Modern System of Classification
The system of classification is used all types of information i.e. morphology, anatomy, histological, biochemical and DNA analyses. The modern classifications are as follows:
Tackhtazan, Cronquist, Angiosperm Phyllogeny Group (APG) etc.
According to Arther Cronquist, Angiosperm or Magnoliophyta Division is classified into two Classes:
A. Class- Magnoliopsida (Dicotyledon)
B. Class-Liliopsida (Monocotyledon)
A. Class Magnoliopsida (Dicotyledon) has six subclasses (S), 63 orders, 315 families, and around 165400 species. The class has following subclasses:
S1- Magnoliidae
This subclass contains 8 orders, 39 families and about 11000 species. They are most primitive angiosperms. The major characteristics of the members of Magnoliidae subclass are:
Many parted well-developed perianth of tepals Differentiated into sepals and petals but sometimes apetalous The stamens are numerous and mature in a centripetal manner
S2-Hamamelidae
This subclass possesses 11 orders, 23 families and about 3400 species, it is the smallest subclass of dicots. The important characteristics of the subclass are:
The perienth is absent or poorly developed Many are unisexual flower The mature fruit contains single seed
S3-Caryophyllidae
The subclass Caryophyllidae contains three orders, 14 families and about 11000 species. The subclass has following characteristics:
Mostly herbaceous mostly succulents or halophytes Placentation is mostly free central or basal Pollens are tricoplate
S4-Dilleniidae
It contains 13 orders, 78 families, and about 24000 species. The important characteristics are Contain many woody species Centrifugal maturation of stamens and binucleate pollen
S5-Rosidae
The subclass has 18 orders, 113 families, and about 60000 species. It is the largest subclass among the dicotyledons.
Characteristics
The flower has numerous stamens that mature in centripetal sequence. Polypetalous corolla
S6-Asteridae
The sub-class Asterdae contains 10 orders, 48 families and about 56000 species. It is the second largest sub-class of dicotyledons.
Characteristics
The stamens are few and alternate with petals
B. Class Liliopsida (monocotyledon) has five subclasses (S)
S1: Alismatidae
The sub-class has 4 orders, 15 families and 500 species. The sub-class has following
Characteristics:
They are mostly primitive, aquatic or wetland habitats. Most are apocarpous and have trinucleate pollen
S2: Arecidae (4 orders, 6 families, and about 6400 species)
Members of the subclass vary from tiny macroscopic duckweeds to huge woody palms. About 50% of the species are arborescent Stomatal subsidiary cells are usually four
S3: Commelinidae (6 orders, 16 families, and about 16200 species)
Majority of the species are herbaceous Pollen is either trinucleate or binucleate
S4:Zingiberidae (2 orders, 9 families, and about 2800 species) They are mainly tropical
S5: Liliidae (2 orders, 19 families, and 28000 species)
They are highly developed for pollination Majority are terrestrial or epiphytic herb Leaves are generally linear with parallel veined or broad to netted veined
DIVISION : MAGNOLIOPHYTA (Flowering plants)
CLASS : MAGNOLIOPSIDA (Dicotyledon)
Subclass : Magnoliidae
Order I : Magnoliales Family 1 :Annonaceae
Order II : Nymphiales Family 2 : Nymphiaceae
Subclass : Hamamelidae
Order III : Urticales Family 3 :Moraceae Family 4 :Cannabaceae Family 5 : Urticaceae
Order IV : Myricales Family 6 :Myricaceae
Order V : Casuarinales Family 7 :Casuarinaceae
Subclass : Caryophyllidae
Order VI : Caryophyllalaes Family 8 :Cataceae Family 9 : Amaranthaceae Family 10 : Chenopodiaceae
Subclass : Dilliniidae
Order VII : Theales Family 11 : Theaceae Family 12 : Clusiaceae Order VIII : Malvales Family 13 :Malvaceae Family 14 : Malvaceae
Order IX : Violales Family :Cucurbitaceae Family :Caricaceae
Order X : Capparales Family 15 : Brassicaceae Family 16 : Moringaceae
Subclass : Rosidae
Order XI :Rosales Family 17 : Rosaceae Order XII : Fabales Family 18 : Fabaceae Family 19 : Rutaceae Family 20 : Meliaceae Family 21 : Anacardiaceae Order XIII : Apiales Family 22 : Apiaceae Order :Solanales Family 23 :Solanaceae Family 24 :Convulaaceae Family 25 :Lamiaceae Order XIV :Asterales Family 26 : Asteraceae
CLASS: LILIOPSIDA (Monocotyledon)
Subclass: Arecidae Order XV : Arecales Family 27 : Arecaceae Order XVI : Arales Family 28 : Aracae
Subclass: Commelinade Order XVII : Poales Family 29 : Poaceae
Subclass: Zingiberidae Family 30 : Sterlitziaceae Family 31 :Musacae Family 32 : Zingibiracae
Subclass: Liliidae Order XVIII : Liliales Family 33 :Liliaceae Order XVIV : Orchidiales Family 34 :Orchidiaceae
Table Differences between Magnoliopsida (Dicotyledon) and Liliopsida (Monocotyledon)
Characters Magnoliopsida Liliopsida (Dicotyledon) (Monocotyledon)
1 Cotyledon Two one 2 Endosperm Absent Present 3 Leaves Reticulated venetation Parallel venetation 4 Root system Tap root Fibrous roots 6 Growth form May be herbaceous or woody Mostly herbaceous, few are arborescent 7 Vascular bundle Usually arranged in ring form Arranged in scattered form 7 Cambium Present Absent 8 Primary vascular bundle In a ring form Arranged in scattered form
9 Secondary growth Present Absent
10 Floral parts Parts are usually in four or Parts are three or multiple five of three
Angiosperm Phylogenic Group (APG)
The Angiosperm Phylogeny Group, or APG, refers to an informal international group of systematic botanists who came together to try to establish a consensus on the taxonomy of flowering plants (angiosperms). The term angiosperm is derived from the Greek words angeion and sperma, meaning vessel and seed, respectively. Contrasting to gymnosperms (naked-seeded plants), in which the seeds are usually borne on ovulate cone scales, in angiosperms the seeds are protected in vessel called the carpel, which matures into fruit.The APG system of plant classification is the first, now obsolete, version of a modern, mostly molecular based system of plant taxonomy which was published in 1998.
Member institute of APG 1. Swedish Academy of Sciences 2. Uppsala University; 3. Stockholm University 4. Royal Botanic Gardens, Kew 5. University of Maryland; 6. Cornell University 7. University of Florida 8. Florida Museum of Natural History 9. Harvard University Herbaria 10. University of Missouri-St. Louis and 11. Missouri Botanical Garden
Clade
In the terms of biological systematics, a clade is a single "branch" on the “tree of life. It is a grouping of organisms which have a common ancestor and the grouping is made on the basis of presumed evolutionary history. It is a group of organismssharingfeaturesthatreflect a commonancestor or descent.
Figure Graphical sketch of clade
Clades of Angiosperm
1. Monocots 2. Commelinoids 3. Eudicots 4. Core eudicots 5. Rosids 6. Eurosids I 7. Eurosids II 8. Asterdis 9. Euasterdis I 10. Euasterdis II