Amantiferae/ Amentifereae: Salient features, families & floral diversity and updated phylogeny

Amentiferae Order or taxon ?
अमेंटिफेरी क्यों खास है ? Phylogeny and characteristics.

Dr. Praveen Mohil
Assistant Professor
Department of Botany, university of Rajasthan

1. Amantiferae / Amentifereae : salient features, floral, families, diversity and phylogeny Subheadings - Salient features of Amantiferae / Amentifereae Floral diversity in Amantiferae / Amentifereae Diversity of families in Amantiferae / Amentifereae Phylogeny of order Amantiferae / Amentifereae

2. Amantiferae / Amentifereae : salient features, floral, families, diversity and phylogeny Dr . Praveen Mohil Assistant Professor Department of Botany University of Rajasthan Jaipur-302004

3. Why this Taxon is so special ? Ans - Understanding the amentiferous nature of these plants helps in recognizing and identifying them based on their inflorescence type . Catkin=Ament--- Racemose (indefinite) + main axis elongated( racemose with long peduncle)---Pendulous spike( Fls sessile) which bear naked pistillate or staminate flowers but not both. Eg . Mulberry ( शहतूत ) Note- order vs Taxon It’s a taxon not order why ?

4. Introduction " Amentiferae " is an old, informal grouping of plants that are characterized by their catkin (ament) inflorescences. A catkin is a dense, elongated cluster of flowers, usually wind-pollinated, and often hanging or drooping. The term " Amentiferae " is not used in modern botanical taxonomy because it does not reflect evolutionary relationships . Modern classifications use genetic and morphological data to place these plants into their respective families within the angiosperms (flowering plants ). Despite this, understanding the amentiferous nature of these plants helps in recognizing and identifying them based on their inflorescence type.

5. (i) Salient features of Amantiferae / Amentifereae General characters- The group Amentiferae (Catkin possess scaly bract, usually flexuous spike or spike like inflorescence) are characterized by trees or shrubs, flower small, unisexual, at least the staminate in elongated catkins, Anemophilly and exalbuminous seeds. Distribution occurs mainly in the North temperate Zone. Catkin (Ament) is a scaly bracteated , usually flexuous spike or spike like inflorescence of cymules .

6. (i) Salient features of Amantiferae / Amentifereae Characteristics of Amentiferae - The primary characteristic of Amentiferae is the presence of catkins (aments). Catkins are typically unisexual, either male or female. Most Amentiferae are wind-pollinated ( anemophilous ). The flowers in catkins are usually small and lack petals, as they do not need to attract insect pollinators. Flowers in catkins often have reduced or absent perianths (petals and sepals), and the reproductive structures are typically exposed for wind dispersal of pollen .

7. (ii) Floral diversity in Amantiferae / Amentifereae Amentifereae exhibits significant floral diversity primarily through variations in inflorescence type, flower structure, and reproductive strategies. This diversity is closely tied to their adaptation to wind pollination and their ecological roles within various habitats. Amentifereae , which includes a group of plants predominantly in the family Fagaceae and occasionally in other families like Betulaceae , displays significant floral diversity. This diversity can be observed in several key aspects of their floral morphology and reproductive strategies.

8. (ii) Floral diversity @Floral Morphology &Flower Structure: Floral Morphology Inflorescence Type: The hallmark of Amentifereae is the presence of catkins ( amenta ), which are elongated, pendent, or erect inflorescences. These catkins can be unisexual or bisexual. Male Catkins: Typically, these are more elongated and bear numerous small, inconspicuous flowers. Female Catkins : Often shorter, these can contain fewer flowers compared to their male counterparts. Bisexual Catkins: Rare but present in some species, where both male and female flowers are found in the same catkin. Flower Structure: Male Flowers: Usually reduced, consisting of stamens and rudimentary perianth parts. The number of stamens can vary significantly. Female Flowers : These typically have a more complex structure with a well-developed ovary, style, and stigma, often accompanied by bracts or scales. Perianth : Generally reduced or absent in male flowers, but can be more developed in female flowers.

9. (ii) Floral diversity @Reproductive Strategies & Sexual Systems: Reproductive Strategies Wind Pollination : Most members are wind-pollinated ( anemophilous ). This is reflected in their floral structures, which are often small, lack bright colors or scents, and produce copious amounts of pollen. Pollen: Light and produced in large quantities to increase the chances of successful pollination. Sexual Systems: Monoecious : Many species are monoecious , meaning that individual plants have both male and female flowers (e.g., oak trees). Dioecious : Some species are dioecious , with individual plants bearing only male or only female flowers (e.g., certain willows).

10. (iii) Diversity of families in Amantiferae / Amentifereae Eichler (1883) classified the order Amentiferae , incuding the following families like Salicaceae , Garryaceae , Myricaceae , Balanopsidaceae , Leitneriaceae , Juglandaceae , Batidaceae , Betulaceae and Fagaceae . They were accepted as a phyletically homogenous group of primitive dicotyledons by Engler and by Rendle both of whom rejected Eichler's name and considered them to represent several orders.

11. (iii) Diversity of families in Amantiferae / Amentifereae In Bentham and Hooker's system, " Amentiferae " are found within the class Dicotyledons (or Dicotyledonae ), under the Cohort (nowadays referred to as order) Amentiferae . This cohort includes several families that were known to have catkin inflorescences. Major Families within Amentiferae are Fagaceae ( Fagus ), Betulaceae ( Betula ), Juglandaceae ( Juglans ), Salicaceae (Salix), Casuarinaceae ( Casuarina ).

12. (iii) Diversity of families in Amantiferae / Amentifereae Hutchinson transferred all these Amentiferous orders ( plus Urticales ) to a phyletic position that treats them as descendents of Hamamelidaceous ancestors. Cronquist and Takhtajan kept these families in their subclass Hamamelidae except Salicaceae and Garryaceae which were kept in Dilleniidae and Rosidae respectively. A wide range of evidence has, presented in support of the view that these dicotyledons are neither natural nor primitive taxa. Engler considered it as the primitive most group of Dicotyledons .

13. (iii) Diversity of families in Amantiferae / Amentifereae In the year 1957, Benson divided group Amentiferae into 10 orders and12 families. These are (1) Salicales : Salicaceae , (2 ) Leitneriales:Leitneriaceae , ( 3) Batidales:Batidaceae , (4) Balanopsidales : Balanopsidaceae , (5) Myricales : Myricaceae , (6) Fagales : Betulaceae , Fagaceae , (7) Garryales : Garryaceae , (8) Julianales:Julianaceae , (9) Juglandales : Rhoipteleaceae , Juglandaceae , (10) Casuarinales : Casuarinaceae .

14. (iii) Diversity of families in Amantiferae / Amentifereae Modern classification systems- recognize several families that include species with catkin-like inflorescences, and these families are distributed across different orders.Here are some of the prominent families historically associated with the Amentiferae due to their catkin-bearing species:1 . Fagaceae , 2. Betulaceae , 3. Salicaceae,4. Juglandaceae,5. Myricaceae & 6. Casuarinaceae Modern Understanding In contemporary taxonomy, the families listed above are classified within different orders such as Fagales ( Fagaceae , Betulaceae , Juglandaceae , and Myricaceae ) and Malpighiales ( Salicaceae ). The grouping of these families based on the presence of catkins is now understood to be more of a morphological similarity rather than an indication of close evolutionary relationships.

15. (iv) Phylogeny of order amentiferae The taxon Amentiferae was established by Linnaeus . In his work, Linnaeus created the taxon Amentiferae to group plants that produce their flowers in catkins ( amenta ), which is a type of inflorescence. Rendle (1865-1938), an English botanist associated with the British Museum of Natural History, published Classification of Flowering Plants (1904, 1925), resembling that of Engler in considering monocots more primitive than dicots and Amentiferae a primitive group under dicots .

16. (iv) Phylogeny of Amantiferae / Amentifereae According to one hypothesis , the amentiferous plants are the most primitive. This is because of the simplicity of their flowers, their lack of coloured petals, and their wind pollination. The stamens are also considered to be quite similar to the microsporophylls of gymnosperms. However, some botanists consider the simplicity of these flowers to be the result of reduction and specialization ( Subrahmanyam , 1997).

17. (iv) Phylogeny of Amantiferae / Amentifereae Modern phylogenetic studies -based on molecular data have reclassified these plants into several distinct families and orders. The concept of " Amentiferae " is thus more of a morphological grouping rather than one based on evolutionary lineage. Here is an overview of the phylogeny of the major families that were historically grouped under Amentiferae : Phylogenetic Relationships A. Order Fagales - Fagaceae @Phylogeny: Fagaceae is monophyletic and is one of the core families in the order Fagales . They share a common ancestor with other families in Fagales . Betulaceae @Phylogeny: Betulaceae is also monophyletic and closely related to the Fagaceae within Fagales . Molecular data suggest that Betulaceae and Fagaceae share a common ancestor. Juglandaceae @Phylogeny: Juglandaceae forms a distinct lineage within Fagales . It is closely related to the Betulaceae and Fagaceae , but it represents a separate evolutionary path. Myricaceae @Phylogeny: Myricaceae is another family within Fagales , showing a distinct lineage but sharing a common ancestor with the other families in this order. B . Order Malpighiales Salicaceae @Phylogeny: Salicaceae belongs to the order Malpighiales , which is quite distantly related to Fagales . Within Malpighiales , Salicaceae forms a monophyletic group with close relationships to other families in the order based on molecular phylogenetic studies. C . Order Casuarinales Casuarinaceae @Phylogeny: Casuarinaceae belongs to the order Casuarinales . This family is not closely related to the families in Fagales or Malpighiales . The unique morphological and molecular characteristics place it in a separate evolutionary path.

18. Phylogenetic Tree Overview @ Eudicots ├── Rosids │ ├── Fabids │ │ ├── Fagales │ │ │ ├── Fagaceae │ │ │ ├── Betulaceae │ │ │ ├── Juglandaceae │ │ │ └── Myricaceae │ │ └── Other Fabids Orders │ └── Malpighiales │ ├── Salicaceae │ └── Other Malpighiales Families └── Other Eudicot Clades ├── Casuarinales ├── Casuarinaceae └── Other Casuarinales Families  

19. The APG system uses molecular data, such as DNA sequencing, to establish phylogenetic relationships among plant families. Here’s a brief overview of the phylogenetic relationships of these families based on the APG IV system : Fagales : This order is part of the rosid clade and is well-supported by molecular data. The families within Fagales ( Fagaceae , Betulaceae , Juglandaceae , and Myricaceae ) share a common ancestry and are characterized by similar floral structures, including the presence of catkins. Malpighiales : This is a large and diverse order within the rosid clade , and the placement of Salicaceae within this order is based on molecular phylogenetic studies. Salicaceae is distinct from the families in Fagales despite the morphological similarity of having catkins. Casuarinales : Although not commonly highlighted in standard APG literature as a separate order, Casuarinaceae is often included in molecular studies and has been placed in its own order, reflecting its unique evolutionary lineage.  

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