What is the primary classification of Gunnerales within the plant kingdom?

Gunnerales is classified as an order of flowering plants. This means it represents a group of plants that produce flowers and fruits, and it is a significant taxonomic rank above family and below class.

According to the APG III and APG IV classification systems, which genera are included in the order Gunnerales?

The APG III (2009) and APG IV (2016) systems place two genera within the Gunnerales order: *Gunnera*, belonging to the family Gunneraceae, and *Myrothamnus*, belonging to the family Myrothamnaceae.

How did older classification systems, such as the Cronquist and Takhtajan systems, categorize the families now placed in Gunnerales?

In older systems like the Cronquist (1981) and Takhtajan (1997), the Gunneraceae family was placed within the order Haloragales, while the Myrothamnaceae family was placed in the order Hamamelidales. This differs from modern classifications that group them together.

What evidence led to the grouping of Gunneraceae and Myrothamnaceae into the order Gunnerales, despite their morphological differences?

DNA analysis provided definitive evidence for grouping the Gunneraceae and Myrothamnaceae into the order Gunnerales. This grouping was considered a surprise because the two families exhibit very dissimilar physical characteristics, or morphologies, making their genetic relatedness unexpected.

Where does the order Gunnerales fit within the broader classification of flowering plants in modern systems like APG III and APG IV?

In modern classification systems, such as APG III and APG IV, the order Gunnerales is noted as being the first group to diverge from the core eudicots, indicating its early position in the evolutionary history of flowering plants.

What is the geological time period associated with the earliest known fossils of Gunnerales?

The earliest fossils attributed to the Gunnerales order date back to the Aptian stage, which occurred approximately 125 to 0 million years ago (Ma). This period is part of the Early Cretaceous epoch.

In which geographical locations have early fossil pollen samples, identified as Tricolpites, been found, and what was the continental context at that time?

Early fossil pollen samples, known as Tricolpites, have been discovered in Antarctica, Egypt, and Argentina. During the Aptian stage when these fossils originated, these landmasses were part of the supercontinent known as Gondwana.

What is a shared chemical characteristic found in both the Gunneraceae and Myrothamnaceae families?

Both the Gunneraceae and Myrothamnaceae families contain ellagic acid, a type of phenolic compound. This is one of the shared biochemical traits noted for the order.

Describe the characteristic features of the phloem cells and leaf borders within the Gunnerales order.

Within the Gunnerales order, the phloem cells are notable for containing a large number of plastids, which are organelles involved in photosynthesis and other metabolic processes. Additionally, the leaves of these plants typically have dented or toothed borders.

What are the reproductive characteristics of plants within the Gunnerales order?

Plants belonging to the Gunnerales order are dioecious, meaning individual plants are either male or female, producing either male or female reproductive organs. They also possess small flowers that lack a perianth, which is the collective term for the sepals and petals of a flower.

What is the nature of the stigma in Gunnerales flowers?

The stigma, the receptive tip of a carpel, in Gunnerales flowers is described as being secretory, at least weakly. This means it produces substances that can aid in pollen germination.

What are some key genetic and metabolic characteristics shared by Gunnerales and the core eudicots?

Gunnerales shares several genetic and metabolic traits with core eudicots. These include the ability to produce cyanogenesis from phenylalanine, specific metabolic pathways for isoleucine or valine, the presence of a PI-dB motif DNA sequence, and a common small deletion in the 18S ribosomal DNA sequence.

Which specific genetic traits do Gunnerales share with Buxales and Trochodendrales, in addition to core eudicots?

Gunnerales shares three specific genetic traits with Buxales and Trochodendrales: the absence of benzylisoquinoline alkaloids, the presence of euAP3 + TM6 genes (which represent a Class B gene duplication), and the loss of the mitochondrial gene rps2.

How do the ecological adaptations and appearances of Gunneraceae and Myrothamnaceae differ?

The Gunneraceae are typically mesophilic herbs, often large, with well-developed hydathodes that secrete mucilage or a resinous coating. In contrast, the Myrothamnaceae are reviviscent shrubs adapted to arid environments, featuring poorly developed hydathodes that secrete plant resin.

What is a key difference in the flowers of Gunneraceae and Myrothamnaceae, despite both lacking a perianth?

While both Gunneraceae and Myrothamnaceae have flowers that lack a perianth (sepals and petals), the specific details of their pollen grains differ significantly, as noted in various botanical studies.

What is the significance of the APG IV system in classifying flowering plants?

The APG IV system is a widely recognized framework for classifying flowering plants, and it places the Gunnerales order as one of the earliest diverging lineages from the core eudicots. This system is based on genetic and molecular data.

What does the term reviviscent shrub imply about the Myrothamnaceae family?

The term reviviscent shrub suggests that plants in the Myrothamnaceae family have the ability to revive or rehydrate after periods of extreme dryness, a common adaptation for survival in arid habitats.

What is the function of hydathodes in plants like those in the Gunneraceae family?

Hydathodes are structures on plant leaves that can secrete fluids, such as mucilage or a resinous coating in the case of Gunneraceae. This secretion can play roles in protection, water balance, or deterring herbivores.

What is the significance of Tricolpites in the context of Gunnerales paleontology?

Tricolpites refers to early pollen samples discovered from the Aptian stage that are associated with the Gunnerales order. Their discovery in locations like Antarctica, Egypt, and Argentina provides insights into the ancient distribution of these plants.

How does the classification of Gunneraceae and Myrothamnaceae in the Cronquist system differ from modern APG systems?

In the Cronquist system, Gunneraceae was placed in Haloragales and Myrothamnaceae in Hamamelidales, whereas modern APG systems group them together in Gunnerales, reflecting a significant shift in understanding their evolutionary relationships based on molecular data.

What does it mean for an order to be the first to diverge from the core eudicots?

This statement means that Gunnerales represents one of the earliest evolutionary branches among the group of flowering plants known as eudicots. It helps scientists understand the initial diversification of this major plant group.

What is the temporal range of the Gunnerales order, as indicated by fossil evidence?

The temporal range of the Gunnerales order is from the Aptian stage (approximately 125 to 0 million years ago) to the present day, indicating its ancient origins and continued existence.

What is the role of DNA analysis in the classification of Gunnerales?

DNA analysis proved definitive in establishing the order Gunnerales, grouping the families Gunneraceae and Myrothamnaceae together. This molecular evidence was crucial in overcoming the apparent morphological differences between them.

What is the common name or description for the order Gunnerales?

Gunnerales is described as an order of flowering plants.

What is the significance of the euAP3 + TM6 genes in the context of Gunnerales' evolutionary relationships?

The presence of euAP3 + TM6 genes, which represent a Class B gene duplication, is a shared characteristic between Gunnerales, Buxales, and Trochodendrales, contributing to the understanding of their phylogenetic connections.

What does the term dioecious mean in relation to the plants in the Gunnerales order?

Dioecious means that individual plants within the Gunnerales order are either male or female, possessing separate male and female reproductive organs on different plants.

What is the significance of the loss of the mitochondrial gene rps2 in Gunnerales?

The loss of the mitochondrial gene rps2 is another genetic characteristic that Gunnerales shares with Buxales and Trochodendrales, further highlighting evolutionary links between these plant groups.

What is the general appearance of plants in the Gunneraceae family?

Plants in the Gunneraceae family are typically mesophilic herbs, often characterized by their oversized growth.

What is the general appearance of plants in the Myrothamnaceae family?

Plants in the Myrothamnaceae family are described as reviviscent shrubs, meaning they can survive periods of desiccation and revive when conditions improve, typically found in arid habitats.

What does the term mesophilic imply about the habitat of Gunneraceae?

Mesophilic suggests that plants in the Gunneraceae family thrive in moderate environmental conditions, typically referring to moderate temperature and moisture levels, as opposed to extreme heat or dryness.

What is the significance of the dented borders on the leaves of Gunnerales plants?

Dented borders on the leaves are a morphological characteristic observed in plants of the Gunnerales order, contributing to their overall physical description.

What is the role of the PI-dB motif in the genetic makeup of Gunnerales and core eudicots?

The presence of the PI-dB motif in their DNA sequence is a shared characteristic between Gunnerales and core eudicots, indicating a common genetic feature inherited from a shared ancestor.

What is the significance of the Tricolpites pollen found in Aptian-aged fossils?

The discovery of Tricolpites pollen in Aptian-aged fossils from locations like Antarctica, Egypt, and Argentina is significant because it provides evidence for the early presence and distribution of plants belonging to the Gunnerales order.

What does the term APG stand for in the context of plant classification?

APG stands for Angiosperm Phylogeny Group, which is an informal international consortium of researchers who work on the classification of flowering plants based on molecular data.

What is the significance of the Gunneraceae family in the classification of Gunnerales?

Gunneraceae is one of the two families that constitute the order Gunnerales, containing the genus Gunnera. It was previously placed in the order Haloragales in older classification systems.

What is the significance of the Myrothamnaceae family in the classification of Gunnerales?

Myrothamnaceae is the other family within the order Gunnerales, containing the genus Myrothamnus. It was formerly classified under the order Hamamelidales.

What does the term core eudicots refer to in plant classification?

Core eudicots represent a major clade within the eudicots, encompassing the majority of flowering plant species. Gunnerales is considered to have diverged before this core group fully established.

What is the significance of the Cronquist system in botanical classification?

The Cronquist system, published in 1981, was a widely influential system for classifying flowering plants. Its placement of Gunneraceae and Myrothamnaceae in different orders highlights how molecular data has led to revisions in taxonomy.

What is the significance of the Takhtajan system in botanical classification?

The Takhtajan system is another system of plant classification, proposed by Armen Takhtajan. Like the Cronquist system, it placed Gunneraceae and Myrothamnaceae in different orders before modern molecular studies led to their current grouping in Gunnerales.

What does the term phylogeny refer to in the context of plant classification?

Phylogeny refers to the evolutionary history and relationships among individuals or groups of organisms. The classification of Gunnerales is based on phylogenetic studies, particularly DNA analysis.

What is the purpose of including external links in a Wikipedia article like this one?

External links, such as the reference to the Angiosperm Phylogeny Website, provide readers with additional resources for further research and verification of the information presented in the article.

What is the significance of the Aptian stage in the context of Gunnerales fossils?

The Aptian stage is significant because it represents the geological period from which the earliest known fossils associated with the Gunnerales order have been dated, providing evidence for their ancient origins.

What does the term morphology mean in biology?

Morphology refers to the study of the form and structure of organisms and their specific structural features. The article notes that the morphological differences between Gunneraceae and Myrothamnaceae were surprising given their genetic relatedness.

What is the role of Gunnera and Myrothamnus as genera within the order Gunnerales?

Gunnera and Myrothamnus are the only two genera recognized within the order Gunnerales by the APG III and APG IV classification systems. They represent the entirety of this taxonomic order.

What does the term basal angiosperms refer to in plant classification?

Basal angiosperms are groups of flowering plants that are considered to have diverged early in the evolutionary history of angiosperms. The article notes that Gunnerales is considered basal among the eudicots.

What is the significance of the APNI identifier for Gunnerales?

APNI, or the Australian Plant Name Index, is a database that provides a unique identifier for the taxonomic name Gunnerales, facilitating its cataloging and retrieval in botanical resources.

What does the GBIF identifier for Gunnerales signify?

The GBIF (Global Biodiversity Information Facility) identifier links Gunnerales to a vast international network of biodiversity data, allowing access to occurrence records and other information about the distribution of species within this order.

What is the purpose of the Wikidata identifier for Gunnerales?

The Wikidata identifier connects the Gunnerales entry to a structured knowledge base, allowing for cross-linking with other related entities and data across different Wikipedia articles and projects.

What is the significance of the iNaturalist identifier for Gunnerales?

The iNaturalist identifier links Gunnerales to a platform for citizen science and biodiversity observation, potentially showing user-submitted sightings and data related to species within this order.

What is the meaning of the term reviviscent in the context of Myrothamnaceae?

Reviviscent means having the ability to revive or come back to life after a period of dormancy or apparent death, often due to extreme environmental conditions like drought. This characteristic is noted for the Myrothamnaceae shrubs.

What is the significance of the EPPO code for Gunnerales?

The EPPO (European and Mediterranean Plant Protection Organization) code is used for plant quarantine and trade purposes. Having an EPPO code for Gunnerales indicates its relevance in agricultural or horticultural contexts, potentially related to pest or disease management.

Gunnerales Wiki: The Gunnerales: An Evolutionary Journey in Botany

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The Order Gunnerales

Defining the Order

The Gunnerales constitute a significant order within the angiosperms, comprising two genera: Gunnera (family Gunneraceae) and Myrothamnus (family Myrothamnaceae). This classification, established by the Angiosperm Phylogeny Group (APG) systems (APG III and APG IV), reflects a surprising phylogenetic relationship based on molecular data, despite considerable morphological differences between the constituent families.^[2]^[3]

Ancient Lineages

Fossil evidence indicates the presence of lineages related to the Gunnerales dating back to the Aptian stage of the Cretaceous period. Pollen samples attributed to this order have been discovered in geological formations in Antarctica, Egypt, and Argentina, suggesting an ancient distribution across the supercontinent Gondwana.^[4]^[5]^[6]

Historical Classification

In earlier taxonomic systems, such as the Cronquist system (1981), the Gunneraceae were placed within the order Haloragales, while the Myrothamnaceae were assigned to the Hamamelidales. The modern APG classifications, however, unite these morphologically disparate families based on robust genetic evidence, highlighting the power of molecular phylogenetics in resolving evolutionary relationships.^[2]

Constituent Families

Gunneraceae

This family is primarily represented by the genus Gunnera. Species within this genus are often characterized as large, mesophilic herbs, frequently featuring substantial foliage. They possess well-developed hydathodes, which are structures capable of secreting mucilage or a resinous coating, playing a role in guttation or defense.^[1]

Myrothamnaceae

In contrast, the Myrothamnaceae family contains the genus Myrothamnus. These plants are adapted to arid habitats and are known for their remarkable reviviscent properties, allowing them to survive extreme dehydration. Their hydathodes are typically less developed compared to Gunneraceae, and they secrete plant resin.^[1]

Shared Biochemical Traits

Despite their ecological and morphological differences, both families share certain biochemical and morphological characteristics. Notably, they both produce ellagic acid. Additionally, their leaves exhibit dented borders, and their phloem cells contain a significant number of plastids.^[1]

Morphological and Reproductive Features

Floral and Vegetative Characteristics

The Gunnerales order is characterized by several distinct features. Botanically, the plants are typically dioecious, meaning individuals are either male or female. Their flowers are small and lack petals (apetalous). A notable feature is the stigma, which is at least weakly secretory, suggesting a specialized mechanism for pollen capture and germination.^[1]

Key shared characteristics include:

Presence of ellagic acid.
Phloem cells containing numerous plastids.
Leaves with dented (serrated) borders.
Dioecious reproductive systems.
Small flowers lacking perianths.
A secretory stigma.

These traits, combined with genetic data, help define the order's unique position in plant evolution.

Genetic Markers

The placement of Gunnerales within the core eudicots is supported by specific genetic markers. These include the capacity for cyanogenesis via phenylalanine pathways, metabolic pathways related to isoleucine or valine, the presence of the PI-dB motif in DNA, and a common characteristic of a small deletion in the 18S ribosomal DNA sequence.^[2]

Ecological Adaptations

Mesic vs. Arid Habitats

The ecological strategies of the Gunnerales families present a notable contrast. The Gunneraceae, exemplified by Gunnera species, are typically found in mesophilic (moisture-loving) environments and often grow as large herbs. Their well-developed hydathodes suggest adaptations for managing water balance in consistently moist conditions.^[1]

Resilience and Survival

Conversely, the Myrothamnaceae, represented by Myrothamnus, are adapted to arid conditions. These shrubs exhibit remarkable resilience, capable of surviving severe dehydration. Their poorly developed hydathodes and the secretion of plant resin are likely adaptations to conserve water and protect against environmental stress in dry habitats.^[1]

Taxonomic Classification

Hierarchical Placement

The taxonomic hierarchy places Gunnerales within the broader framework of flowering plants. As per the APG IV system, they are situated within the core eudicots, representing an early diverging lineage.

Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Core eudicots
Order:	Gunnerales Takht. ex Reveal
Families
Gunneraceae Myrothamnaceae

Evolutionary Significance

Basal Position

The Gunnerales hold a significant position in plant evolutionary history as one of the earliest diverging orders within the core eudicots. This basal placement indicates that they branched off relatively early in the evolutionary trajectory of this major angiosperm clade.^[2]^[3]

Bridging Divergent Traits

The order serves as a fascinating example of evolutionary divergence, uniting families with markedly different morphologies and ecological adaptations. The genetic data, which proved crucial in establishing this relationship, reveals shared ancestral traits alongside unique derived characteristics, providing insights into the early diversification of angiosperms.^[2]

Ancient Origins and Distribution

The fossil record, particularly from Aptian-aged deposits in Antarctica, Egypt, and Argentina, points to the ancient origins of the Gunnerales. Their presence on these landmasses, which were once part of the Gondwana supercontinent, underscores their deep evolutionary history and past geographical distribution.^[4]^[5]^[6]

Taxonomic Identifiers

Standardized References

To ensure precise identification and facilitate cross-referencing within biological databases, the Gunnerales order is associated with various standardized identifiers:

Wikidata: Q21846
Wikispecies: Gunnerales
APNI: 214978
CoL: 8ZXX9
EoL: 10554606
EPPO: 1GUNO
GBIF: 7219294
iNaturalist: 71283
IRMNG: 12578
ITIS: 846623
NBN: NHMSYS0020824591
NCBI: 232382
NZOR: 13d3d4d8-017f-4a5f-945a-ff02a9fd1cc6
Open Tree of Life: 134738
Paleobiology Database: 182994
Tropicos: 50324562
VASCAN: 32944
WFO: wfo-9000000238
WoRMS: 886427

References

Source Citations

The information presented on this page is derived from the following sources:

Ibrahim, I.A Mohamed (1996). "Aptian-Turonian palynology of the Ghazalat-1 Well (GTX-1), Qattara Depression, Egypt". Review of Palaeobotany and Palynology. 94 (1–2): 137–168. doi:10.1016/0034-6667(95)00135-2.
Angiosperm Phylogeny Group (2009). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III". Botanical Journal of the Linnean Society. 161 (2): 105–121. doi:10.1111/j.1095-8339.2009.00996.x. hdl:10654/18083.
Angiosperm Phylogeny Group (2016). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV". Botanical Journal of the Linnean Society. 181 (1): 1–20. doi:10.1111/boj.12385. ISSN 0024-4074.
Leppe, Marcelo; Mihoc, Maritza; Varela, Natalia; Stinnesbeck, Wolfgang; Mansilla, Héctor; Bierma, Hessel; Cisterna, Katherine; Frey, Eberhard; Jujihara, Toshiro (December 2012). "Evolution of the Austral-Antarctic flora during the Cretaceous: New insights from a paleobiogeographic perspective". Revista chilena de historia natural. 85 (4): 369–392. doi:10.4067/S0716-078X2012000400002. hdl:10533/140416. ISSN 0716-078X.
Perez Loinaze, Valeria S.; Archangelsky, Sergio; Cladera, Gerardo (April 2012). "Palynostratigraphic study of the Early Cretaceous Río Mayer and Kachaike formations at the Quebrada El Moro Section, Austral Basin, southwestern Argentina". Cretaceous Research. 34: 161–171. doi:10.1016/j.cretres.2011.10.015. hdl:11336/98083.
Perez Loinaze, Valeria S.; Vera, Ezequiel I.; Moyano-Paz, Damian; Coronel, Marina D.; Manabe, Makoto; Tsuihiji, Takanobu; Novas, Fernando E. (2023-07-01). "Maastrichtian palynological assemblages from the Chorrillo Formation, Patagonia, Argentina". Review of Palaeobotany and Palynology. 314: 104893. doi:10.1016/j.revpalbo.2023.104893. ISSN 0034-6667.

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References

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The Gunnerales

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The Order Gunnerales ℹ️

🌿 Defining the Order

⏳ Ancient Lineages

📜 Historical Classification

Constituent Families 🌳

🌱 Gunneraceae

🌵 Myrothamnaceae

🧬 Shared Biochemical Traits

Morphological and Reproductive Features 🌸

⚙️ Floral and Vegetative Characteristics

🔬 Genetic Markers

Ecological Adaptations 🌍

💧 Mesic vs. Arid Habitats

☀️ Resilience and Survival

Taxonomic Classification 📊

🏛️ Hierarchical Placement

Evolutionary Significance ⏳

🌱 Basal Position

🔗 Bridging Divergent Traits

🌍 Ancient Origins and Distribution

Taxonomic Identifiers 🔗

🆔 Standardized References

References 📚

📖 Source Citations

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Disclaimer ⚠️

📜 Important Notice

Dive in with Flashcard Learning!

The Order Gunnerales

Defining the Order

Ancient Lineages

Historical Classification

Constituent Families

Gunneraceae

Myrothamnaceae

Shared Biochemical Traits

Morphological and Reproductive Features

Floral and Vegetative Characteristics

Genetic Markers

Ecological Adaptations

Mesic vs. Arid Habitats

Resilience and Survival

Taxonomic Classification

Hierarchical Placement

Evolutionary Significance

Basal Position

Bridging Divergent Traits

Ancient Origins and Distribution

Taxonomic Identifiers

Standardized References

References

Source Citations

Teacher's Corner

True or False?

Test Your Knowledge!

Gamer's Corner

Discover other topics to study!

References

Feedback & Support

Disclaimer

Important Notice