THE FLORA

5.0. THE FLORA

5, I, Introduction

Mangroves are tropical and subtropical littoral plants

growing at the interface between the land and the sea.

They grow on clayee soil which is flat and sloping gentIy

(mud-flats) and in the region where tidal action brings in

water regularly. Indian mangroves are distributed in about

6,740 sp km area(Krishnamurthy et al., 1987).

constituting 7 % of the world mangroves and 8% of the

total Indian coastline. The Indian mangroves are one of the

major forests of the south east Asia. More than 50 species

mangrove plants occur here, making the flora rich but with

uneven distribution. There are three different types of

mangroves in India Viz. deltaic, backwater-estuarine and

insular categories. The deltaic mangroves occur along the

east coast (Bay of Bangal) where the mightily rivers ( the

Ganges, Mahanadi, Godavari, Krishna and Kaveri) make

the deltas. The back water estuarine type mangroves exist

in the west coast (Arabian sea ) which is characterised by

typical funnel shaped estuaries of major rivers (the Indus,

Narmada and Tapti) or their backwaters, creeks and neritic

inlets. The insular mangroves are present in the Andaman

and Nicobar islands where many tidal estuaries, small

rivers, neritic islets and lagoons support a rich mangrove

flora (Gopal and Krishnamurthy 1993) ?'tie perennial

suppIy of freshwater and the constant admixture with sea

water through tides dong the coast and up the mouths of

the rivers has resuIted in an extravagant richness and

diversity.

India is very rich in plant diversity and is recognized

as one of the twelve mega diversity regions of the worId

(Vavilov,l951) . The present satellite based estimate of

mangroves is 4460 sq. k m which indicate loss of about

2280 sq. km. (Nayak, 1996);. Approximately 16 mangrove

species have been documented on the Gujarat coast; while

Maharashtra has about 28, Goa 20 and Karnataka 21.

I*

The Kerala coast has 14 species and Lakshadweep has

four.

The important mangrove families represented in India

are Avicenniaceae, Combretaceae, Rhizophoraceae and

Sanneratiaceae. The mangrove vegetation of Kerala covers

an area of about 17 sq km spreading the entire backwater

systems, lagoons and some of the intertidal areas of Cochi,

Vembanad, Quilon, Thiruvanathapurarn, Ka yamlculam.,

Kannur, Kozhikode and Kattayam. The dominated species

are A Yicennia officinalis, Auicennia marina, Bruguiera

cylind rica, Bruguiera parvzflora, Bruguiera g y mno rhiza,

Rhizopkora apicu Eata, Rhizophora mucronata, Sonnerutiu

caseolaris, Ceriops tagal, cerberu martghas, Dolichandrone

spthesia, Acanthus ilicifo Eius and Derris heterop hy lla

(Bmerjee, 199 1).

5.2. Review of Literature

Taxonomy of mangrove vegetation is not free from

confusion. There are frequent changes in nomenclature of

species and Genera. This is further made difficult as the

same plant is identified differently by different workers in

different areas. The taxonomical problems posed by some

of the mangrove plants are puzzling, as certain species also

produce hybrids and morphologically they show

similarities to more than one species of the same genus.

This difficulty, to a certain extent in, in Indian species has

been overcome by publishing an identification manual for

the mangroves found in India by the Botanical Survey of

IndiaIHanerjee, 1989). According to , this manual Indian

mangrove comprise approximately 59 species of 41 genera

belonging to 29 families. Of these 34 species in 21 genera

and 21 families occur in mangrove and tidal vegetation

along the east coast and about 25 mangroves along the

west coast.

The plant taxonomy of the Indian mangrove forest

types has been described by several workers. The first

systematic comprehensive account of the Sundarban

vegetation was given by Prain (1903). Blatter (1905, 1908)

, Cooke (1908) and other earlier workers divided the

mangroves into four zones, namely a) coastal sea water

and semifluid mud, b) salt marshes along the coast c) salt

marshes of the tidal creek and d.) interior drier marshes.

Gamble (1915), Curtis (1933) described the plant

taxonomy of the Indian mangrove forest types. The

mangrove forests cannot be regarded as climax or pre

climax types. However it is necessary to undertake a

thorough and systematic study of the successional stages

(Champion 1936). Cornwell (1937) and Navalkar (195 1)

described the plant taxonomy of the Indian mangrove

forest type. Navalkar (1951) , Puri and Jain (1957) and

Qureshi (1957) followed similar methods based on tidal

flow, soil salinity and nature of the communities.

Champion and Seth (1968) while f"lxing the forest type of

India, placed the tidal forests under primary seral type of

the moist tropical seral formations. Blasco (1975) has

made some studies on the tidal inundations along the

cauvery delta for different mangrove species. A n attempt

has been done by Blasco (1975) depicting the different

successional stages of mangroves in India. Untawale

(1980) reported present status of the mangroves along the

west coast of India In Kachchh mangorves Sonneratia,

Rhizophora and Ceriops are pushed in to vulnerable and

Aegiceros in to endangered category (Anjali et al; 1997)

Studies on Avicennia marina by Gujarat Institute Desert

Ecology (GUIDE), Bhuj on western mangroves were done

by Singh e t al; ( 1 999). A detailed study of coastal mangrove

ecosystem of Karnataka state was done by Ananda Rao

e tal (2000). Vivek Kulkarni (2002) reported conservation

aspect of Indian mangroves.

The west coast of Malabar region was thoroughly

botanised from the time of Rheede (1678- 1693), Wight

(1838-18531, Hooker et al; (1872-18971, Bourdillon (1893),

Rama Rao (1914), Gamble and Fisher (1915-1936) etc.,

contained references of plants available in this part of the

country. Gamble's (19 1 5- 1935) work also record rich

mangrove vegetation along the Kerala coast line. In Kerala

there was a mention of occurrence of woody species of

mangroves even in the beginning of this century till 19 14

in literature; Troup (1921) gave references about

Mangroves of Kerala , which was again cited by Waheed

Khan (1959). The study of Thomas (1962) at Veli ,

Mohanan 1981 at Quilon, Ramachandran et al (1986) at

Kumarakom and Chand Basha (1991 and 1992) through

out Kerala clearly reveals the existence of true mangroves

and the present: nature of isolated patches of' mangroves

found in the state of Kerala. Mohan Das(l993)studied the

comparative account of flora of Kumarakom and Asramom

mangroves. Jisha (2002) studied the flora of

Ayiramthengu mangroves.

5.3. Materials and Methods

The plant specimens were collected in tluplicate. The

herbar-ium specimens were prepared raccording to

international standards (Fosberg and Sachet, 1969 ; Jain

and Rao 1977; Lawrence 19 5 1 ) . They were identified with

the help of literatures like Gamble and Fisher ( 19 15- 1936)

and Tomlinson (1986) and authentic specimens kept in

different institutions . Whenever required field

measurments, field sketches etc, were made.

5.4. Observation and Results

The following plants were observed in the

Ayiramthengu mangrove area during the present study

period. A s the present study provides original

photographs, the life colour can easily be understood

Plate I 1 to X).

I. True Mangroves

Species

1. Aegiceras cornicuZcrtum L.

2. Avicenniu officinalis L,

3. Bruguiera cy lindricu L.

4. Excoecaria agallocha L.

5 . Lumnitzera racemosa Wil ld.

6. Rhizophora mucronata Lcunk.

Fami la

Myrsinaceae

Avicenniaceae

Rhizophoraceae

Euphorbiaceae

Combretaceae

Rhizophoraceae

11. Mangrove Associates and Marshy plants

Species

1. Acanthus €NcCfoZ€us Linn.

2. Acrostichum aureum Linn.

3. Cerebera odollam Gaertn.

4. Clerodendrum inerme Gaertn.

6. Crotalaria sericea R e l .

7. D e d s uliginosa Benth

8. Epaltes diva&cata Cuss.

9. Fimbristylis ferruginea Vahl.

10. Crotalaria striata DC.

12. Mariscus juvanicus (Houtt)

M e m el Metcqff

13. Ipomaea pes-cuprae L.

14. Sida corduolia Lfnn.

Family

Acanthaceae

Pteridaceae

Apacynaceae

Verbenaceae

Verbenaceae

Papiloneaceae

Papiloneaceae

Asteraceae

Cyperaceae

Papiloneaceae

Euphorbiaceae

Cyperaceae

Rhizophora mucronata Lamk. PLATE

Aegiceras corniculatum L. PLATE

T!'

Avicennia officinalis L.

Excoecaria agallocha L. PLATE

. .

Lumnitzera racemosa Willd.

Mangrove Associates Clerodendrum inerme Gaertn.

PLATE

Derris uliginosa Benth.

PLATE - Cerbera odollam- Gaertn.

- Acrostichum aureum Linn.----

PLATE - Premna latifolia Roxb.

VII

~canrhus ilicifolius Linn.

PLATE VIII .

Other Plants in the Mangrove area v Y

Crotalaria striata DC. Crotalaria sericea Retz.

v Agyneia bacciformis Mariscus javanicus

7

Calophyllum inophyllum L.

. --

F- !!'a Fimbristylis fermgnea

PLATE IX Y

Ipomaea pes-caprae L.

Pennisetum polystachyon Linn;

PLATE

Thespesia populnea Sol#

Sida cordifolia Linn.

A Epaltes divaricata Cass.v

14. Sida corduolia Lhn. klalvaceae

15. Pennisctum polystachyon S c h Poaceae

16. Thespesiu popuhea Malvaceae

Soland ex. corr

17. Calophyllum inophyllum Llnn. Clusiaceae

Taxonomic and Ecologic Observations of the Plants of

the Aviramthengu Mangrove Area

Eu Mangroves

Occurrence: Gregarious on the banks of tidal streams, and

intertidal zones, often forming pure zones along the muddy

flats, usually confined to sheltered banks not subjected to

strong tides. Often associated with Sonneratia caseolaris

and Auicennia alba ( Fig .on Plate 111)

Growth form: Small evergreen bushy shrub up to two to

five meters high, stems much brimched with brownish -

green bark and broom shaped. Sap wood white, heart

wood with a pinkish tinge.

Buttrewes or Aerial Roots: Nil but base of trunk has

cot~spicuous white round lenticels .

Leaf : Coriaceous, entire, glabrous, alternate, petioled, pale

green above, somewhat glaucous beneath, base cuneate,

mid nerve strong, the lateral nerve numerous, slender,

petiole very short, stout. Salt excreting glands is seen on

the abaxial surface.

Inflorescence: Umbellate terminal or axillary flowers.

Flower: 1,5 to 2 c.m. long, white, fragrant, subsessile, leaf

opposed or rarely axillary umbels, pedicels, 0.63 to 1.2 em.

exserted.

Fruit: 6 to 8c.m. long, falcately curved, very sharply

pointed, coriaceous, green yellowish brown with persistent

imbricate calyx, mesocarp spongy; epicarp rnembranous,

hypocotyl3 - 4 c.m. long.

Flowering: March to December

Fruit in% July to February

Regeneration; Through sickle shaped fruits. The mature

fruits after detachment lie on the mud surface to give rise

to seedlings. One can observe innumerabl t: seedlings

underneath the mature bushes, not away from the parent

plant because the fruits are not truly viviparous and

cannot take root where the tides are strong.

Economic use : Used as fuel.

+ I1 Aviceanla officinalis L.

Verbenaceae (A vice nniaceae)

Occurrence: Frequent along the muddy coast and in the

intertitiel regions of creeks and channels of the mangrove

forests. I t prefers less saline areas when corn~xired to other

species. Usually found in association with Rhizophora

mucronata ( Fig. on Plate 111).

Gxowth form : Tree form with good crown growth reaching

up to a height of 8 m. Usually found interior in the tidal

wetlands. Occasionally faces the riverine banks .

Pneumatophores: Plenty , pencil like aerial roots

negatively geotropic , helps in anchorage and exchange of

gases takes place through the lenticels . Presence of salt

excreating glands on the leaves.

Leaf: 6- 10 X 6.5 cm, opposite obovate or broadly ovate - oblong , coriaceous, dark green above , silvery papillose

beneath , acute at apex, main nerves 4-6 pairs with

reticulate venation between petioles 0.6-0.8 cnl.

Inflorescence: Terminal or axillary congested cymes.

Flower: Up to I cm long yellow fragrant , in axillary or

termind head like congested cymes, pedunc:les 8-15 cm

long,pubescent, stigma capitnte, unequally 2 lobed . Calyx

5- partite almost to the base, sepals long, broadly ovate or

su b-orbicular, obtuse, concave, ciliate, corolla la bes- 4 ,

ovate, acute, sub equal . Stamens exerted ovary and style

together reaching 0.6 cm long , the ovary tapering into and

about as long as the style , both villous , stigma shortly 2-

fid.

Fruit: A capsule, broadly ovoid , compressed , beaked ,

green almond shaped, densely silvery papillose. Seed

completely filling the fruit.

Flowering: June to September

Fruitins September to March

Re~eneration: The mature fruit falls 0x1 the ground, and

contains a well developed embryo inside. The seed

germinates within the fruit and the fruit contains the

seedling . A case of incipient vivipary . The embryo consists

of two fleshy, green conduplicate cotyledons , larger one

embracing the smaller .

Economic use: The leaves are useful as fodder , and

trunk us fuel. The wood could be used for house building

and boat making .

(Rhizop horaceae)

Occuxrence: Seen along the intertidal riverine banks. The

niche is confined to less salinity, soft mud and usually

found in the inland sheltered marshy areas and tidal

forests ( Fig.on Plate 11).

Growth form: A tree reaching to a height of 3-5, m with

dark brown bark and red close-grained wood.

Pneumatophores: Presence of geniculate roots which are

negatively geotropic helps in anchorage and exchange of

gases takes place through the pores or the lenticels

present on roots.

k a f : Opposite, coriaceous, entire, elliptic lant:eolate, acute

up to 10 cm long, 3 cm broad.

Inflorercence: Axillary cyme.

Flower: Calyx lobes recurved in fruit, petals short, obtuse,

slightly hairy.

Fruit: 1 -celled, I -seeaded, indehiscent , coriaceous ,

crowned with calyx lobes. -

Flowering: January- September

Fruiting: March- December.

Repeneration: Seedlings developed through the viviparous

hypocotyles. The relatively small fruit is readily dispersed

and establishes itself very quickly. I t is less shade tolerant

than Rhizophora and often observed as dense crop of

seedlings on cleared forest.

Economic use: The wood is used as fuel.

IV Excoecaria agallocha L.

Occurrence: An evergreen and apparently dec:iduous

sporadic tree, dioecious, common along the higher

estuarine banks, canals, creeks, tidal forests and

mangrove swamps. Prefers well drained heavy clay with a

little sand ( Fig. on Plate IV).

Growth form: Glabrouus trees orshrubs with an acrid

milky juice reaching to a height of 6m . Barks greyish

white, Smooth, lenticellate, woodsoft, light, taproot

insignificant.

Buttresses: Not buttressed, however sometimes flanging at

the base of the trunk is -observed. Taproot insignificant,

lateral roots spreading like snakes, intermingled each

other, superterranean roots produce elbo -shaped pegs of

knobs of pneumatophores with white lenticels. With this

type of root system the tree can tolerate the high tidal

effects.

Leaf: Alternate, thickly coriaceous, ellipt i r - ovate,

glabrous green shiny with a some what. crenulate margin

turn red before shedding. -

Inflorescence: Catkin like spikes.

Flower: Unisexual, fragrant, male flowers 2-3 mrn across

sessile, yellow in axillary many flowered catkin like spikes

3-7 cm long; female flowers 2.5-3.5 mm across pedicellate

axillary few flowered raceme, racemes 1-2.5 cm long.

Fruit: 1-1.5 cm across, depressed globose, 3 lobed

capsule, seeds subglobose -smooth, not carunculate, testa

crustaceous, albumen fleshy; cotyledons flat.

Flowering: February - August.

Fruiting: June- January.

Regeneration: In this species male and female flowers are

borne on separate plants. The seeds germinate to produce

seedlings. The mature fruits and seeds are deep brown to

black in calour.

Economic use: Woods are very light, much used for

packing box, may be utilised for good quality of paper.

V. Lumnitzera racemosa Willd.

Occurrence: Landward margin and also inner fringes of

the estuarine areas. If t h e mangrove swamps become

desalined this plant gradually estab1isht:d in such

habitatats. This tree grows in association with Rhizophora

mucronata along the salt water creeks and backwaters and

also common along the saridy and muddy flats under fresh

water regime ( Fig.on Plate IV).

Growth form: A large glabrous tree reaching to a height

of 4.5 M tall, outer bark dark brown longitudinally

fissured, live bark dark red, inner bark reddish brown,

becoming pale near the sapwood . Sapwood yellow brown,

heart wood dark brown.

Leaf: Alternate, sessile (petioles very short) coriaceous,

obovatc thick, entire ernarginate at apex, cuneate at base,

clustered towards the end of the branches; main nerves 3-

5 pairs indistinct. Hydathode at the apex of leaf.

Inflorescence: A terminal raceme.

Flower: 9-1 1 mm long, white sessile, in short axillary

spikes, receptacles 3-5 mm- long tubular with two adnate

persistant bracteoles, ovary oblong, elongated 4-5

capillary, unilocular ovoules pendulus from the top of

placenta, style subulate, stigma simple.

Fruit: 8- 10 x4-6 rnm, compressed, woody, ellipsoid, 1

seeded drupes, seeds elongated, pointed towards apex.

Longitudinally straight when dry, crowned by the

persistent calyx tube. Seed solitary, cotyledons convolute.

Flowering: January - March.

Fruiting: June December.

Regeneration: Through seeds.

Economic Use: Mainly used for fuel and also

occassionally as poles.

VI. Rhizophora mucronata Lamk.

Occurrence: Tree form, with gigantic growl h . Common

along the estuaries, riverine banks, creeks, canals and in

the mangrove swamps, trees can sustain higher degree of

tidal effects. Tidal forests on both coasts; more scarce than

the other Rhizophara species, common in the Krishna

Delta. A labrous small evergreen tree ( Fig.on Plate 11).

Growth Form: A gigantic tree from reaching up to a

height of 12m at some places.Usually facing the banks

and gets exposed to high tides. Pneumatophores are

absent.

Aerial Roots: Shows very interesting features(sti1t

roots)Aerid roots hangs out from the main tree and from

branches, this provides anchorage to the tree,and

exchange of gasses takes place through the lerlticels.

Leaf: Leaves elliptic,Iong-mucronate opposite,

coriaccous,glabrous,entire,stipules large.

Inflorescence: Axillary cymes.

Flower: 3-7 flowered on peduncles 2.5-:3.2crns long,

bracteoles connate at the base of the calyx.

Fruit: Corianceous, 1 -celled, 1 -seeded,ovoid, the persistent

re flexcd calyx- lobes surrounding its base . Hypocotyl

pendulous, germinating on the tree,elongate. Perforating

the apex of the fruit.

Flowering: August-December

Fruiting: Mid October- April

Regenexation: Germination of seedling from the long

hypocotyls. The length of the seedling as it detaches from

the parent plant is somewhat a handicap for dispersal by

water. Hence this species is restricted to the banks of

streams and never found more then a few meters distant.

Economic use: Useful as a tanning material, obtained

from the bark of the tree.Wood is dark red, very hard, used

as an excellent fuel.

MANGROVE ASSOCIATES( PRO ESTUARINE)

I. Cerebera odollam Gaertn.

( Apocyanaceae)

Occurrence: Occassionally in salt swamps and

backwaters. Dominates the inlands of the intertidal banks

where fresh water influence is high ( Fig.011 Plate VT) .

Growth form: A moderate sized tree, with rnilky latex -

poisonous juice, glabrous; branchlets whorled,

stout,marked with leaf scars.

Leaf: Alternate or scattered, long, lanceolate, leathery, - acute narrow at base, main nerves numerous, slender,

horizontal, connected by an intramarginal nerve; petioles

long.

Inflorescence: Terminal or pseudo terminal cymes,

Flower: Large; white yellow throat, fragrant, in terminal or

pseudo terminal cymes, calyx 5-lobed, eglarldular lobes

long, corolla large, tube cylindric below funnel shaped

above the throat with 5-villous scales; lobes 5, spreading,

overlapping to the left .Stamens small included; anthers

lancelet, apiculate, the cells rounded at base. Disk-0,

ova= of two distinct carpels, ovules 4 - in each carpel on

both sides of a thick placenta.

Fruit: A drupe, sub- globose, large 1.-seaded smooth,

green pericarp very thick, fibrous and woody seeds broad,

compressed, peltately attached to the enlarged placenta;

albumen none; cotyledons thin radicle very short.

Flowering: April - November.

Fruiting: September - March.

Regeneration: By seed.

Economic use: Bark and sap (milky latex) are used as a

purgative and for relief in rheumatism; a medicinal oil is

extracted from the seeds.

2. Acanthus ilicifolius Linn.

( Acanthaceae )

Occurrence: Common along the coasts in tidal swamps

and along the banks of creeks, estuarine islands and tidal

rivers. I t is often called the seeHolly. Somt: times found

gregarious along the banks of the fresh water rivers,

usually shows a capacity for tolerating various ecological

pitramcters ( Fig.on Plate VII).

Growth form: A perennial gregarious erect herb or shrub

up to 2 M height, with large blue opposite flowers and

simple spinous and holly-like leaves. Stems terate often

provided with aerial roots; leaves glabrous, possess two

sharp stipular spines in leaf axils and a pair of bracteoles

beneath each flower. Reclining stems develop aerial roots.

Leaf: Heteramorphic leaves, leaves with sinuate margin

and spine tipped lobes, and leaves entire and free from

spiny lobes. Opposite oblong or ovate, decursate or

lanceolate, coriaceous spiny narrowed at base, spiny at

apex, lateral nerves and midrib. Petioles short with two

stipule - like spines at the base.

Inflorescence: Simple or branched, spike 5.20 cm long

terminal.

Flower: 3.5 to 4 cm long, violet, pubescent within bracts

caducous at or before anthesis; bracteoles 3 to 4 mrn long

subtending the c:alyx.

Fruit: Capsules, ovary 2 celled, ovules 4, style slender

capsules oblong. Opening explosively to release the seeds.

Flowering: April - December.

Fruiting: July - February.

Regeneration: By reniforn seeds. Seeds 0.63 cm in

diameter, broadly ovoid or sub-,orbicular, much

compressed, testa very large. Germination hypogeal.

Economic use: Could be used as a hedge plant along the

landward margin of the mangrove habitat. In view of its

shrubby growth and close setting, the plant forms a good

fence. Leaf extract is used for relieving rheumatism and

neuralgia. fruit pulp is used as blood purifier and for

dressing boils.

3. Clerodendrum inerme Gaertn.

( Verbenaceae)

Occurrence: Common along the sea coast. Dominates

along the estuarine bank both in high and low salinity

levels ( Fig-on Plate V) .

Growth form: A strangling much branched shrub 1 to 3

M tall, sometimes scandent.

Leafi Opposite, entire, elliptic or obovate. c )btuse (rarely - ternatc) glabrous or nearly so, base acute; pt:tiolr:s 0.d -

1.9 cm long.

Inflorescence: Axillary pedunculate cymes.

Flowex: Peduncles long, slender, calyx cupular, teeth 5 ,

enlarged in fruit, corolla tubular, white, tube long hairy

inside, 5 -lobed, limb bilabiate, 1obr:s unequal

oblong. Stamens 4, . filaments exerted, red, didynamous,

anthers oblong, ovary imperfectly four celled, cells -

loculed, style long, stigma 2-fid.

Fruit: A large drupe, 4-lobed pyrene surrounded by striate

enlargc~d calyx.

Flowering: April - December.

Fruiting: October - February.

Regeneration: Seedlings are developed through the seeds,

easily propagated by cuttings, on saline and non saline.

Economic use: The juice of the leaves a]-(: ust:d as a

remedy to bring down fever. The plant could be used as

hedge plant while fencing.

4. Acrostichum aureum Linn.

Occurrence: Described as the "mangrove fern", occurs in

the back rnangal but seems particularly suited to

disturbed estuarine sites (some times inland in ,fresh-water

sites) .Terrestrial in brackish marsh( Fig.on Plate VI).

Growth form: Rhizomatous fern, Axis horizontal or erect,

irregularly branched.

Leaf: Frond very large, erect, simply pinnate with large

entire pinnae, thick coriaceous, glabrescent, venation

closely and uniformly reticulate without inclucicd veinlets .

Inflorescence: Sporangia borne in pir~nae of the distal

end or on distinct whole fronds.

Flower and Fruit: Densely covering the dorsal surface

with out distinction of sori, mixed with capitate lobed

paraphyses interpreted as abortive sporangia, large

annulus of 20 - 22 thickened cells, spores large, light

tetrahedral, minutely tuberculate.

Regeneration: Through rhizome

Economic Use: The fronds are used for thatching,

Pounded rhizome of Acrostichum aureum is used as a

medicine for wounds and boils; fronds are used a& antidote

for snake bite; litter for cattle.

5. Derrlo uliginosa Benth.

Occurrence: Fairly common climber along the coastal

es tuarics, intertidal riverine banks, muddy salt water

creeks and in mangrove swamps. Usually in association

with Rhizophal-a sp( Fig.on Plate V).

Growth form: In large climbing shrub, twining u n the trees

of Rhizophora.

Leaf: Imparipinnate, alternate, 1 0.4- 2 5 cm long; stipule

minute, leaflets 3-5, opposite, ovate, ovato-o blong and at

times oblong lanceolate, 4.5- 13 cm long, 2.5 - 6.4 cm

wide, glabrous, rigidly subcoriaceous, entire shortly

acuminate, apex obtuse, base rounded, exstipellate, lateral

nerves 8-9 pairs, leaf rachis and petiole grooved above,

glabrous petiole 3-4 rnm long, rarely 5 rnm long much

wrinkled.

Inflorescence: A raceme.

Flower: 1- 1.2 cm long, pink, bract minute, ovate,

bractioles present; pedicels slender, ' 2-3 mm long, not

fascicled pedicels and rachis glabrous. Calyx cup

truncate, teeth obscure, margin of the cup fringed with

minute hairs. Standard ovato -orbicular, lcm long, 0.9 cm

wide, kipex I-etuse, stamens 10, rnonadelphous, anthers

versatile. O v a y clothed with silky hairs, style long, stigma

minutely peltate, ovules 7-8.

Fruit: A pod obliquely rounded, rarely oblong, 2-5.2 crn

long, 2.5-3.8 crn wide, glabrous, winged on the upper

suture, reticulately veined, 1-2 seeded.

Flowering: June - December.

Fruiting: October - February.

Regeneratf on: Through seeds, seeds are ovato -orbicular,

reddish brown to black with radiating lines, 1.2 cm long,

1.5 cm wide.

Economic use: The stems are long wiry brached yield

strong fibre and are used as ropes. The seeds are used as

fish poison. Root powder is used as an insecticide.

6. Epaltes divaricata Cass.

Asteraceae (compositae)

Occurrence: All plains districts in dry country, in watery

places. ( Fig-on Plate X).

Growth form: Herbs, erect or diffuse

Leaf: Alternate, usually decurrent, toothed. Heads

heterogamous, small, disciform.

Flowers: Solitary or corymbose, the outer flowers female,

many-seriate, fertile, the inner male flowers usually sterile.

Involurce hemispheric or broadly campanulate ; bracts

many seriate, dry, rigid. Receptacle flat, or convex naked.

Corollas of female flowers tubular or funnel shaped, the

limb 3- 5 lobed. Anther bases sagittate, shortly tailed.

Style-arms of female flowers slender of male flowers entire

or bifid, papillose. Achenes of female flowers smooth.

Some of the male flowers of 2- 3 caducous hairs. Heads 2-

3 inch in diameter; involucral bracts longer than the

flowers; achenes obovoid ribbed and glandular.

7. Premna latifolia Roxb.

( Verbenaceae )

Occurrence: Near the coast in dry forest areas. ( Fig.on

Plate VII)

Growth form: Trees or shrubs, some times climbing

rarely, herbaceous under shrubs. Usually small tree

reaching 25 f t in height.

Leaf: Opposite or some times whorled, entire or toothed.

Leaves usually drying blue or black.

Inflorescence: Flowers in corymbose panicled, or thyrsoid

terminal cymes .

Flowers: Greenish white, bracts small, narrow, bracteoles

0, calyx small, campanulate, truncate 2-lipped or shortly

2-5 lobed somewhat enlarged in fruit. Corolla small, tube

short, often villous within; limb 2-lipped, 5 or

subset~uenily 4-lobed. Stamens 4, didynamous, inserted

below the throat of the corolla tube, ra~-ely exserted;

anthers ovate or rounded, the cells parallel or divergent.

Ovary 2 or 4 celled, 4 ovuled style linear, stigma shortly

bifid.

Fruit: A small drupe, seated on the calyx globose or

obovoid, mesocarp thin fleshy. Endocarp of 1 pyrene,

rugose or versulose, often with a central cavity. Seeds

oblong testa thin albumen, cotyledons flat.

8. Sida cordifolia Linn.

( Malvaceae )

Occurrence: A tropical weed. Generally distributed

through out tropical and subtropical India. ( Fig.on Plate

XI.

Growth form: Herbaceous, erect, cylindrical, branched,

solid puberulous, green. Annual or pernnial .

Leaf: Caulirle andrarnal, alternate, stipulate, cordate,

serratr:, acute, pubescent, unicostate reticulate.

Inflorescence: Solitary ,willary.

Flower: Yellow colour; Bracteate, pedicellnt.e, complete,

actinomorphic, hermaphrodite, pentamerous, h y p a ~ n o u s ,

and cyclic. Calyx - sepals 5, corolla, petals 5. Stamens

indefinite monoadelphous forming a staminal tube around

the style, epipetalous, anthers reniforrn, monotheous,

basifixed, extro se. Gynoecium- Multicarpellary ,

syncarpous, ovary multilocular, placentation axile, style

passing through the staminal tube, stigmas as many as

thecarpels and capitate.

Fruit: Schizocarp

Reveneration: Vegetative propagation.

Economic Importance: Leaves are applied to inflammed

sores rmd wounds for cooling and healing. 1)ecoction is

given in dysentry.

9. Ipomaea pes - caprae L.

( Convolvalaceae)

Occurrence: Ipomaea pes-caprae is planted on the Indian

coast to bind the sand and aIso grown as an ornamental

plant. Occur in all parts of the world except the coldest,

and is especially numerous in tropical Asia. ( Fig-on Plate

1X) .

Growth form: A large creeping or climbing plant; erect or

prostrate herb annual or perennial from a tough woody

rhizome by means of which under desert conditions, the

plant is enabled to persist from season to season.

Leaf: There is great diversity in form of leaves which are

generally stalked and without exception exstipulate.

Scale-leaves are absent from the aerial shoot. The buds on

subterranean shoots are protected by scale leaves. The

leaf margin is entire, often with a hastate or cordate base.

Flower: Solitary in the leaf- axils, with the two bracteoles

scale-like and at some distance below the flower.

Regularly pentamerous with reduction to two in the

woecium. Corolla is generally funnel shaped, with entire

or slightly lobed margin. Flower large and generally

brightly coloured with violet corollas visited by insects for

nectar excreted on the hypagynous disc. Flower remain

open for one day only after which the edges of corolla roll

up inwards, closing the tube with the ovary.

Inflorescence: Capitate (through suppression of the

stalks)

Fruit: Four or six valved capsule. Testa is generally

smooth but some times warty or hairy.

Economic uses: Plant used as sand binder, also used as

a hedge plant.

9. Thespesia populnea Soland ex-corr

( Malvaceae J

Occurrence: Small to medium sized trees, found

throughout the plains and also distributed i n the tropics

mainly on the coasts. ( Fig.on Plate X).

Growth form: Medium sized trees up to 8 M tall,

branches scabrous. Quick growing evergreen tree with

dense foliage and spreading branches, whir: h rnake it

eminently suitable as a shade tree.

Leaf: Leaves green deeply cordate; pedicels erect; one to - five cm long with a bracteate joint very near the base,

entire.

Flower: Solitary, axillary of distal foliage leaves, colour of

flower changes from yellow to purple within 21 hours;

calyx is cupular and either entire or at most with a series

(5) of short teeth.

Fruit: - Fruit becomes dry and normally remains

undehisced on the tree, or at most with the wall rupturing

irregultirly .

Flowerlnp and Fruiting: Through out year.

Regeneration: Through stem cuttings; fruit itself floats

which floats is the primary organ of dispersal, ~ilthough the

seeds themselves also float when released by shattering or

decay of the capsule.

10, Calophyllum inophyllum Linn.

Local name: Punna

Occurrence: I t is essentially a littoral tree of the tropics

occurring above the high tide mark along the sea coast of $

the Indian peninsula. ( Fig.on Platc IX)

Growth form: A middle sized, glabrous ,evergreen tree;

leaves elliptic -1anceolate , obovate , nerves numerous

,parallel, very fine, conspicuous below ; flowers scented , in

axillary recemes , ovary usually bright pink; drupe

globose.

Flowerinn and fruiting: March to June

Ecological notes: I t generally grows on the detritus

brought dawn by rivers and on the sand and singles

banked up by the wind and waves , and act as an efficient

shore protector in most places.

Importance and uses: The tree yields a resinous gum and

an oil is extracted from the seeds. Its timber is used for

masts, railway sleepers and various purposes in ship

building. The tree is planted as avenue trees.

11. Crotalaria sericeae Retz.

( Papiloneaceae)

Growth form: A robust under' shrub 3-4 feet: high, with

stout a triated branches.

Leaf: Oblanceolate-oblong , moderately firm in texture, 3-6 - inches , cuneate at the base,stipules leafy persistent ,

glabrous above finely silky beneath.

Inflorescence: Recemes ,

Flower: 20-40 flowered often a foot long ,bracts persistent

,refiexed , pedicels exceeding calyx. Calyx Y d inch , teeth

lanceolate , twice campanulate tube. Corolla half as long

again as cdlyx, generally purplish.

Fruit : Pod 1-2 inch long ,distinctly stalked .

12. Crotalaria striata DC.

( Papiloneaceae)

Growth form: An erect low shrub 2-4 feet high with robust

sulcate thinly silky branches. ( Fig.on Plate VIII).

Leaf: Leaflets obovate - oblong obtuse or sub-acute.

Leaflets membranous 3-4 inch long, usually green and

glabrous above, pale and obscurely silky below.

Inflorescence: acemes terminal and lateral elongated.

Flower: 20-50 flowered, reaching '/a - lfeet long. Calyx '/4

inch long thinly silky. Teeth lanceolate as long as the tube

Corolla glabrous yellow striped with red .

Fruit: Pods deflexed, rather re-curved 1 Y2 -2 inch long, 20-

30 seeded.

13, Fimbristylh ferruginea Vahl,

( Cyperaceae )

Local name: Eera.

arowth form: FIerbs,usually erect , with a short I-hizorne

or fibrous roots, rarely stoloniferous . Stems usually tufted

( Fig.on Plate 1x1.

Leaf: Leaves narrow , from near the base of the stem,

sometimes all reduced to sheaths .

Inflorescence: Terminal ,umbellate, corymbosr: or reduced

to a few spikelets or a single one. Spiklets solitary or

clustured usually many flowered , the solitary usually

pedicilled but frequently one or more in the corymb sessile

Flower: Glumes ferruginous -brown , hoary- puberulous

outside in the apical half ,glabrous and usually paler in the

basal half, broadly elliptic - ovate , apiculate , concave ,15

-17 inch long keel green .

Fruit: Nut broadly obovoid , umbonate, shortly stalked,

smooth pale yellow .

14, Pennisetum polystachyon Sc h,

( Poaceae J

Local name: Kampam

Growth form: Annual or perennial , erect ,often tall

,simple or branched herbs . Fig.on Plate IX)

Leaf: Narrow flat or convolute.

Inflorescence: Panicles spiciform ,usually dense ,

branches numerous, short and simple wit11 a solitary

spikelet or scantily divided and the spikelets in clusters of

2-5. Inner bristles laxly ciliate,longest upto 0.5 inch long

;spikelets sessile.

Flower: Lower glume minute or suppressed , puberulous .

Fmit: Grain narrowly oblong to orbicular ,enclosed in the

slightly hardened lemma and palea .

15. Mariscus javanicus(Houtt)Merr.et MetCalf

( Cyperaceae )

Occurrence: Common in aquatic habitats along brackish

river and lake banks and sea coasts. ( Fig.on Plate VIII)

Growth form: Erect herbs , usually perenniaf and

glabrous ; resembling the genus cyperizs . Rhizome short

and thick. Culms tufted and robust , upto 1 m or even

taller and 5 mrn wide , obtusely trigonous and smooth .

Leaves: Basal, many much exceeding culm lower ones

reduced to sheaths and upper bladed; lower sheaths

coriaceous , up to 6 m long, purplish -striate,sub

acute, t hinly membranous on margins , upper thickly

coriaccous and some what spongy.

Inflorescence: Compound to decompound umbel , 20 x

15 cm ; bracts up to 8 , leaf like ,lower ones much

exceeding umbel . Spikelets congested , horizontal to

shortly reflexed, lanceolate to elliptic - lanceolate .

Flower : Fertile glumes coriaceous, closely imbricating ,

broadly ovate ,keeled on midrib, pale brown to brown and

purplish - lineolate between nerves.

Fruit: Nut obovoid to ellipsoid , dark brown to black

minutely punctulate

Flowering and fruiting: September to March

16. Agyneia bacciformis A.

Occurrence: East coast , in grassy pastures near the sea .

( Fig.on Plate VIII)

Growth form: A n annual or biennial herb with sraggling

branches Stems often angular or compressed .

LeafiLeaves small ,&ernate ,entire , stipules acuminate .

Flower: Minute , monoecious , male in axillary cluster ,

female large solitary ; bracts numerous, stipule like .

Fruit: A capsule , splitting in to 3-2 valved cor:ci.

Seeds: 6 slender ,curved , with an elor~gated hilum.

Albumen fleshy,embryo curved the cotyledons flat

5.5, Discussion

Mangroves in Ayiramthengu were seen on sancly, silty and

clayey muds or mixtures of these. Often they for-m soft

muddy substrates under the influence of' tidal range

where mud was deposited naturaly. Under tht: canopy of

mangrovephytes the substrate undergo physico-chemical

alternation which determine the formation of zones within

the habitat.

Mangrove forests became centres of interest for- many

biologists in the last century. In part this interest was due

to the unique form of the aerial roots of :% rrlangrovc tree.

As the mangroves grow in the anaerobic soil, the rooting

systems of these mangrove flora exhibit in this harsh, salty

environmental situation. Pervical & Worncrslcy ( 19 7 5) and

Gill 86 Tomlinson (1975-1977) have described those

different types of rooting patterns among these mangroves.

Those are pneumatophores, stilt roots, knee roots and

buttress roots.

Ecologically, the mangrove forests represent zi rather sharp

transitional gradient between the marine and the

freshwater environments. Each biota or group of biota

occupies a niche and even forms an aggregate and spatial

zonation of its own. Mangrove seedlings require low

salinity; their salt requirements increase with growth. In

general mangrove vegetation tends to be more luxuriant at

lower salinities (Kathiresan et al., 1996b). In Ayiramthengu

mangroves generally salinity value was less it ranged

between 6.28 Yoand 0.34%. Also after monsoon, low

salinity and high nutrient concentrations produce

luxurient growth of rnangroes. Similar observation was

shown by Pichavaram mangroves (Kathiresan et al.,

1994b).

The major propotion of the Ayiramthengu mangroves are

shrubs with the average height of 2 to 4 meter based on

the classification of Champion and Seth (1968).

Ayiramthengu mangroves can be viewed as fringe

mangroves on the shoreline, patchy mangroves along the

tidal rivers and creeks, and an inland mangrove pocket of

Kayamkulam Kayal. The tree heights of Avicennia vary

from 2 m to 8 m. The flowering season of the mangroves,

especially Avicennia officinalis starts during June and the

fruits mature during August and the fruit fall coincides

with the monsoon as it was recorded in, th.e east coast

mangroves of Pichavararn and Muthupet (0 swin, 1997).

Present study also agrees. with the above finding. These

areas are unique by the regular tidal flushing with high

rates of organic exchange. Avicennia o fficinalis, Rhizop hora

rnucronata, Aegiceros comiculatum occur in this type of

forests.

In addition to species composition one can

differentiate various zones. These zones are governed by

the interaction of factors such as the frequency and length

of time of submergence, -the salinity and the drainage

system. Generally each zone is called by the dominant

woody tree species, for example there can sometimes be

distinguished (from outer edge to the inner zone): an

Avicennia zone, a Rhizophora zone, a Bruguiera zone etc.

Present study agrees with observations made by Ananda

Rao e t al,, (2000) in Karnataka mangroves.

I t has been noticed that the salinity of the water

determines the composition of the mangrove vegetation. A

relatively stable fringing forest stage was r:s tablished in

Ayirarnthengu. The following associes / associations

recognised in the course of this study:

(a)Rhizophora mucronata consocies : The area is a

narrow strip parallel to flowing river or to lagoon banks.

Rhizophora mucronata grows up to 25 m, height with

multiple branches spreading over the area and produces

elaborate net work of interlocking stilt roots.

(b)Rhizophora-Bruguiera gssociation : With the process

of reduced accretion due to occasional inundation with

above average high tides there is a change in the flora into

Rhizophora - Bruguiera association. The individual trees

are straight and attain a good height and show dense

crown of leaves on the branches, Bruguiera, being a shade

tolerant, grows quite well between and below the crown

shadow of Rhizophora. On slightly higher relief, the fern

Acrostichum aureum, the shrub by Acanthus ilicifolius and

Clerod end ru rn inenne occur sporadically.

(c ) Adcennia offlctnalis consocies : On the banks of

station 11, where clay soil was present, Avicerznia o fficinalis

is found in abundance.

(d)Aegiceras - Excoecda association: This association

is very common towards the landward margin of the

estuarine banks. Low lying island reliefs are often covered

with Acanthus ilicifolius formation almost to the exclusion

of other mangrove taxa. The only climber on the mangrove

taxa lining the tidal river banks was Derris.

(el Acrostichum - Acanthus association : The chief

component of the secondary formation is that of

Acrostichum aureum often mixed up with Acanthus

ilicifolius or Clerodendrum inerme.

The above observation agrees with those made by Ananda

Rao on (2000) about Karnataka mangroves.