Fabaceae|Vegetative characters|Floral characters|Economic importance|Class 11 biology скачать в хорошем качестве

Fabaceae|Vegetative characters|Floral characters|Economic importance|Class 11 biology

*Fabaceae (Leguminosae) – The Legume Family* #### *1. Introduction* Fabaceae, also known as Leguminosae, is the third-largest family of flowering plants after Asteraceae and Orchidaceae. It consists of about **770 genera and over 19,500 species**, making it one of the most economically and ecologically important plant families. #### *2. Distribution & Habitat* *Cosmopolitan distribution* (found worldwide except in polar regions). Dominant in **tropical and subtropical regions**. Occurs in diverse habitats: **forests, grasslands, deserts, and wetlands**. #### *3. Morphological Characteristics* ##### *A. Vegetative Features* **Growth Forms**: Mostly *herbs* (e.g., Trifolium – clover), *shrubs* (e.g., Crotalaria*), **trees* (e.g., Acacia*, *Dalbergia*), and **climbers* (e.g., Pisum – pea). **Root System**: Often has *nitrogen-fixing root nodules* due to symbiotic association with Rhizobium bacteria. **Leaves**: *Alternate**, **stipulate* (stipules often modified into spines in *Acacia*). *Compound leaves* (pinnate – *Tamarindus*, bipinnate – *Acacia*, trifoliate – *Trifolium*). *Pulvinus* (swollen leaf base) present in many species, allowing movement (nyctinasty). ##### *B. Reproductive Features* **Inflorescence**: *Racemose* (e.g., Lupinus*), **spike* (e.g., *Medicago*), or solitary flowers. **Flower**: *Zygomorphic* (bilaterally symmetrical). **Perianth**: **Calyx**: 5 sepals, fused (gamosepalous). *Corolla**: 5 petals, arranged in a **papilionaceous* (butterfly-like) structure: *1 standard (vexillum)* – large upper petal. *2 wings (alae)* – lateral petals. *2 keels (carinae)* – fused lower petals enclosing reproductive parts. **Androecium**: Typically **10 stamens**, either: *Monadelphous* (fused into a single tube – *Crotalaria*). *Diadelphous* (9 fused + 1 free – *Pisum*). **Gynoecium**: **Monocarpellary**, superior ovary, single style, and stigma. **Fruit**: *Legume (pod)**, dehiscent along both sutures (e.g., *Phaseolus – bean). Some modified forms: *Lomentum* (constricted between seeds – Arachis – peanut). *Indehiscent pod* (e.g., *Trifolium*). **Seeds**: Non-endospermic, with large cotyledons (food storage). #### *4. Classification & Subfamilies* Traditionally divided into *3 subfamilies* (now often treated as separate families): 1. *Faboideae (Papilionoideae)* – Largest subfamily (~14,000 species). **Distinct papilionaceous corolla**. *Examples**: *Pisum (pea), Glycine (soybean), Cicer (chickpea). 2. *Caesalpinioideae* (~2,200 species). **Zygomorphic but not papilionaceous**. *Examples**: *Cassia*, *Tamarindus*, *Delonix (flame tree). 3. *Mimosoideae* (~3,200 species). **Small, actinomorphic flowers in dense inflorescences**. **Examples**: *Acacia*, *Mimosa*, *Albizia*. #### *5. Economic Importance* **Food Crops**: Pulses: Lens (lentil), Cajanus (pigeon pea), Phaseolus (beans). Oilseeds: Arachis (peanut), Glycine (soybean). Forage: Medicago (alfalfa), Trifolium (clover). **Timber & Industrial Use**: Dalbergia (rosewood), Acacia (gum arabic). **Medicinal Plants**: Glycyrrhiza (liquorice), Clitoria ternatea (used in Ayurveda). **Ornamentals**: Lupinus (lupin), Delonix regia (flamboyant tree). #### *6. Ecological Importance* *Nitrogen Fixation**: Symbiosis with *Rhizobium improves soil fertility. *Pioneer Species**: Help in ecological succession (e.g., *Acacia in arid regions). **Pollinator Support**: Flowers attract bees, butterflies, and birds. #### *7. Special Adaptations* *Myrmecophily**: Some *Acacia species have hollow thorns housing ants for defense. *Xerophytic Adaptations**: *Prosopis (mesquite) has deep roots for desert survival. *Conclusion* Fabaceae is a *highly diverse, economically vital, and ecologically significant* family. Its ability to fix nitrogen makes it crucial for sustainable agriculture, while its species provide food, fodder, timber, and medicine worldwide. #Fabaceae #Leguminosae #Papilionaceae #Biology #PlantClassification #Botany #NCERTBiology #KingdomPlantae #FabaceaeFamily #LegumePlants #FloweringPlants #PeaFamily #BiologyLecture #PlantKingdom #EducationalVideo #PlantTaxonomy #FabaceaeCharacteristics #LegumeSeeds #FabaceaeExamples #PlantMorphology #FabaceaeLifeCycle