Core Features and Differences of Asteraceae, Brassicaceae, and Poaceae
Angiosperm is a diverse group. They have stems, roots and leaves and can bear flowers. They have seeds enclosed within the ovary. The angiosperm family includes:
Asteraceae
Brassicaceae
Poaceae
Asteraceae
Characteristics of Asteraceae
They have the following characteristic features:
These are herbs, shrubs or trees. Most of them are xerophytes, hydrophytes and semi-aquatic.
Taproots are modified into tubers.
The stem could be erect, hairy, woody or prostrate. It might sometimes contain latex.
The leaves may be radical, petiolate, exstipulate,
Flowers are tubular or ligulate, bisexual or unisexual, usually dithecous, filament free with united anthers.
Androecium is absent.
Gynoecium is either absent or present.
The seed is endospermic.
The fruit produced is cypsela.
Economic Importance of Asteraceae
Food
Family Asteraceae is an important source of food. The leaves and roots of a couple of angiosperms like garden lettuce and Jerusalem artichoke are edible.
Oil
The seeds of angiosperms are a crucial source of oil.
Medicines
Most of the plants that belong to the Asteraceae family have some of the best medicinal values. For eg., Solidago is employed in dropsy, artemisia yields santonin, the juices and roots of a couple of plants are utilized in bowel disorders and have a cooling effect..
Rubber
Taraxacum and Solidago leavenworthii are a crucial source of rubber.
Insecticide
The capitula of Chrysanthemum roseum is dried and its powder is employed as an insecticide.
Brassicaceae
Characteristics of Brassicaceae
Following are the important characteristics of family Brassicaceae:
These are generally herbs, annuals, biennials, or shrubs.
The taproots are swollen due to food storage.
The stem is erect, herbaceous, and rarely woody.
Leaves are alternate, opposite, simple and exstipulate
Economic Importance of Brassicaceae
Food
The plants of this family are cultivated as vegetable crops. For eg., Brassica oleracea var. Botrytis, Brassica oleracea var. Caulorapa.
Oil
The seeds of the plants of these families are used to extract mustard oil that is extensively used in cooking. For eg., Brassica campestris
The cake left behind after the extraction of oil is employed as cattle feed and fertilizer.
Medicines
The leaves and shoots of plants are utilized in asthma, cough and bleeding piles. They also act as an appetizer and stimulant. The seeds are wont to treat bronchitis and fever. The flowers help in paralysis and impotency.
Ornamentals
Few plants like Iberis amara, Hesperis, Alyssum, bear beautiful flowers and are used for ornamental purposes.
Poaceae
Characteristics of Poaceae
Following are the important characteristics of Poaceae family:
It might be herbs or shrubs, annuals or perennials, and sometimes tree-like.
The roots are often fibrous, adventitious, branched or stilt.
The stem could also be underground as in rhizomes, cylindrical with conspicuous nodes and internodes, woody or herbaceous.
The leaves are alternate, simple, exstipulate, and distichous. The leaf base forms a tubular sheath.
The seeds are endospermic and monocotyledonous.
Fruits include caryopsis, nuts or berry.
Economic Importance of Poaceae
Food
The plants of this family are a crucial food source. For eg., cultivated rice , common wheat , cereal oat (oats), corn (Maize).
Grasses like Panicum, Bermuda grass , Cymbopogon, and Poa are used as fodder.
Sugar
Jaggery and sugar are obtained from Saccharum officinarum.
Building Material
Species of Bambusa are used for scaffolding and thatching of huts.
Aromatic Plants
Many sorts of grass like Vetiveria zizanioides yield scented oil from its roots. The roots are also used to weave curtains.
Medicines
Plants such as Phragmites karka, Claviceps purpurea, Cymbopogon schoenanthus have medicinal values.
FAQs on Asteraceae, Brassicaceae, and Poaceae: Essential Angiosperm Families
1. What are the main characteristics of the Asteraceae family?
The Asteraceae family, also known as the sunflower or composite family, is one of the largest angiosperm families. Its key characteristics include:
- Inflorescence: A highly specialised capitulum or head, where numerous small flowers (florets) are arranged on a common receptacle.
- Florets: Two types of florets can be present: tubular (disc florets) and ligulate (ray florets).
- Stamens: Typically five stamens that are syngenesious, meaning their anthers are fused into a tube while the filaments remain free.
- Gynoecium: A bicarpellary, syncarpous ovary which is inferior.
- Fruit: A single-seeded dry fruit called a cypsela, often with a persistent calyx (pappus) that aids in wind dispersal.
2. What distinguishes the Brassicaceae family from other angiosperm families?
The Brassicaceae family, or mustard family, is distinguished by a unique combination of floral and fruit characteristics. The most important features are:
- Corolla: Four petals arranged in the form of a cross, known as a cruciform corolla. This is a primary diagnostic feature.
- Stamens: Six stamens arranged in a tetradynamous condition, with four long inner stamens and two short outer ones.
- Gynoecium: A bicarpellary, syncarpous, superior ovary with a false septum called the replum.
- Fruit: A type of capsule called a siliqua (if long and narrow) or silicula (if short and broad), which dehisces to expose the seeds on the replum.
- Chemistry: The presence of sulphur-containing compounds (glucosinolates) that give many plants in this family a pungent or spicy taste (e.g., mustard, radish).
3. Can you provide some common examples of plants from the Poaceae family?
The Poaceae family, also known as the grass family, is arguably the most economically important plant family. Common examples as per the NCERT syllabus include:
- Cereals: Wheat (Triticum aestivum), Rice (Oryza sativa), Maize (Zea mays), Barley (Hordeum vulgare), and Oats (Avena sativa).
- Millets: Sorghum (Jowar), Pearl Millet (Bajra), and Finger Millet (Ragi).
- Sugar Source: Sugarcane (Saccharum officinarum).
- Structural Use: Bamboo species, which are a type of giant grass.
- Fodder: Various pasture grasses used for animal feed.
4. How do the floral structures and inflorescence of Poaceae, Brassicaceae, and Asteraceae differ?
The inflorescence and floral structures of these three families are highly distinct and show different evolutionary strategies:
- Poaceae (Grasses): The inflorescence is a compound spike, often called a spike of spikelets. Each spikelet contains one or more small, wind-pollinated flowers (florets) enclosed by bracts called glumes. The flowers themselves are simple, lacking distinct sepals and petals, and are instead enclosed by a lemma and palea.
- Brassicaceae (Mustards): The inflorescence is typically a raceme or corymb. The flowers are conspicuous, bisexual, and actinomorphic with a cruciform corolla (4 petals), tetradynamous stamens, and are generally insect-pollinated.
- Asteraceae (Sunflowers): The inflorescence is a capitulum or head, which functions as a single pollination unit. It consists of multiple small florets (ray and/or disc) packed onto a receptacle. This arrangement is highly efficient for attracting pollinators. The flowers are epigynous (inferior ovary).
5. What is the economic significance of the Asteraceae and Brassicaceae families in India?
Both families have immense economic importance in India. Brassicaceae is primarily valued for:
- Edible Oils: Mustard (Brassica juncea) is a major source of cooking oil.
- Vegetables: It provides numerous vegetables like cabbage, cauliflower, broccoli, radish, and turnip.
- Condiments: Mustard seeds are used as a spice.
Asteraceae is important for:
- Edible Oils: Sunflower (Helianthus annuus) and Safflower (Carthamus tinctorius) are key oilseed crops.
- Food: Lettuce (Lactuca sativa) is a common salad vegetable.
- Ornamentals: Marigold (Tagetes), Chrysanthemum, and Dahlia are widely cultivated for decoration and religious ceremonies.
- Medicinal: Some species like Artemisia are sources of medicinal compounds.
6. Why is the Asteraceae family considered one of the most evolutionarily advanced among dicots?
The Asteraceae family is considered highly advanced due to several successful evolutionary adaptations:
- Specialised Inflorescence: The capitulum acts like a single large flower, making pollination highly efficient by attracting more pollinators with less energy investment per flower.
- Fused Anthers (Syngenesious Condition): The fusion of anthers into a tube around the style creates a unique 'pollen-pump' or 'plunger' mechanism for precise pollen presentation.
- Inferior Ovary: The ovary is located below other floral parts, providing it with better protection against herbivores and external damage.
- Effective Seed Dispersal: The development of the pappus (modified calyx) into hairs or bristles allows the cypsela fruit to be dispersed effectively by wind over long distances.
- Chemical Defences: Production of secondary metabolites protects these plants from many pests and diseases, contributing to their widespread success.
7. What are the key differences in the fruit types found in the Asteraceae, Brassicaceae, and Poaceae families?
The fruit in each family is a key diagnostic feature that reflects its unique ovary structure and evolutionary path:
- Asteraceae: The fruit is a Cypsela. This is a dry, single-seeded fruit that develops from a bicarpellary, syncarpous, inferior ovary. A key feature is that it is often crowned by the persistent pappus (modified calyx).
- Brassicaceae: The fruit is a Siliqua or Silicula. This is a type of capsule that develops from a superior, bicarpellary ovary and is characterised by a false septum called the replum, to which the seeds are attached.
- Poaceae: The fruit is a Caryopsis. This is a type of single-seeded, dry fruit where the fruit wall (pericarp) is completely fused with the seed coat (testa). This is the characteristic 'grain' of all cereals like wheat and rice.
