Phytogeography is concerned with all aspects of plant distribution, from the controls on the distribution of individual species ranges to the factors that govern the composition of entire communities and floras.
2. Phytogeography - Definitions:
• Phytogeography (from Greek, phyto
= "plant" and geografía =
"geography" meaning also
distribution)
• Phytogeography is concerned with
all aspects of plant distribution,
from the controls on the distribution
of individual species ranges to the
factors that govern the composition
of entire communities and floras.
3. • Phytogeography is defined by Good (1964) as
‘that branch of botany that deals with the spatial
relationships of plants both in the present and
the past’
• Phytogeographical areas are governed by the
world’s climatic belts and Phytogeography is
concerned with the floristics of the common pool
resulting from historical factors; ecology is
concerned with the segregation of species within
the common pool by environmental factors
(Wickens 1976).
• According to D. Chattarjee (1962)
A phytogeographical region is defined as an area of
uniform climatic conditions and having a
distinctly recognisable type of vegetation
4. Distribution of plants is mainly
controlled by climatic factors.
• Temperature, Altitude, Precipitation, Atm
moisture, Light intensity and duration.
• Type of soil.
• Biotic factors play an important role in
distribution and establishment of species.
• The great area of Indian subcontinent has
wide range of climate and corresponding
diversity in the vegetation.
5. India has been divided into the following
botanical zones by D. Chatterjee (1962)
• (1) Western Himalayas,
• (2) Eastern Himalayas,
• (3) Indus plain,
• (4) Gangetic plain,
• (5) Central India,
• (6) Deccan,
• (7) Western coasts of Malabar,
• (8) Assam, and
• (9) Bay Islands of Andaman
and Nicobar.
6. Flora of Western Himalaya:
• This region comprises
north and south
Kashmir, part of
Punjab and Kumaon
region of Uttaranchal.
• Average annual rainfall
in the region is 100-
200 cm. The region is
wet in outer southern
ranges and slightly dry
in the inner areas.
• At high altitudes,
snowfall occurs during
winters. The region is
subdivided into three
zones.
9. Submontane (lower, tropical
and subtropical) zone:
• This zone includes outer Himalayas i.e.
regions of Siwalik Hills and adjoining
areas from 300 to 1500 m altitude.
• Average annual rainfall of the zone is
around 100 cm.
• The vegetation consists of subtropical
dry evergreen, subtropical pine and
tropical moist deciduous forests.
10. Temperate (montane) zone:
• This zone extends in the western Himalayas
between the altitudes 1500 and 3500 m.
• The climate is wet between the altitudes
1500 and 1800 m and is drier at higher
altitude.
• The vegetation consists of wet forests,
Himalayan moist and Himalayan dry
temperate forests.
11. Alpine zone:
• This zone extends between 3500 m and
5000 m altitudes.
• The rainfall is very scanty and climate is
very cool and dry.
• The vegetation consists of alpine forests.
12. • The vegetation of this region consists of chiefly
Acacia modesta, Euphorbia royleana, Olea,
Bombax ceiba, Themada, Chrysopogon
serrulatus, Bauhinia vahlii, Shorea robusta,
Cassia fistula, Lagerstroemia parviflora, Murraya
keonigii, Zanthoxylum alatum, Terminalia,
Anogeissus latifolia, Toona ciliata, Zanthoxylum
alatum, Adhatoda, Carissa, Rosa, Rubus,
Syzygium, Crataegus, Diospyros, Emblica, Picea,
Pinus wallichiana, Cedrus deodara, Rhamnus,
Salix, Berberis, Smilax, Arundinaria, Fraxinus,
Fragaria, Viola, Artemesia, Rheum, Sedum,
Betula, Anemone, Saxifraga, Geranium, etc.
13. Flora of Eastern Himalayas:
• Eastern Himalayas comprises of
mountain ranges from Sikkim to
Arunachal.
• The climate is warmer and
wetter than in western
Himalayas.
• Tree line and snow line are
higher by about 300 m than in
the western Himalayas.
• It is botanically best known part
of this region. More than 4,000
sp. of phanerogams belonging to
160 families and lower plants
are found in this region.
18. This region is also divided into
three zones.
• Submontane (lower, tropical and subtropical)
zone: This zone extends from the foothills up to the
1850 m altitude. The climate is nearly tropical and
subtropical. The vegetation consists of subtropical
broad-leaved forests, pine forests and wet temperate
forests.
• Temperate (montane) zone: The zone extends from
1850 m to 4000 m altitude, about 500 m higher
than in the western Himalayas. The vegetation
consists of typical temperate forests with oaks
and Rhododendron at lower and conifers at higher
altitudes.
• Alpine zone: This zone extends from 4000-5000 m
altitude. The climate is very cool and dry. The
vegetation consists of alpine forests.
19. Flora of Indus Plain:
• The area comprises of Gujarat, Delhi,
Rajasthan, Haryana and Punjab.
• It is the dry region from plains to Mt.
Abu; deserts and irrigated lands.
Rainfall is very low in extremely dry
areas.
• The climate has very dry and hot
summers alternating with dry and
cold winters.
• The annual rainfall is generally less
than 70 cm and may be 10-15 cm in
some areas.
• Most of the region is desert today
though it had dense forests about
2000 years ago that were destroyed
due to biotic factors particularly
extensive cattle grazing.
• The vegetation today consists of
tropical thorn forests and grasslands
in some areas.
20. • Indus plain can be divided into 3
types of vegetation as
tropical dry deciduous,
tropical thorny and
dry shrubs.
22. Flora of Gangetic Plain:
• The area extends from east
Delhi to Sundarbans of
Bengal passing through
Bihar, Orissa and U.P. It
includes dry deciduous
(Scrub) and Moist deciduous
vegetation. Sometimes the
Indus region and Gangetic
region, because of similar
type of vegetation, is called
as Indo Gangetic plain.
• Average annual rainfall
ranges from 50 cm to 150
cm from east to west.
• The Gangetic plain divided
into upper Gangetic plain,
Lower Gangetic plain and
Sundarbans.
23. • Dry deciduous forests are common
• Capparis, Dalbergia, Acacia species are very common.
24. Lower Gangetic plain:
• The vegetation is dominated by Shorea
robusta, Artocarpus, Lagerstroemia,
Ptersopermum, Bombax, Ehertia, Adhatoda,
Murraya koenigii, Pogosternon, Aegle
marmelos, Holoptelea, Areca, Borassus,
Pagostemon etc.
25. Upper Gangetic plain:
• The vegetation is dominated by Acacia
nilotica, Balanites, Jatropha, Flacourtia,
Capparis decidua, Butea monosperma,
Madhuca, Zizyphus, Dalbergia, Phoenix,
Nyctanthes, Woodfordia, Adhatoda,
Terminalia, Prosopis, Tinospora, Vitis,
Cocculus, Ixora, Carissa, Hemidesmus and
many types of grass.
26. Sunderbans
• The largest mangrove forest of the
world is of sunderbans covering
and area of over 15,000 sq. km.
• The area has sea creepers and
swampy islands.
• The main vegetation includes
Typha elephantine (elephant
grass), Pharagmites karka (reed),
Pandanus, Alpina, Ipomoea biloba,
Bruguiera con ugata, Kandelia.
candel, Heritiera, Ceriops,
Aviecnnia officinalis, Aegiceras,
Sonneratia, Nipa fruiticons,
Pheonix paludosa, Cocos nucifera,
Rhizophora mucronata, Acanthus
illicifolius, Panicum repens, Sueda
maritima, Salicornia, Allophylus,
Tamarix, Hygrophila, Derris etc.
27. Central India
• This region comprises part of Orissa,
Madhya Pradesh, Vindhyan region
and Gujrat.
• The areas are mostly hilly with some
places at 500-700 m altitude.
• The average annual rainfall is 100-
170 cm.
• Biotic disturbances are very common
in this region resulting in degradation
of forests into thorny forests in the
open area.
• The vegetation consists of tropical
moist deciduous forests, chiefly Sal
forests in areas of annual rainfall
above 150 cm and mixed deciduous
forest in areas of 125-150 cm
annual rainfall. Tropical thorn forests
are found in the areas of annual
rainfall below 125 cm.
28. Flora of Deccan:
• Deccan includes entire peninsula
South of Ganges and east of Malabar.
• The region comprises southern
Peninsular India from southern
Madhya Pradesh up to Kanyakumari
excluding the Western Ghats.
• The average annual rainfall in the
region is about 100 cm.
• The vegetation consists of tropical dry
evergreen, dry deciduous and swamp
forests.
• The important trees are Michelia
champaca, Dillenia aurea, Chloroxylon
swetenia, Cedrela toona, Santalum
album, Pterocarpus sentalinus,
Soyamida, and tree ferns etc.
29. • Deccan is characterized by presence of “black
cotton soil”. Common planes of this soil are
Hibiscus, Cassia auriculata, Acacia arabica,
Parkinsonia aculeata, Calotropis procera,
Zizyphus numularia, Jatropha grandiflora etc.
• The vegetation of Coromandal subregion is same
in Deccan except some estuarial and mangrove
plants such as Brugiera, Ceriops, Avicinnia etc.
Other plants are Mimusops, Garciia, Chloroxylon
swietenia, Strychnos nux-vomica etc.
30. Flora of Malabar:
• Area of Malabar includes Kerala,
Maharashtra, Gujarat and Karnataka. Hill
areas of western ghats are also included in
this zone.
• Generally, the plants are distributed into:
(a) Temperate evergreen
forests,
(b) Subtropical evergreen
forests,
(c) Tropical evergreen
forests,
(d) Tropical semi-
evergreen forests,
(e) Tropical deciduous
forests, and
(f) Mangrove forests.
31. Flora of Assam:
• The area includes Valleys of Brahmputra, Jaintia,
Khasi and Garo hills, Mishmi hills, North
Himalayas, Santosh River, Naga, Cachar and
Mizo hills, Mizoram, Meghalaya, Nagaland,
Manipur, Tripura and Assam region.
• Good rainfall, dense vegetation is characteristic
of this area.
• The vegetation is richest in the world except
Khasi hills region.
• The vegetation consists of tropical evergreen and
wet temperate forests in the lower plains while
hilly tracts up to 1700 m altitude have
subtropical pine forests
33. Andman and Nicobar
• This region includes
Andman and Nicobar
Islands. The climate of
the region is warm
and humid with very
high temperature and
annual rainfall. The
vegetation consists of
littoral mangrove,
evergreen, semi-
evergreen and
deciduous forests.
