Conifer cone

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A mature female Coulter pine (Pinus coulteri) cone, the heaviest pine cone Pinus coulteri MHNT Cone.jpg
A mature female Coulter pine (Pinus coulteri) cone, the heaviest pine cone
Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca) young female cone Pseudotsuga menziesii var. glauca young female cone - Keila.jpg
Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca) young female cone
Immature male or pollen cones of Rocky Mountain ponderosa pine. (Pinus ponderosa var. scopulorum) Pinus ponderosa scopulorum pollen cones.jpg
Immature male or pollen cones of Rocky Mountain ponderosa pine. (Pinus ponderosa var. scopulorum)

A conifer cone or pinecone ( strobilus , pl.: strobili in formal botanical usage) is a seed-bearing organ on gymnosperm plants. It is usually woody, ovoid to globular, including scales and bracts arranged around a central axis, especially in conifers and cycads. The cone of Pinophyta (conifer clade) contains the reproductive structures. The woody cone is the female cone, which produces plants. The male cone, which produces pollen, is usually herbaceous and much less conspicuous even at full maturity. The name "cone" derives from Greek konos (pine cone), which also gave name to the geometric cone. The individual plates of a cone are known as scales. The umbo of a conifer cone refers to 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.[ citation needed ]

Contents

The male cone (microstrobili or pollen 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 are microsporophylls (modified leaves). Under each microsporophyll is one or several microsporangia (pollen sacs).

The female cone (megastrobilus, seed cone, or ovulate cone) contains ovules 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.

Female cone of the conifer families

Pinaceae cones

Anatomy of Pinus sylvestris female strobilus. Pinus sylvestris female strobilus and cone en.svg
Anatomy of Pinus sylvestris female strobilus.
Young cones of a blue spruce Picea Pungens Young Cones.jpg
Young cones of a blue spruce

The members of the pine family (pines, spruces, firs, cedars, larches, etc.) have cones that are imbricate (that is, with scales overlapping each other like fish scales). These pine cones, especially the woody female cones, are considered the "archetypal" tree cones.

Image of a young pine cone center Young Pine Cone Center.jpg
Image of a young pine cone center

The female cone has two types of scale: the bract scales, and the seed scales (or ovuliferous scales), one subtended by each bract scale, derived from a highly modified branchlet. 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 then re-open again 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 and golden larch) by the cones disintegrating with the seed scales falling off. The cones are conic, cylindrical or ovoid (egg-shaped), and small to very large, from 2–60 cm long and 1–20 cm broad.

After ripening, the opening of non-serotinous pine cones is associated with their moisture content—cones are open when dry and closed when wet. [1] 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 will go through many cycles of opening and closing during its life span, even after seed dispersal is complete. [2] This process occurs with older cones while attached to branches and even after the older cones have fallen to the forest floor. The condition of fallen pine cones is a crude indication of the forest floor's moisture content, which is an important indication of wildfire risk. Closed cones indicate damp conditions while open cones indicate the forest floor is dry.

As a result of this, pine cones have often been used by people in temperate climates to predict dry and wet weather, usually hanging a harvested pine cone from some string outside to measure the humidity of the air.

Araucariaceae cones

Araucaria angustifolia cones and nuts Pinhas.jpg
Araucaria angustifolia cones and nuts

Members of the Araucariaceae ( 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, and large to very large, 5–30 cm diameter, and mature in 18 months; at maturity, they disintegrate to release the seeds. In Agathis, 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.

Podocarpaceae cones

Berry-like Podocarpus cone Podocarpus macrophyllus (seed s3).jpg
Berry-like Podocarpus cone

The cones of the Podocarpaceae 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 fleshy aril. Usually, only one or two scales at the apex of the cone are fertile, each bearing a single wingless seed, but in Saxegothaea 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 small plums on a central stem. The seeds have a hard coat evolved to resist digestion in the bird's stomach.

Cupressaceae cones

Giant sequoia cones Sequoiadendron giganteum MHNT.BOT.2004.0.191.jpg
Giant sequoia cones

Members of the cypress 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 term galbulus (plural galbuli; from the Latin 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 or 182+38 inches long, and often spherical or nearly so, like those of Nootka cypress, while others, such as western redcedar and California 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 and Juniperus ), the seeds are wingless, and in Juniperus, the cones are fleshy and berry-like (known as galbuli).

Sciadopityaceae cones

The cones and seeds of Sciadopitys (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.

Taxaceae and Cephalotaxaceae cones

Berry-like yew cone Taxus baccata MHNT.jpg
Berry-like yew cone

Members of the yew family and the closely related Cephalotaxaceae 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.

Welwitschiaceae cones

Welwitschia is unique cone-bearing plant is not considered a conifer, but belongs in the Order Welwitschiales. Welwitschia mirabilis is often called a living fossil 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 two cotyledons, it sets only two more leaves. Those two leaves then continue to grow longer from their base, much like fingernails. This allows it great drought tolerance, which is likely why it has survived in the desert of Namibia, while all other representatives from its order are now extinct.

Location and distribution

Male cone of cedar of Lebanon Male cone of Cedar of Lebanon.JPG
Male cone of cedar of Lebanon
Larch cone with unusual branch growth from tip Larch with unusual terminal branch.JPG
Larch cone with unusual branch growth from tip

For most species found in Australia, male and female cones occur on the same plant (tree or shrub), with female usually on the higher branches towards the top of the plant. This distribution is thought to improve chances of cross-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.

A further 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. Some, Cupressus for instance, have little or no differentiation in the positions of male and female cones.

Cone crops

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 (Nienstaedt and Zasada 1990). [3] 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 (Eis 1967b). [4]

White spruce seed collection is expensive, and collection from cone caches of red 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 (Wagg 1964). [5]

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 (Slayton 1969, Nienstaedt 1981). [6] [7]

Pseudocones

Developing pineapple pseudocone galls on Norway spruce. Developing Pineapple Gall.JPG
Developing pineapple pseudocone galls on Norway spruce.
Pseudocone on Sitka spruce Sitka Spruce with Pineapple Gall.JPG
Pseudocone on Sitka spruce

Norway and Sitka spruce are prone to the formation of pineapple gall pseudocones caused by the woolly aphid, Adelges abietis. These are not cones, although they closely resemble them.

While alder trees are not conifers, their mature seed bearing structures closely resemble cones.

Cultural uses

Home-made spruce cone cow Pine cone cow on grass.jpg
Home-made spruce cone cow
Cone in the coat of arms of Sarrant. Blason ville fr Sarrant (Gers).svg
Cone in the coat of arms of Sarrant.

Because of their widespread occurrence, conifer cones have been a traditional part of the arts and crafts of cultures where conifers are common. Examples of their use includes seasonal wreaths and decorations, fire starters, bird feeders, toys, etc. [8] An intriguing derivation of the impossible bottle mechanical puzzle takes advantage of the fact that pine cones open and close based on their level of dryness. In constructing the pine cone in the bottle display, a closed, damp cone of suitable size is inserted into a narrow-mouthed bottle and allowed to open upon drying. [9]

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 or matches 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.

Four cones in the coat of arms of Sulkava. Sulkava.vaakuna.svg
Four cones in the coat of arms of Sulkava.

Cone cows are a part of children's culture in Finland where they are known as Käpylehmä (plural: Käpylehmät) and Sweden where they are known as kottkor or kottdjur (cone animals). Schools and other institutions teach children how to make cone cows as part of outdoors education on nature and history.

In Finland there is a fairground with cone cow sculptures large enough for children to ride on. In Sweden, a video game was released in which the player may build virtual cone cows. [10] Swedish artist Lasse Åberg has created artwork with cone cows, which has been included in an alphabet book [11] and featured on a Swedish postage stamp among other classic toys. [12] [13]

The bronze pine cone in Aachen Cathedral Aachen - Pine cone.jpg
The bronze pine cone in Aachen Cathedral
Pine cone statue from the Cortile della Pigna of the Vatican Museums Cortile della Pigna pine cone 2.jpg
Pine cone statue from the Cortile della Pigna of the Vatican Museums
Da Ponte fountain in Koper Koper fountain.JPG
Da Ponte fountain in Koper

Cones are also used as decorative elements in architecture such as on top of the posts surrounding Koper's Da Ponte Fountain, the central element of the Fontana della Pigna in Rome or a bronze cone in the narthex of the Aachen Cathedral. Cones are also occasionally used as a charge in heraldic coats of arms.

In some parts of Russia and Georgia, immature pine cones are harvested in late spring and boiled to make sweet preserves. [14]

Symbolism

Coat of arms of the Parthon de Von family featuring three pine cones Armes de la famille Parthon de Von.svg
Coat of arms of the Parthon de Von family featuring three pine cones

The pineal gland is named after the pine cone. [15] Pine cones were also used as symbols of fertility in ancient Assyrian art. In Christian symbolism, they are closely related to the tree of life. [16]

See also

Visualisation of a Cupressus cone by micro computed tomography

Related Research Articles

<i>Cedrus</i> Genus of plants (coniferous trees)

Cedrus, with the common English name cedar, is a genus of coniferous trees in the plant family Pinaceae. They are native to the mountains of the western Himalayas and the Mediterranean region, occurring at altitudes of 1,500–3,200 m in the Himalayas and 1,000–2,200 m in the Mediterranean.

<span class="mw-page-title-main">Conifer</span> Group of cone-bearing seed plants

Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta, also known as Coniferophyta or Coniferae. The division contains a single extant class, Pinopsida. 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. The division Pinophyta contains seven families, 60 to 65 genera, and more than 600 living species.

<span class="mw-page-title-main">Larch</span> Genus of deciduous conifers in the family Pinaceae

Larches are deciduous conifers in the genus Larix, of the family Pinaceae. Growing from 20 to 45 metres tall, they are native to the cooler regions of the northern hemisphere, where they are found in lowland forests in the high latitudes, and high in mountains further south. Larches are among the dominant plants in the boreal forests of Siberia and Canada. Although they are conifers, larches are deciduous trees that lose their needles in the autumn.

<span class="mw-page-title-main">Juniper</span> Genus of plants

Junipers are coniferous trees and shrubs in the genus Juniperus of the cypress family Cupressaceae. Depending on the taxonomy, between 50 and 67 species of junipers are widely distributed throughout the Northern Hemisphere, from the Arctic, south to tropical Africa, throughout parts of western, central and southern Asia, east to eastern Tibet in the Old World, and in the mountains of Central America. The highest-known juniper forest occurs at an altitude of 4,900 metres (16,100 ft) in southeastern Tibet and the northern Himalayas, creating one of the highest tree lines on earth.

<span class="mw-page-title-main">Taxaceae</span> Family of conifers

Taxaceae, commonly called the yew family, is a coniferous family which includes six extant and two extinct genera, and about 30 species of plants, or in older interpretations three genera and 7 to 12 species.

<span class="mw-page-title-main">Gymnosperm</span> Clade of non-flowering, naked-seeded vascular plants

The gymnosperms are a group of seed-producing plants that includes conifers, cycads, Ginkgo, and gnetophytes, forming the clade Gymnospermae. The term gymnosperm comes from the composite word in Greek: γυμνόσπερμος, literally meaning 'naked seeds'. The name is based on the unenclosed condition of their seeds. The non-encased condition of their seeds contrasts with the seeds and ovules of flowering plants (angiosperms), which are enclosed within an ovary. Gymnosperm seeds develop either on the surface of scales or leaves, which are often modified to form cones, or on their own as in yew, Torreya, Ginkgo. Gymnosperm lifecycles involve alternation of generations. They have a dominant diploid sporophyte phase and a reduced haploid gametophyte phase which is dependent on the sporophytic phase. The term "gymnosperm" is often used in paleobotany to refer to all non-angiosperm seed plants. In that case, to specify the modern monophyletic group of gymnosperms, the term Acrogymnospermae is sometimes used.

<span class="mw-page-title-main">Pinaceae</span> Family of conifers

The Pinaceae, or pine family, are conifer trees or shrubs, including many of the well-known conifers of commercial importance such as cedars, firs, hemlocks, piñons, larches, pines and spruces. The family is included in the order Pinales, formerly known as Coniferales. Pinaceae are supported as monophyletic by their protein-type sieve cell plastids, pattern of proembryogeny, and lack of bioflavonoids. They are the largest extant conifer family in species diversity, with between 220 and 250 species in 11 genera, and the second-largest in geographical range, found in most of the Northern Hemisphere, with the majority of the species in temperate climates, but ranging from subarctic to tropical. The family often forms the dominant component of boreal, coastal, and montane forests. One species, Pinus merkusii, grows just south of the equator in Southeast Asia. Major centres of diversity are found in the mountains of southwest China, Mexico, central Japan, and California.

<span class="mw-page-title-main">Cupressaceae</span> Cypress family of conifers

Cupressaceae is a conifer family, the cypress, with worldwide distribution. The family includes 27–30 genera, which include the junipers and redwoods, with about 130–140 species in total. They are monoecious, subdioecious or (rarely) dioecious trees and shrubs up to 116 m (381 ft) tall. The bark of mature trees is commonly orange- to red-brown and of stringy texture, often flaking or peeling in vertical strips, but smooth, scaly or hard and square-cracked in some species.

<i>Platycladus</i> Genus of conifers

Platycladus is a monotypic genus of evergreen coniferous trees in the cypress family Cupressaceae, containing only one species, Platycladus orientalis, also known as Chinese thuja, Oriental arborvitae, Chinese arborvitae, biota or Oriental thuja. It is native to northeastern parts of East Asia and North Asia, but is also now naturalised as an introduced species in other regions of the Asian continent.

<i>Abies balsamea</i> Species of conifer tree

Abies balsamea or balsam fir is a North American fir, native to most of eastern and central Canada and the northeastern United States.

<i>Podocarpus</i> Genus of conifers in the family Podocarpaceae

Podocarpus is a genus of conifers, the most numerous and widely distributed of the podocarp family, the Podocarpaceae. The name comes from Greek πούς + καρπός. Podocarpus species are evergreen shrubs or trees, usually from 1 to 25 m tall, known to reach 40 m (130 ft) at times. The cones have two to five fused cone scales, which form a fleshy, berry-like, brightly coloured receptacle at maturity. The fleshy cones attract birds, which then eat the cones and disperse the seeds in their droppings. About 97 to 107 species are placed in the genus depending on the circumscription of the species.

<i>Nageia</i> Genus of conifers in the family Podocarpaceae

Nageia is a genus of conifers belonging to the podocarp family Podocarpaceae. Nageia includes evergreen shrubs and trees, from one to 54 meters in height. A 2009 treatment of the genus recognized five species. Some authors consider Nageia formosensis to be a separate species from Nageia nagi, thus recognizing six species. The podocarp genera have been reshuffled by various botanists. Most recently, several species formerly classed as Nageia were moved to the new genus Retrophyllum, while Nageia falcata and Nageia mannii were moved to the new genus Afrocarpus.

<i>Afrocarpus</i> Genus of conifers

Afrocarpus is a genus of conifers of the family Podocarpaceae. Two to six species are recognized. They are evergreen trees native to Africa. Afrocarpus was designated a genus in 1989, when several species formerly classified in Podocarpus and Nageia were reclassified.

<span class="mw-page-title-main">Syconium</span> Technical name for a type of plant fruit

Syconium is the type of inflorescence borne by figs, formed by an enlarged, fleshy, hollow receptacle with multiple ovaries on the inside surface. In essence, it is really a fleshy stem with a number of flowers, so it is considered both a multiple and accessory fruit.

<span class="mw-page-title-main">Bennettitales</span> Extinct order of seed plants

Bennettitales is an extinct order of seed plants that first appeared in the Permian period and became extinct in most areas toward the end of the Cretaceous. Bennettitales were amongst the most common seed plants of the Mesozoic, and had morphologies including shrub and cycad-like forms. The foliage of bennettitaleans is superficially nearly indistinguishable from that of cycads, but they are distinguished from cycads by their more complex flower-like reproductive organs, at least some of which were likely pollinated by insects.

<i>Widdringtonia</i> Genus of conifers

Widdringtonia is a genus of coniferous trees in the Cupressaceae. The name was Austrian botanist Stephan Endlicher's way of honouring an early expert on the coniferous forests of Spain, Capt. Samuel Edward Widdrington (1787–1856). There are four species, all native to southern Africa, where they are known as cedars or African cypresses.

<i>Retrophyllum</i> Genus of conifers

Retrophyllum is a genus of conifers in the family Podocarpaceae. It contains five generally recognized extant species with a disjunct distribution in the Southern Hemisphere, found in Papuasia and also in South America. Retrophyllum are evergreen trees typically occurring in tropical rainforests and cloud forests.

A strobilus is a structure present on many land plant species consisting of sporangia-bearing structures densely aggregated along a stem. Strobili are often called cones, but some botanists restrict the use of the term cone to the woody seed strobili of conifers. Strobili are characterized by a central axis surrounded by spirally arranged or decussate structures that may be modified leaves or modified stems.

<i>Lepidothamnus laxifolius</i> Species of conifer

Lepidothamnus laxifolius, commonly known as the pygmy pine or mountain rimu, is a species of conifer in the family Podocarpaceae. It is endemic to New Zealand, where it is found in the North Island, the South Island and on Stewart Island.

Retrophyllum vitiense is a species of conifer in the family Podocarpaceae. It is a large evergreen rainforest emergent tree native to Fiji, Vanuatu, and the Santa Cruz Islands.

References

  1. Dawson, Colin; Vincent, Julian F. V.; Rocca, Anne-Marie. 1997. How pine cones open. Nature 390: 668.
  2. "Ask a Scientist: Pine Cone Wet and Dry". Newton.dep.anl.gov. Archived from the original on 2015-02-26. Retrieved 2013-08-30.
  3. Nienstaedt, Hans; Zasada, John C. (1990). "Picea glauca". In Burns, Russell M.; Honkala, Barbara H. (eds.). Conifers. Silvics of North America. Washington, D.C.: United States Forest Service (USFS), United States Department of Agriculture (USDA). Vol. 1 via Southern Research Station.
  4. Eis, S. 1967b. Cone crops of white and black spruce are predictable. For. Chron. 43(3):247–252.
  5. Wagg, J.W.B. 1964. Viability of white spruce seed from squirrel-cut cones. For. Chron. 40(1):98–110.
  6. 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).
  7. 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).
  8. "Pine Cone Craft Projects". Familycrafts.about.com. 2013-08-23. Archived from the original on 2013-05-11. Retrieved 2013-08-30.
  9. zupperzipper (2008-07-13). "Pine Cone in the Bottle Display". Instructables. Retrieved 2013-08-30.
  10. Kapsyljakt med Anki och Pytte review "You build cone cows"
  11. Åbergs ABC [ permanent dead link ] "a little book about cone cows, small fears, swarming helicopters and such"
  12. Posten.se press release Archived 2010-09-13 at the Wayback 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"
  13. Livet på landet image of the stamp from the official postal site
  14. "Pine Cone Preserves". Atlas Obscura.
  15. "Pineal (as an adjective)". Online Etymology Dictionary, Douglas Harper. 2018. Retrieved 27 October 2018.
  16. The Continuum Encyclopedia of Symbols by Udo Becker (2000) Page 234