Hubbry Logo
PyrenaPyrenaMain
Open search
Pyrena
Community hub
Pyrena
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Contribute something
Pyrena
Pyrena
Pyrena
View on Wikipedia
from Wikipedia
Diagram of a typical drupe, in this case a peach, illustrating the layers of both the fruit and the seed; the pyrene is the hardened endocarp which encloses the seed

A pyrena (/paɪˈriːnə/) or pyrene, commonly called a pit or stone, is the fruitstone within a drupe or drupelet produced by the ossification of the endocarp or lining of the fruit.[1] It consists of a hard endocarp tissue surrounding one or more seeds (also called the "kernel").[2][3] The hardened endocarp which constitutes the pyrene provides a protective physical barrier around the seed, shielding it from pathogens and herbivory.[4]

While many drupes are monopyrenous, containing only one pyrene, pome-type fruit with a hard, stony (rather than leathery) endocarp are typically polypyrenous drupes, containing multiple pyrenes.[5]

Development

[edit]

The hardening of the endocarp of a developing drupe occurs via secondary cell wall formation and lignification.[4] The biopolymer lignin, also found in wood, provides a structure within secondary cell walls which supports the polymerisation of cellulose and hemicellulose; together these polymers provide the endocarp with tensile strength and stiffness.[4] Further hardening occurs during the biomineralisation of the endocarp. The biomineralisation of pyrenes during the life of the plant can aid the preservation of fruit remains in archaeological findings.[6][7]

[edit]
  • Cross-section of a peach, a monopyrenous drupe, cut to reveal the pyrene inside
    Cross-section of a peach, a monopyrenous drupe, cut to reveal the pyrene inside
  • Pyrene of a peach dissected to reveal a single seed inside
    Pyrene of a peach dissected to reveal a single seed inside
  • Pyrenes extracted from a single fruit of Crataegus punctata, a polypyrenous drupe
    Pyrenes extracted from a single fruit of Crataegus punctata, a polypyrenous drupe
  • X-ray of a pyrene of Elaeocarpus ganitrus revealing 10 seed-bearing locules inside; the number of locules in E. ganitrus pyrenes is variable between individual fruits
    X-ray of a pyrene of Elaeocarpus ganitrus revealing 10 seed-bearing locules inside; the number of locules in E. ganitrus pyrenes is variable between individual fruits

See also

[edit]

References

[edit]

Bibliography

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Pyrena

View on Grokipedia
from Grokipedia
A pyrena (plural: pyrenae), also known as a pyrene, is a botanical term for the hard, stony structure within a drupe or drupelet, consisting of the ossified endocarp that encloses and protects the seed. It is commonly called the pit or stone of the fruit, distinguishing it from the fleshy outer layers. The term originates from New Latin pyrena, derived from Ancient Greek pyrēn, meaning "fruit stone." In botanical classification, pyrenae are integral to drupaceous fruits, where the endocarp hardens to form this protective nutlet, often containing a single seed. Examples include the single pyrena in stone fruits like cherries (Prunus avium) and peaches (Prunus persica), where it safeguards the kernel amid the edible mesocarp. In aggregate fruits, such as raspberries (Rubus idaeus) and blackberries (Rubus fruticosus), multiple pyrenae occur, one in each drupelet that collectively forms the berry-like structure. This adaptation aids seed dispersal by animals, as the tough pyrena resists digestion while the surrounding flesh attracts consumers. Pyrenae vary in number and structure across species; for instance, some drupes contain 2–5 pyrenae, as seen in certain Rubiaceae or Ericaceae plants.

Etymology and Terminology

Origin of the Term

The term "pyrena" derives from New Latin pyrena, which in turn originates from the pyrēn (πυρήν), signifying "" or "kernel," a reference to the hard, stony core enclosed within certain fruits. This linguistic root reflects the term's initial association with the durable pits characteristic of drupes, such as those in cherries or peaches. In , "pyrena" first appeared in the early . The earliest documented English usage dates to 1800, in the work of British and physician John Hull, who employed it to denote the stone-like structure in drupaceous . In English, "pyrena" is pronounced /paɪˈriːnə/, emphasizing the long "i" sound. Variations occur in other languages; for instance, the French equivalent "noyau" (meaning "kernel" or "pit") is pronounced /nwa.jo/ and shares a similar conceptual origin in describing fruit stones.

Synonyms and Usage

In botanical terminology, "pyrena" is commonly synonymous with "pyrene," referring to the hard, ossified structure enclosing the seed in drupaceous fruits. Other frequent synonyms include "pit," "stone," and "endocarp stone," where "pit" is often used informally in English-speaking contexts to describe the core of fruits such as peaches. These terms emphasize the pyrena's role as the lignified endocarp layer, distinguishing it from softer fruit components. The term "pyrena" is specifically applied in scientific contexts to denote the ossified endocarp of drupes, whereas "stone" may encompass broader hard fruit cores, including those not strictly drupaceous. This precision aids in drupe classification, underpinning terminological consistency in botanical descriptions. In taxonomic literature on the Rosaceae family, "pyrene" appears frequently to characterize fruit morphology, as seen in studies of genera like Rubus and Crataegus, where it denotes the hardened endocarp influencing species identification. Regional linguistic variations reflect similar concepts, with equivalents such as German "Stein" and Spanish "hueso" used for fruit stones in agricultural and botanical . These terms appear in international standards for variety descriptions, ensuring cross-lingual alignment in analysis.

Botanical Definition and Characteristics

Core Structure

The pyrena, also known as the stone or pit, constitutes the hardened endocarp layer of the pericarp in drupe fruits, forming a protective, lignified shell composed primarily of thick-walled sclereid cells that surround one or more seeds. This structure arises from the sclerification of the inner pericarp tissue, creating a rigid, bony enclosure that safeguards the seed against mechanical damage and desiccation. In typical drupes, the endocarp's sclereids are arranged in one or more layers, often with minimal lumina, providing the pyrena's characteristic stony texture. Internally, the pyrena encloses a single in monopyrenous types, such as those found in olives, where the seed is anchored to the inner endocarp via the funiculus at the hilum. In polypyrenous drupes, the fruit contains multiple pyrenae, each typically enclosing a single , or aggregate drupes like raspberries consist of numerous drupelets, each harboring its own monoseeded pyrena. The internal architecture features a compact cavity lined by the sclerified endocarp, varying in thickness from one to several cell layers of sclereids, with the adhering closely to this lining. Externally, the pyrena displays a smooth, ridged, or grooved surface, often with reticulate or convex sculpturing on the dorsal side and a ventral groove or flat area, varying by to facilitate dispersal or processing. Common pyrenae measure 1–5 cm in length, with the structure attached to the surrounding mesocarp via the region at its base. In drupe fruits, this endocarp layer defines the pyrena as the central stony component. The pyrena, also known as the stone or pit, is the hardened endocarp of a that encloses the , distinguishing it from the seed itself, which is the fertilized containing the and capable of . While the pyrena provides a protective bony layer around the , the seed is the internal reproductive unit that develops into a new upon suitable conditions. In contrast to dry fruits such as achenes or nuts, the pyrena is a component of fleshy drupes characterized by an ossified endocarp surrounding the , whereas achenes are small, indehiscent fruits with a thin pericarp that does not adhere to the single enclosed , as seen in sunflower fruits. Nuts, on the other hand, are dry, indehiscent fruits with a thick, woody pericarp derived from a syncarpous , lacking the fleshy outer layers typical of drupes containing a pyrena, such as in acorns or hazelnuts. This specificity to drupes helps in botanical , avoiding confusion with these dry fruit types that do not feature a succulent mesocarp. Within the overall anatomy of a , the pyrena corresponds solely to the inner endocarp layer of the pericarp, separate from the outer exocarp (which forms the skin) and the middle mesocarp (which is the fleshy portion). This layered structure of the pericarp underscores the pyrena's role as the innermost protective element, distinct from the external fruit tissues that aid in dispersal.

Development and Formation

Biological Processes

The formation of the pyrena begins shortly after fertilization in drupaceous fruits, with the process initiating in the endocarp layer of the developing pericarp. Post-pollination, typically within 30–45 days after bloom, the endocarp undergoes initial differentiation as cells begin to specialize, driven by genetic programs that establish tissue identity. This stage sets the foundation for the pyrena's protective role, progressing over 2–3 weeks as cells prepare for hardening. Cell differentiation in the endocarp follows, where parenchyma cells transform into stone cells through and the activation of secondary wall formation pathways. Transcription factors such as NAC family members (e.g., NST1 and NST3) and genes (e.g., SHP and STK) play crucial roles in regulating this differentiation, upregulating genes involved in to direct cell fate toward lignification. These genetic controls ensure targeted development in the endocarp, creating a structured layer that will form the pyrena's core. Hormonally, auxins like (IAA) establish gradients that pattern tissue development and promote this differentiation phase. The ossification process then ensues, characterized by the thickening of cell walls through secondary growth, which imparts rigidity to the structure by fruit maturity. This involves the deposition of materials in the secondary walls, starting in a slender layer along the fruit's suture and expanding outward, resulting in a hardened endocarp that encases the seed. Auxins continue to modulate cell expansion and wall reinforcement. By the end of maturation, the pyrena achieves its durable form, completing the biological sequence from fertilization to a protective stone.

Chemical and Physical Composition

The pyrena, the hardened endocarp of drupes, derives its rigidity primarily from lignocellulosic components in the sclereid cell walls. forms the dominant structural , comprising up to 45-50% of the dry weight in species such as (Prunus persica) and (), where it cross-links to enhance mechanical resistance and prevent deformation. accounts for approximately 20-30% of the composition, providing tensile strength through its crystalline microfibrils, while , at around 15%, acts as a matrix to bind these elements together, contributing to overall flexibility under stress. Minor further bolsters durability through the incorporation of crystals within endocarp cells, often appearing as prismatic or druse formations that increase localized hardness and support calcium in the tissue. These crystals are documented in various drupaceous endocarps, including those of Bursera species and other Rosaceae fruits, where they embed in the lignified matrix without comprising more than a few percent of the total mass. Physically, the pyrena exhibits exceptional , for example approximately 150 MPa in coconut (Cocos nucifera) endocarp, due to the dense, hierarchical arrangement of lignified cells. This property, combined with lignin's inherent hydrophobicity, renders the structure highly impermeable to and pathogens, minimizing degradation and ensuring long-term seed viability.

Occurrence in Plants

In Rosaceae Family

The family, comprising approximately 2,500 species across more than 90 genera, prominently features pyrenae in its drupaceous fruits, particularly within the Prunoideae subfamily, where these hardened endocarps enclose seeds and contribute to the family's ecological and economic importance. These structures are concentrated in temperate regions of the , reflecting the family's evolutionary adaptations to diverse climates and dispersal strategies. A classic example is the cherry (Prunus avium), which produces a monopyrenous containing a single smooth pyrena that ossifies from the endocarp to protect the during dispersal. In the plum (Prunus domestica), the pyrena exhibits a furrowed surface, enhancing its structural durability while maintaining the monopyrenous form typical of the genus. Similarly, the apricot (Prunus armeniaca) features a pyrena adapted for splitting in certain cultivars, with a thinner, cleavable endocarp that facilitates release and is linked to reduced biosynthesis during development. Within , pyrenae are predominantly monopyrenous, containing a single per , which supports endozoochory as the primary dispersal mechanism; animals ingest the fleshy mesocarp and excrete the intact pyrena, promoting wide distribution in temperate forests. This trait has evolved notably in the genus, where pyrenae variations—such as surface texture and thickness—correlate with habitat-specific adaptations for animal-mediated dispersal and protection.

In Other Plant Families

Beyond the Rosaceae family, pyrenas occur in various angiosperm lineages, particularly in drupaceous fruits where the endocarp ossifies to form a protective structure around the . In the family, the (Olea europaea) produces a with an elongated pyrena, characterized by a hard, woody endocarp that encloses a single and is commonly referred to as the pit. This pyrena is ovoid to globose, measuring 1–2 cm in length, and develops from the lignified inner layer of the fruit wall, providing robust protection in Mediterranean climates. The family exemplifies polypyrenous , as seen in ( spp.), where the fruit is a bilocular containing two pyrenes—each a hardened endocarp surrounding a —that are separated by a central partition and milled during processing. These pyrenes are typically and contribute to the fruit's role in through animal consumption. In the family, species like huckleberries ( spp.) produce containing 2–10 pyrenae, each enclosing a . In the family, () features a fibrous pyrena, a thick, sclerotic endocarp that encases the within the 's fleshy mesocarp, often developing irregular fibers for added structural integrity in tropical environments. This adaptation contrasts with the smoother pyrenas in temperate like those in , highlighting family-specific morphological diversity. Tropical families like and often exhibit thicker, more fibrous or multi-seeded pyrenas suited to high-humidity dispersal, whereas temperate pyrenas are more compact and elongated for arid resilience. Phylogenetically, the ossified endocarp forming pyrenas has evolved independently across multiple angiosperm lineages, including , , and , as a convergent for against herbivory and environmental stress.

Ecological and Human Significance

Role in Seed Protection and Dispersal

The pyrena, consisting of the hardened endocarp enclosing the seed, serves as a primary protective structure against environmental threats during the post-dispersal phase of plant reproduction. Its lignified composition forms a tough, woody barrier that resists mechanical damage from herbivores, preventing the seed from being crushed or consumed outright. This resistance to digestion is particularly evident in endozoochorous dispersal, where animals ingest the surrounding fleshy fruit but excrete the intact pyrena due to its waterproof and durable nature. Additionally, the pyrena's impermeable structure inhibits pathogen entry by blocking microbial invasion and fungal colonization, thereby reducing the risk of seed rot in moist soil conditions. The pyrena also contributes to seed longevity in the soil, allowing viability to persist for several years under varying environmental stresses. This durability arises from the endocarp's high lignin content, which shields the seed from desiccation, temperature fluctuations, and oxidative damage, enabling the formation of temporary soil seed banks that buffer against unfavorable germination conditions. In ecosystems with irregular disturbance, such as fire-prone habitats, this extended persistence ensures that pyrenae remain viable until suitable cues trigger germination. In terms of dispersal, the pyrena facilitates endozoochory as the primary mechanism, where mammals and birds consume the attractive fleshy pericarp of drupes and deposit the indigestible pyrenae away from the parent plant via feces. For instance, in species like cherries (), birds such as thrushes ingest the fruit and excrete pyrenae intact, promoting wide-ranging dispersal over kilometers. Similarly, larger mammals, including bears, aid in dispersing pyrenae of drupes like those in blackberries () through gut passage, with the hard structure ensuring seed survival during transit. These strategies enhance by relocating seeds to new microsites with reduced competition and predation risk. Evolutionarily, the pyrena confers advantages by improving post-dispersal rates through natural during gut passage or environmental exposure. The abrasive action in animal digestive tracts or abrasion weakens the endocarp without harming the coat, breaking physical and accelerating water uptake for emergence. This , seen in drupes like peaches, has driven the diversification of endocarp traits in response to pressures, optimizing in animal-mediated ecosystems.

Culinary Uses and Hazards

In culinary preparations involving drupes such as cherries (Prunus avium) and plums (Prunus domestica), the pyrena—the hardened endocarp enclosing the seed—is routinely removed prior to processing to ensure edibility and safety, particularly when making jams, preserves, and syrups where the flesh is the primary component. This pitting step prevents accidental ingestion of the indigestible structure and mitigates potential toxin release during cooking. In contrast, the kernels within certain pyrenae, like those of cherries, have been traditionally extracted and used sparingly to impart an almond-like flavor to liqueurs and extracts, as seen in recipes for cherry pit-infused spirits where the pits are roasted and steeped in alcohol. However, such uses are limited due to inherent risks, and extraction of oils from pyrenae kernels, as in apricot (Prunus armeniaca) varieties, occurs in controlled industrial settings for flavoring agents, though the toxic nature of the kernels restricts widespread application. A primary associated with pyrenae in the genus stems from their content of cyanogenic s, such as , which hydrolyze upon crushing or digestion to release (HCN), a potent capable of causing . In species like apricots and bitter almonds (Prunus dulcis var. amara), consumption of more than three small raw kernels can exceed safe levels, leading to symptoms including , , and in severe cases, or death, with a reported fatal dose of 0.56–1.52 mg/kg body weight. Documented pediatric cases of from highlight the risks, particularly when marketed as health supplements, prompting regulatory warnings from agencies like the FDA against raw kernel consumption. Cooking or processing can reduce glycoside levels, but raw or minimally processed pyrenae kernels remain hazardous, especially in children. The durability of pyrenae, owing to their lignified composition, facilitates their preservation in archaeological contexts, providing valuable evidence of ancient fruit consumption and trade; for instance, carbonized Prunus endocarps from Neolithic sites in the Yangtze River Valley (ca. 8000–7000 BP) and Mediterranean regions (ca. 5850–4500 cal BC) indicate early domestication and use of peaches, plums, and related species. These remains, often recovered from stratified layers and pits, offer insights into prehistoric diets without perishable flesh degradation. In , pyrenae play a role in breeding programs for species, where selection for robust endocarp traits contributes to developing hardier varieties resistant to mechanical damage, pathogens, and environmental stresses, enhancing overall crop resilience and economic viability in stone fruit production. Such efforts, including interspecific hybridization, support global cultivation of economically significant fruits like peaches and cherries, with improvements yielding higher yields and reduced losses.

References

  1. http://www.mobot.org/mobot/latindict/keyDetail.aspx?keyWord=drupe
  2. https://www.dictionary.com/browse/pyrene
  3. https://www.yourdictionary.com/pyrena
  4. https://www.merriam-webster.com/dictionary/pyrena
  5. https://crosbyholmegrown.uk/resources/description-classification-botany/botany/botany-seven-fruit/
  6. https://oldfern.co.uk/wood/Trees/glossary-botany.php
  7. https://www.tandfonline.com/doi/full/10.1080/23818107.2019.1663448
  8. https://www.oed.com/dictionary/pyrene_n1
  9. https://www.mobot.org/mobot/latindict/keyDetail.aspx?keyWord=drupe
  10. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/endocarp
  11. http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=10776
  12. https://www.sciencedirect.com/science/article/abs/pii/S036725300900139X
  13. https://www.journalssystem.com/agb/Morphological-Features-of-Fruits-and-Seeds-of-Some-Species-of-the-Genus-Crataegus%2C159848%2C0%2C2.html
  14. https://www.upov.int/documents/d/upov/tg-documents-en-tg230_01_corr.pdf
  15. https://www.upov.org/fr/publications/tg-rom/tg070/tg_70_4_rev.pdf
  16. https://scholarworks.uark.edu/cgi/viewcontent.cgi?article=1036&context=inquiry
  17. https://bsapubs.onlinelibrary.wiley.com/doi/10.3732/ajb.1500204
  18. https://www.researchgate.net/publication/297406211_Pyrene_Attributes_and_Seediness_Evaluation_of_Blackberry_Genotypes
  19. https://idtools.org/seed_families/index.cfm?pageID=1582
  20. https://blogs.ubc.ca/biol343/fruit-types/
  21. https://mgnv.org/plants/glossary/fruit-pericarp-endocarp-exocarp-mesocarp/
  22. https://pmc.ncbi.nlm.nih.gov/articles/PMC9690734/
  23. https://pmc.ncbi.nlm.nih.gov/articles/PMC4070412/
  24. https://doi.org/10.1186/1741-7007-8-13
  25. https://doi.org/10.1111/j.1365-313X.2008.03633.x
  26. https://doi.org/10.1038/nature07875
  27. https://doi.org/10.3389/fpls.2014.00284
  28. https://biotechnologyforbiofuels.biomedcentral.com/articles/10.1186/s13068-018-1305-7
  29. https://www.researchgate.net/publication/7876352_Calcium_oxalate_in_plants_Formation_and_function
  30. https://pmc.ncbi.nlm.nih.gov/articles/PMC3484315/
  31. https://www.sciencedirect.com/science/article/pii/S0264127520304780
  32. https://www.britannica.com/plant/Rosaceae
  33. https://www.digitalatlasofancientlife.org/learn/embryophytes/angiosperms/fruits/
  34. https://www.sciencedirect.com/science/article/abs/pii/S0168169916308523
  35. https://bmcplantbiol.biomedcentral.com/articles/10.1186/s12870-017-1023-5
  36. https://academic.oup.com/aob/article/100/7/1585/216663
  37. https://www.fs.usda.gov/nsl/Wpsm/Olea.pdf
  38. https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:747038-1/general-information
  39. https://www.researchgate.net/publication/369323252_Mango_seed_kernel_Nutrient_composition_and_quality_characteristics_of_Oil
  40. https://www.researchgate.net/publication/263861680_Evolution_of_the_fruit_endocarp_molecular_mechanisms_underlying_adaptations_in_seed_protection_and_dispersal_strategies
  41. https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2019.00265/full
  42. https://www.kopiaste.org/2014/07/easy-cherry-pit-liqueur/
  43. https://foragerchef.com/eating-the-whole-cherry/
  44. https://www.simplyrecipes.com/stone-fruit-pit-liqueur-recipe-5223069
  45. https://ageconsearch.umn.edu/record/337126/files/DeptBulletin350.pdf
  46. https://www.efsa.europa.eu/en/press/news/160427
  47. https://pmc.ncbi.nlm.nih.gov/articles/PMC7009189/
  48. https://www.canada.ca/en/health-canada/services/food-nutrition/reports-publications/food-safety/cyanide-bitter-apricot-kernels.html
  49. https://caybdergi.com/articles/pediatric-cyanide-poisoning-after-ingestion-of-apricot-seeds/cayd.galenos.2019.06977
  50. https://www.fda.gov/food/alerts-advisories-safety-information/fda-issues-warning-about-toxic-amygdalin-found-apricot-seeds
  51. https://www.aliem.com/acmt-toxicology-visual-pearl-apricot-kernels/
  52. https://www.cfs.gov.hk/english/whatsnew/whatsnew_fst/whatsnew_fst_Natural_Toxins_in_Bitter_Apricot_Seeds.html
  53. https://pmc.ncbi.nlm.nih.gov/articles/PMC4156326/
  54. https://pmc.ncbi.nlm.nih.gov/articles/PMC7117749/
  55. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0106595
  56. https://www.mdpi.com/2073-4395/13/4/1027
  57. https://www.researchgate.net/publication/287729219_Breeding_and_selection_of_prunus_rootstocks_at_the_aula_dei_experimental_station_Zaragoza_Spain
  58. https://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392015000300002
  59. https://www.mdpi.com/2311-7524/10/12/1381
Add your contribution
Related Hubs
Contribute something
User Avatar
No comments yet.