested in late spring and boiled to make sweetpreserves.[19]
Thepineal gland is named after the pine cone.[20] Pine cones were also used as symbols of fertility in ancient Assyrian art. In Christian symbolism, they are closely related to thetree of life.[21]
^A. Lewington & E. Parker (1999).Ancient Trees: Trees that Live for a Thousand Years. Collins & Brown Ltd.ISBN1-85585-704-9.
^McCormick, Jack; Andresen, John W. (1963). "A Subdioecioius Population of Pinus cembroides in Southeast Arizona".Ohio Journal of Science.63 (4):159–163.
^Slayton, S.H. 1969. A new technique for cone collection. USDA, For. Serv., Tree Plant. Notes 20(3):13. (Cited in Nienstaedt and Zasada 1990).
^Nienstaedt, H. 1981. Top pruning white spruce seed orchard grafts does not reduce cone production. USDA, For. Serv., Tree Plant. Notes 32(2):9–13. (Cited in Coates et al. 1994).
^Posten.se press releaseArchived 2010-09-13 at theWayback Machine "Motives include [..] life in the countryside, which shows both the cone cow, a doll in a traditional outfit, and a horse and carriage toy"
^Livet på landet image of the stamp from the official postal site
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