What are the salient features and merits of Hutchinson’s system of classification ?

Hohn Hutchinson, a British botanist and formerly the office holder of museum of royal botanical garden, kew, England has given the classification of plants based on the principles followed by Bessey his classification was published in his famous book families of flowering plants in two volumes. Volume-II published in 1926 dealing with dicotyledons and volume-II published in 1934 on monocotyledons.

The system of classification was revised in British flowering plants (1948) and again the second edition of the families of flowering plants (1959) It is underlying principles are more like the besseeyan syatem than the englerian system.

This is phyogenetic system is based on the assumption that:

i) Plants with petals and sepals associated with other floral and anatomical character are primitive and more ancient than the plants without sepals.

ii) Free floral parts are more primitive than the agnate or connate parts.

iii) Spiral arrangement of floral parts sepals petals and stamens are more primitive than cyclic arrangement.

iv) Hermaphrodite condition and free stamens are primitive over the unisexual flowers and connate stamens.

v) A regular or actinomerphic flower is primitive with zygomorphic flowers.

vi) Solitary flower is more primitive than the inflorescenced flowers.

vii) Hypogyny is more primitive than epigyny and perigyny conditions.

viii) A flower with indefinite number of floral parts is primitive over few numbers of floral parts.

ix) Complete flower are primitive than incomplete flowers.

Principle’s of Hutchinon’s Classification:

Hutchinos’s classification is based on flowing principles which has been supported by others. The principles are outlined under 24 point which are as follows:

1. The evolution is both upward and downward, the former tending towards preservation and the later to their reduction and degeneration of characters.

2. Evolution does not necessarily involve call organs at one time or simultaneously.

3. Aquatic plants are derived from terrestrial and saprophytes parasites epiphytes are more recent.

4. Trees and shrubs are more primitive than herbs.

5. Perennials are more primitive than biennials and annuals.

6. Plants with vascular bundles arranged in a ring are more primitive those in which vascular bundlers are scattered.

7. Spiral phyllotaxy is primitive than whorled and opposite phyllotaxy.

8. Dioecious plants are more advanced than bisexual flowers.

9. Unisexual flower are more primitive than bisexual flowers.

10. Petalod flowers are more primitive than bisexual flowers.

11. Gamopetally is more advanced than polypetalae.

12. Zygomorphic flower are more advanced than actinomorphic flowers.

13. Hypogyny is more primitive than perigyny and epigyny.

14. Simple leaves are more primitive than compound leaves.

15. Solitary flower is more primitive than infloresceneed flowers.

16. Spirally imbricate floral parts are more primitive than whorled and valvate arrangement.

17. Apocarpy is more primitive than syncarpy.

18. Polycarpy preceedes oligocarpy.

19. Endospermic seeds with small embryo are more primitive than non endospermic seeds with large embryo.

20. Flowers with numerous stamens are more primitive than those with fewer stamens.

21. Free stamens precede the fused ones.

22. Aggregate fruits are more evolved than single fruit and capsule preceedes berry or drupe.

23. Parietal placentation is more primitive than axial and free central placentation.

24. Trees or arboreal habit are more primitive than climbers are twiners in any one family or genus.

A) Sub-phylum – I – Dicotyledonae

i) Embryo with two cotyledons

ii) Tap root system

iii) Reticulate veination of leaves

iv) Pentamerous floral parts

This sub phylum further divided into two divisions.

Division (I) : Lignosae

i) Trees and shrubs, woody plants.

ii) It includes 54 orders which begins with magnoliales and ends with verbenales.

Order – 1 – Magoliales – (Magnoniaceae)

Order – 2 – Anonales – (Annonaceae)

Order – 6 – Rosales – (Rosaeae)

Order – 7 – Leguminales – (Mimosae, Fabaceae)

Order – 30 – Cucurbitales – (Cucubitaceae)

Order – 33 – Maivales – (Malvaceae)

Order – 52 – Rubiales – (Rubiaceae)

Order – 54 – Verbenales – (Verbenaceae)

Division –II Herbaceae:

i) It includes all herbaceous plants.

ii) Plants may be annuals or binnials or perennials.

iii) This division includes 28 orders which start with ranales and ends with lamiales.

Order – 55 – Ranales – (Rannunculaceae, Nymphaceae)

Order – 59 – Rhoedales – (Papaveraceae)

Order – 60 – Cruciales (Pareitales ) – Cruciferae

Order – 72 – Umbellales – Umbelliferal (Apiaceae)

Order – 76 – Asterales – Compositae (Asteraceae)

Order – 77 – Solanales – (Solanaceae, convolvulaceae)

Order – 78 – Personales – (Acanthaceae, Scorephulariaceae)

Order – 82 – Lamiales – (Labiatae)

SUB –PHYLUM – 2- Monocoty ledonae:

i) Embryo with one cotyledon

ii) Fibrous adventitious root system

iii) Parallel veinationof leaves

iv) Closed and scattered vasular bundles

v) Trimerous flowers

This sub – phylum divided into three divisions

Division – I – Calyciferae:

i) Flowers with distinct calyx and corolla

ii) Sepals green in colour, petals colured variously.

iii) It includes 12 orders, starting with butamales and ends with zingiberales.

Order – 1 – Butamales – (Butamaceae)

Order – 8 – Commelinales – (Commelinaceae)

Order 12 – Zingiberales – (Zingiberaceae; musaceae)

Division – II – Corolliferae:

i) Both calyx and corolla are not distinct in colourantion.

ii) Sepals may be coloured other than green.

iii) Petlas and sepals present in different whorl.

It includes 14 orders begins with liliales and end with orchidales

Order – 13 – Liliales – Liliaceae

Order – 15 Aeales – Araceae

Order – 17 – Amaryllidales – Amaryllidaceae

Order – 21 – Palmales – palmales – palmae (Arecaceae)

Order – 26 – Orchidales – Orchidaceae

Division – III – Glumiflorae

i) Flower with reduced perianth

ii) Neither sepal not petal is distince and reduced to membanous lodicules.

This includes 3 orders and six familes

Order – 27 – Juncales – Juncaceae

Order – 28 – Cyperales – Cyperaceae

Order – 29 – Graminales – Graminae (Poaceae)

Merits of Hutchinson’s Classification:

i) It is most phylogenetic system of classification based on natural characteristic of plants.

ii) This system is based on evolutionary tendencies and interrelationship among angiospermic plants.

iii) Magnoliales representing arborescent plants and ranales representing herbaceaous plants which shows parallel evolution.

iv) Several big orders have been broken into small orders like rosales, paritales, malveles, leguminales etc.

v) Many families have been raised to the rank of orders, leguminosae famile raised to order leguminales.

vi) Reshuffiling or genera and families

vii) Origin of monocots from dicots and placement of first dicot and then monocot families is correct in all respect.

viii) Placing of gymnosperms before angiosperms in flowering plants.