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 Unit – IV Plant Systematics, Chapter - 8 Taxonomy of Angiosperms

Key concepts:
* The term taxonomy was coined by A.P. de Candolle.
* Taxonomy is the science of characterization, identification, nomenclature and classification of organisms.
* Taxonomy purely based on the description of morphological characteristics is called "Alpha Taxonomy".
* Taxonomy that is based on morphological characters, information from embryology, cytology, palynology, phytochemistry etc. is called "Omega Taxonomy".
*  Systems, Types of Classification
* Based on the criteria followed for classification three types of classifications are recognized.
1. Artificial systems
2. Natural systems
3. Phylo genetic systems

* Artificial system is based on morphological characters like habit, colour, number and shape of leaves etc.
e.g.: 1. Theophrastus classified plants into herbs, shrubs and trees in his book Historia plantarum.
2. Linnaeus classified plants into 24 groups in his book Species plantarum.
* Natural system is based on all possible morphological characters and natural relationships between plants.
e.g.: Bentham and Hooker’s system of classification in the book "Genera Plantarum". They classified flowering plants into three classes and 202 natural orders or families.
* Phylogenetic system is based on evolutionary relationships considering primitive and advanced characters.
e.g.: Engler and Prantl’s system.
* Other types of classifications include numerical taxonomy, cyto taxonomy and chemotaxonomy.

 

Semi technical description of a typical flowering plant
* Description of parts of a flowering plant is necessary for characterization, identification and classification of plants.

* Technical terms are used to describe the habit, habitat, vegetative characters (roots, stem and leaves ) and floral characters like inflorescence, flower in general and detail, fruit, seed, pollination etc.
* Floral diagram and floral formula are used to describe the flower precisely.
* The floral formula contains the following 8 elements:
1. Bract present or absent - Br/Ebr
2. Bracteoles present or absent - Brl/Ebrl
3. Symmetry - Actinomorphic (+)/Zygomorphic (%)
4. Sexuality - unisexual male / unisexual female / bisexual
5. Calyx (K)- number of sepals, gamosepalous / polysepalous
6. Corolla (C) - number of petals, gamopetalous / polypetalous.
(In some plants there is no distinction between calyx and corolla hence Perianth is denoted by P)
7. Androecium (A) - number of stamens, adhesion, cohesion if any.
8. Gynoecium (G) - number of carpels, syncarpous/apocarpous condition, superior or inferior ovary.

* A floral diagram provides information about the number of parts of a flower, their arrangement and relation with one another.

 

SOLANACEAE
It is commonly called as potato family. Some of the important species are
Atropa belladonna (Belladona)
Capsicum fruitiscens (chillie)
Cestrum nocturnum (Night queen)
Cestrum diurnum (Day king)
Datura metel ( Thorn apple)
Lycopersicon esculentum (tomato)    

Nicotiana Tabacum (Tobacco)
Petunia alba (Petunia)
Solanum melangena (Brinjal)
Solanum tuberosum (Potato)
Solanum nigrum (Kamanchi)
Withania somnifera (Aswagandha)
* Some of the chief characters of Solanaceae are:
Presence of bicollateral vascular bundles
Petiole adnate to the stem
Axillary or terminal cymose inflorescence (sometimes panicle)
Ebracteolate, actinomorphic, complete, bisexual flowers
Persistent calyx in some species
Gamopetalous twisted or valvate corolla
5 stamens, epipetalous, alternating with stamens
Bicarpellary syncarpous gynoecium with swollen axile placentation, carpels are oblique at 45º
Fruit berry or capsule

Economic importance:
Tomato, brinjal and potato used as vegetables
Belladonna and ashwagandha used in medicine
Petunia, night queen, day king are ornamentals
Tobacco is a source of nicotine and used in cigar making.

 

LILIACEAE:
This family is commonly called as lily family. Some of the important plants are :
Allium cepa (onion)
Allium sativum (Garlic)
Aloe vera ( Aloe)
Asparagus racemosus (satamuli )
Colchicum autumnale (meadow saffron)
Dracaena anguistifolia (red dragon)     
Gloriosa superb (glory lily)
Lilium candidum (lily)
Smilax xeylanica (sarasaparilla)
Yucca Gloriosa (Spanish dagger)

Important characters of the family are:
Perennial herbs with underground stems, tendril climbers, etc.
Adventitious root system. Fasciculated roots in Asparagus.
Stems may be in the form of bulbs, corm, rhizome or weak stemmed tendril climbers.
Leaves are radical or cauline
Inflorescence is solitary cyme or umbel or raceme.
Flowers trimerous, hypogynous and homochlamydeous.
Tepals six in two rows of three each.
Six stamens epiphyllous or free.
Tricarpellary syncarpous gynoecium with trilocular ovary and axile placentaion.
Fruit capsule or berry.
Polyembryony is common in Allium sps.

Economic importance:
Lily, Gloriosa and Asparagus are ornamentals.
Aloe, Smilax, Gloriosa and Asparagus are used in medicine.
Allium cepa is used as vegetable.
Allium sativum used as spice.
Colchicum produces Colchicine used as mutagen.

Posted Date : 29-07-2021

గమనిక : ప్రతిభ.ఈనాడు.నెట్‌లో కనిపించే వ్యాపార ప్రకటనలు వివిధ దేశాల్లోని వ్యాపారులు, సంస్థల నుంచి వస్తాయి. మరి కొన్ని ప్రకటనలు పాఠకుల అభిరుచి మేరకు కృత్రిమ మేధస్సు సాంకేతికత సాయంతో ప్రదర్శితమవుతుంటాయి. ఆ ప్రకటనల్లోని ఉత్పత్తులను లేదా సేవలను పాఠకులు స్వయంగా విచారించుకొని, జాగ్రత్తగా పరిశీలించి కొనుక్కోవాలి లేదా వినియోగించుకోవాలి. వాటి నాణ్యత లేదా లోపాలతో ఈనాడు యాజమాన్యానికి ఎలాంటి సంబంధం లేదు. ఈ విషయంలో ఉత్తర ప్రత్యుత్తరాలకు, ఈ-మెయిల్స్ కి, ఇంకా ఇతర రూపాల్లో సమాచార మార్పిడికి తావు లేదు. ఫిర్యాదులు స్వీకరించడం కుదరదు. పాఠకులు గమనించి, సహకరించాలని మనవి.

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