Floral Composition and Taxonomy of Mangroves of Andaman and Nicobar Islands

IndianIndian Journal Journal of ofGeo-Marine Marine SciencesSciences Vol. 43(6), June 2014, pp. 1037-10501031-1044

Floral composition and taxonomy of mangroves of Andaman and Nicobar Islands

Ragavan, P'", Mani Saxena', Alok Saxena', Mohan, P.M.I, Sachithanandam, VI.4 & Tarun Coornar'

"Department of Ocean Studies and Marine Biology, Pondicherry University, Brookshabad campus, Post Bag No.26, Andaman and Nicobar Islands, Port Blair-744 112, India

2 Indira Gandhi National Forest Academy, Dehradun-India 3-Andaman and Nicobar Island Forest plantation and Development Corporation Limited, Vanvikas Bhavan, Andaman and Nicobar Islands, Port Blair-744 102, India

4_, National Centre for Sustainable Coastal Management (NCSCM), Ministry of Environment and Forest (MoEF), Government of India, Koodal Building, Anna University Campus, Chennai-600 025, India [E-mail: [email protected]]

Received 17 December 2012,' revised 3 May 2014

Actual number of mangrove species found in the Andaman and Nicobar Islands outnumber the number of species recorded to occur there. Present srudy consists reviewing the literature on mangrove floral composition and distribution as well as highlighting the causes of such apparently large species numbers and apparently incorrect identification of some of the mangrove species in the Andaman and Nicobar islands. Mangrove survey indicates that there are 33 exclusive 'mangrove species', at least 27 'mangrove associates' that occur on the islands.

[Keywords: Andaman and Nicobar Islands, Mangroves, Floral composition, Taxonomy]

Introduction Species composition of mangroves is a basic and important prerequisite to understanding all the aspects Mangrove forests are among the world's most of structure and function of mangroves, as well as productive ecosystems, situated at the interface their bio geographical affinities and their conservation between land and sea in the tropical and subtropical and management-". latitudes 1,2. Despite its ecological and economical values, globally mangrove areas are disappearing at Andaman and Nicobar islands (ANI) are located the rate of approximately 1% per year'". However, in the Bay of Bengal, off the eastern coast of India, there is very little known about the effects of either between 6°N to 14ON latitude and 92° E to 94°E widespread or localized mangrove area loss on longitude and bestowed with dense mangrove cover", individual mangrove species or populations due to Approximately 89% ofthe mangrove cover falls under the lack of species specific informations. Though 39 the category of either very dense mangrove (with more true mangrove species known to occur in India, the than 70% canopy density) or moderately dense actual number of mangrove flora that exists in mangrove (with canopy density between 40% and different regions of India is not fully known due to 70%). Mangroves in these islands mostly fringe the scattered data, the absences of their comprehensive creeks, backwater and muddy shores. According to compilation and lack of extensive field survey". the latest estimate of the Forest Survey of India", the

*Corresponding author. 10381032 INDIAN J MAR SCI VOL. 43(6), JUNE 2014 total area under mangrove cover in India is 4663 km2, 617 km2 of which (13% of the total mangrove area of the Indian Territory) occurs in the ANI9. In Andaman district, the area under mangroves is 614 km2, while in Nicobar district mangroves occupy only 3 km2 reported by FSI9. The area under mangrove cover in has decreased significantly during the last decade FSI 9,10 possibly leading to change in floristic composition and local extinction of some species. According to FSI10 about 43 km2 of mangrove cover decreased between 2003 and 2007 in the ANI. Figure 1 Acanthus species; (a-b) A. ebracteatus (a) White Only few field based studies had been carried out colour flowers (b) fruits (c-j) A. ilicifolius (c)Flowering spike (d) Violet colour petals of A.illicifolius (e) Fruits (f) spine less on floral composition of mangroves of ANI. In earlier narrow leaves A.illcifolius (g) spine less leaves and spines at references such as Kloss11 and Parkinson12 mangrove nodes (h) spine less leaves and absences of spines at nodes species were reported in their work on forest flora of (i)Spine less broad leaves of A.illicifolius (j) Fruits of Andaman’s. Afterwards Sahni13 and Blasco14 have A.illcifolius with unarmed stem and leaves (k-n) Acanthus volubilis (k) White colour flowers (l) Flower spike with 15 reported 28 mangrove species. Mall et al. reported unarmed stem and leaves (m) Fruits (n) leaves of A.volubilis 26 exclusive mangrove species. Dagar et al.16, have with salt crystals. reported total of 34 exclusive mangrove species among 17 genera and 13 families. Later Singh17 photographic evidence also collected for all the reported 28 excusive mangrove species. More recently species. All mangroves species encountered during Debnath18 and Mandal and Naskar19, observed 59, and the field survey were identified based on their key 61 species from ANI, including some salt marsh and characters. All sites were visited four times in a year associated plants. Singh and Garge20 reported 27 to record the floral composition. Figure 1 and exclusive mangrove species. Present study aims to Appendix 1 shows the location of surveyed sites of provide an up-to-date list of the floral composition ANI in this study. of mangrove of the ANI. Results and Discussion Materials and Methods It is observd that 33 true mangrove species and During 2009-2011, field surveys were carried out 27 mangrove associates in this study. Most on six islands namely South Andaman, Havelock, controversial species among researchers are Middle Andaman, North Andaman (Mayabunder and Acrostichum sp, Acanthus sp, Pemphis acidula, Diglipur), Little Andaman and Car Nicobar (Fig. 1). Phoenix paludosa, Cynometra sp and Dolichandrone On each Island a minimum of two sites (mangrove spathacea. a as mangrove associate species and creeks) was selected and a total of 25 sites surveyed. Acrostichum sp and Pemphis acidula as minor In each site minimum 10 quadrates (10 m X10 m) element. Duke30 included all the above mentioned were laid randomly in order to cover all the zones of species as a mangrove species except Acanthus the mangroves. All vascular plants and ferns volubilis. Kathiresan and Bingam1 considered encountered during the survey were identified in the Cynometra sp, Dolichandrone spathacea and field using Duke and Bunt21, Tomlinson22, Duke and Pemphis acidula as mangrove species and Jackes23, Banerjee et al.24, Duke25,26, Kathiresan27, Acrostichum sp, Acanthus sp, Phoenix paludosa are Kathiresan28, Debnath18, Dagar et al16, and Giesen et not considered as mangroves. Giesen et al.29, al.29 Herbarium is prepared for all encountered true classified Acrostichum sp and Acanthus sp and mangrove species and deposited in Botanical survey Pemphis acidula as true mangrove species and of India (BSI), Regional centre at Port Blair, Phoenix paludosa and cynometra sp as mangrove RAGAVAN et al: FLORAL COMPOSITION AND TAXONOMY OF MANGROVES 10391033 associate. Among the Indian researches Dagar et al.16, did not report aforementioned mangrove species in Singh17 and Dam Roy et al.31, classified Acanthus sp, 2003. Contemporary to this study, Dam Roy et al.31, Cynometra sp and Phoenix paludosa as mangrove in 2009 reported 25 true mangrove species with some species and Acrostichum sp, Pemphis acidula and uncommon mangrove associates. He also did not Dolichandrone spathacea are considered as mangrove report above mentioned species except Bruguiera associates. While Debnath18 classified Acrostichum sexangula. Although Dam Roy et al.31 provided the sp, Phoenix paludosa and Dolichandrone spathacea as obligate mangroves (true mangroves) and Acanthus sp, Cynometra sp and Pemphis acidula as facultative mangrove species, Mandal and Naskar19 included all the above mentioned controversial species in his list except Acrostichum speciosum and Pemphis acidula, but he has not classified the mangrove as true and associates. Recently based on leaf trait and salt content Wang et al.32, classified that Acrostichum sp, Heritiera littoralis and Excoecaria agallocha as mangrove associates and Xylocarpus granatum, Acanthus sp. and Pemphis acidula as true mangrove species. Figure 2 Avicennia species: (a) Rounded leaf tip of A.officinalis (b) Long beaked capsule like fruits of Though the uncertainty still persist, present study, A.officinalis (c) Acute leaf tip of A.marina (d) Short beaked included Acanthus sp, Acrostichum sp., Cynometra capsule like fruits of A.marina (e-h) Variant of A.marina (e) sp., Dolichandrone spathacea, Pemphis acidula and Shrub in nature (f) Cluster of flowers in three branched heads Phoenix paludosa as exclusive mangrove species by (g) capsule like fruits with slightly curved short beak (h) strongly recurved calyx lobes) (i-m) Variant of A.marina with 22 16 25 reconciling Tomlinson , Dagar et al , Duke , lanceolate like leaf (i) Upper surface of the leaf (j) Lower Kathiresan and Bingham1 and Debnath18 and based slivery gray color of the leaf (k&m) fruits without conspicuous on the abundances and occurrence within the beak (l) flowers. mangroves areas of ANI. List of true mangroves identification guide for 25 true mangrove species, he species reported by various authors in ANI are given appears to have misidentified Acanthus illicifolius as in Table 1. Appendix 2 provides details of the Acanthus volubilis, Barringtonia racemosa as locations of each true mangrove species recorded in Barringtonia asiatica, Finlaysonia obovata as ANI. Sarcolobus carinatus, Stenochlaena palustris as During the survey we could not encounter seven Acrostichum speciosum and illustration of Bruguiera previously reported species namely Aegialitis sexangula similar to variations of Bruguiera rotundifolia, Aglaia cucullata, Ceriops decandra, gymnorhiza. Present study described the key Kandelia candel, Bruguiera sexangula, Cynometra diagnostic characters of each species and interesting ramiflora and Sonneratia apetala. However we found morphological variations among the individuals of wide variety of morphological variations of its similar the same species, as follows. species and this suggests that these species might have Acanthus been misidentified by earlier work or authors16, 18. Moreover, the wide variation within the same species Genus Acanthus (Fig. 2) has three distinct is indication of increasing environmental stresses and mangrove species i.e. Acanthus Acanthus ilicifolius epigenetic changes among the population of the same L., Acanthus ebracteatusVahl and Acanthus volubilis species33. So there is likelihood that some of these Wall. All the three species were previously reported species might have become extinct from this region. from ANI. However, the existence of A. volubilis is Singh et al.34 noted that some of the above mentioned considered as doubtful in ANI by previous species are endangered and vulnerable. Singh17 also researchers15-17 because A. volubilis is not recorded 10341040 INDIAN J MAR SCI VOL. 43(6), JUNE 2014 further after the first record by Parkinson12 and Thothathri35. Moreover there was dispute on identification of A.ilicifolius and A.ebracreatus among the Indian researchers6. But in this study we located all three species. A.illicifolious is very common and easily differentiated from A. ebracteatus by its violet or purple coloured flowers. Most interestingly we have noticed marked differences in serration of leaves among the population of A. ilicifolius, in many sites it possess spineless leaves Figure 3 Small flowered Bruguiera species (a-d) B. cylindrica (a) Slightly curved propagules (b&c) Three flowered and shape of the leaves varies from needle like to inflorescence (d) Dark green folded leaves ( e-h) B. parviflora broad acute and spines at the nodal region is either (e) Pencil like propagules (f) Inflorescences (g) Yellowish present or absent . This observation insists that there green leaves (h) Persistent calyx tube with propagules must be a warrant varietal species among the to stigma and the presence and absence of beak in population of A.ilicifolius. A. ebracteatus, is located fruits among the individuals of A.marina. According in two sites i.e sippighat and shoal bay (South to Duke25 the above mentioned characters are key Andaman), has white flowers which turn to brown feature for the differentiation of Avicennia species. when it’s mature. Important characters by means of Some of the A. marina exhibit small flower, narrow which we used to distinguish A.ilifolius and elliptic leaves and stigma positioned below lower edge A.ebrcateatus is inflorescences and position of spine of anthers and beaked fruits like A. alba with capitate at nodal region. Inflorescence is terminal in A. inflorescences. But A. alba possess spicate ebracteatus and A.ilifolius exhibits both axial and inflorescences unique within the genus (other terminal inflorescences. Spines at nodes are facing Avicennia species possess capitate inflorescences). So downward in A.ebracteatus and upward in it is appears that ecological variants of A. marina A.ilicifolius. Another distinguishing character is might have been misidentified as A. alba by Mandal bracteoles, which is persistent in A. ilicifolius and 19 19 inconspicuous in A. ebracteatus. Acanthus volubilis and Naskar . Moreover except, Mandal and Naskar is easily identified by its unarmed and twine nature no records are available for the presence of A. alba in and white color flowers. We located A. volubilis only ANI. The key diagnostic features to distinguish A. in shoal bay and its occurrence in ANI is confirmed. officinalis from A. marina are the rounded leaf tips Although Dam Roy et al.31 identified A.volubilis from and large flower. Generally A. marina exhibit leaves ANI the illustration resembles the A .illicifolius with with acute tip with small flowers. In addition to that spine less broad leaves with acute tip and without A. officinalis is distinguished from A. marina by its spines at nodal region. propagules with slightly curved beak whereas A. marina exhibit very short beak and style length is Avicennia relatively longer that A. marina and radicle is Two species of the genus Avicennia (Fig. 3) i.e. glabrous in A. marina whereas hairy in A. officinalis. Avicennia marina (Forsk.)Vierh and Avicennia Bruguiera officinalis L. were known to Occur in ANI16&18 and the occurrence of Avicennia alba Bl. in ANI is Bruguiera (Fig. 4,5,6) is the largest genus in the uncertain because only Mandal and Naskar18 in their Rhizophoraceae22,36-39.With the exception of review work included A. alba in the floral list. We Bruguiera exaristata Ding Hou and Bruguiera also not encountered A. alba but we found variation hainessii C.G.Rogers the remaining four Bruguiera within the population of A. marina. Particularly in species i.e Bruguiera gymnorrhiza (L.) Savigny, Junglighat area we have noticed marked differences Bruguiera parviflora (Roxb.)W.A. ex Griff., Bruguiera in leave size and shape, position of anthers in relation cylindrica (L.)Bl.and Bruguiera sexangula RAGAVAN et al: FLORAL COMPOSITION AND TAXONOMY OF MANGROVES 10351041

Figure 6 Ceriops species (a-d) C. tagal (a) Glossy green leaves (b) Hanging down propagules (c) Inflorescences with long peduncle (d) upward facing calyx lobes (e-h) C. decandra (e) leaves (f) upright propagules (g) Inflorescences with short peduncle (h) downward facing calyx lobes

(Lour.)Poir were recorded from ANI16,18-19. B.cylindrica and B.parviflora possess small and erect flowers whereas B. gymnorhiza and B. sexangula possess large, recurved flowers22,40. In earlier 15 Figure 4 Variation in Calyx color of B. gymnorhiza (a) references of Mall et al. B. cylindrica is mentioned reddish (b) yellow and Rose (c) Shady white (d) greenish red as rare species in ANI but in this survey we have e) green (f) pale red (g & h) Mature and young propagules recorded this in most of the sites. The Key character with green calyx tube and green color petiole (i & j) Mature of B. cylindrica is in three flowered inflorescences and young propagules with reddish calyx tube and reddish petiole (k) Propagules with yellowish orange calyx tube and and dark green leaves, folded when mature. B. yellowish green petiole parviflora is distinguished by its small yellowish green leaves and pencil like propagules with persistent calyx tube and its common in ANI (Fig. 4). In ANI information about Bruguiera sexangula is very limited due to the lack of detailed taxonomical survey. B. sexangula from ANI was reported by Singh et al.41 and no further collections are available18. Mall et al.15 and Singh and Garge20 also mentioned that only few number of B. sexangula was observed only from Brumanallah area in south Andaman. Moreover, the records of B. sexangula from ANI by previous authors appear to be doubtful as they followed the calyx color as key character to distinguish B. sexangula and B. gymnorhiza. In addition Dagar et al.16 mentioned that calyx colour of B. sexangula is initially green and turns to yellow when mature. According to Duke26 the presence and absence of petal spine and number of petal bristles at the apex of the petal lobe are the key characters to distinguish Bruguiera species. Generally in B. sexangula petal Figure 5 Variation in length of petal spine and number of spine is shorter than the petal lobe and petal bristles petal bristles of B. gymnorhiza (a) Petal spine equal to petal are absent or minute26. In the present study we could lobe (b) Petal spine shorter than the petal lobe (c) Petal spine greater than the petal lobe (d) petal with two bristles (e) petal not identify B. sexangula based on the number of petal with three (f) petal with two bristles and one small stub. bristles and petal spine, rather we found wide variation 1036 INDIAN J MAR SCI VOL. 43(6), JUNE 2014 1042 in calyx color, number of petal bristles and length of petal spine among the individual specimens of B. gymnorhiza. We have observed different colors of calyx tubes of B. gymnorhiza like reddish, greenish orange, yellowish, orange, pale green and shady white (Fig-5). Calyx with yellowish colour is key character of B. sexangula, whereas pale green is calyx colour of B. hainesii. But the all the flowers exhibit petal bristles with 2-3 mm long, characteristic of B. gymnorhiza. We also observed this color variation in matured propagules with persistent calyx tubes (Fig. 5). Petiole color also varies like green, reddish Figure 7 Sonneratia species (a-c) S. alba (a) Flower with and yellowish green (Fig. 5). According to Duke26 white stamens (b) Fruit with clayx lobes bent back towards the stalk (c) Drop shaped leaves (d-f) S. caseolaris (d) Flower petal spine of B. gymnorhiza is shorter than the petal with red colour stamens (e) Fruit with flattened apex (f) leaves lobe, petal bristles are three in number and greater (g-i) S. ovata (j) Flower (k) Fruits with enveloped calyx (l) than 2mm long but we have observed three groups of Rounded leaves (j-m)S. griffthii (j)Blanchet with flowers and B. gymnorhiza based of the length of petal spine i.e. obovate leaves (k) Flower with white stamens and petals are absent (l) Fruit fattened at apex (m) Fruits with short style petal spine equal to petal lobe, petal spine shorter than the petal lobe and petal spine greater than the petal tagal without flowering and fruiting it is understood lobe (Fig.6). Although this observation shows that C. tagal might have been misidentified by unreliability of petal spine and bristles as key to previous authors16,18. So the occurrence of C. decandra identification of Bruguiera species, Sheue et al.42 in ANI is still doubtful. Mall et al.15, Singh17 and Dam illustrate that the petals of B. gymnorhiza with petal Roy et al.31 also did not report C. decandra. spine greater than the petal lobe and the petal bristles Sonneratia vary from 2-3. This indicates that there could be two forms of B. gymnorhiza. These observations may infer Earlier four species of genus Sonneratia (Fig. 8) that B. sexangula might be misidentified or extinct in i.e. Sonneratia apetala Buch.-Ham, Sonneratia alba ANI if previous authors’ reports are considered to be correct. Singh et al.34 also described that B. sexangula is endangered in ANI. Ceriops Two species of genus Ceriops (Fig. 7) namely Ceriops tagal (Perr.) C.B. Rob. and Ceriops decandra (Griff.) DingHou have been reported from Andaman and Nicobar Islands16,18. We, however, could not encounter C. decandra in this survey. Previous authors also mentioned that C. decandra is rare species16. C. decandra is easily distinguished from C. tagal by its short peduncle, calyx lobe facing downwards, sharply ridged short hypocotyl warty towards apex and hypocotyls always in upright position. C. tagal possesses long peduncle, long propagules with yellow color collar and calyx lobes facing upwards. C. tagal Figure 8 Lumnitzera species (a &b) L. racemosa (a) succulent is most common in Andaman group of islands. As it spatula-like leaves with an apical notch (b) white color is very difficult to distinguish C. decandra from C. flowers of (c-d) L. littorea (c) Red colour fowers (d) leaves. RAGAVAN et al: FLORAL COMPOSITION AND TAXONOMY OF MANGROVES 10431037

J. Smith, Sonneratia caseolaris (L.) Engl. and Sonneratia globally threatened species43. In this study we griffithii (Kurz.) have been reported from ANI16, 19. In recorded this species in three sites Mohanpur, the present survey we have identified four species namely Dhaninallah creek and Parangara creek (North S. alba, S. caseolaris, S. griffithii and S. ovata. We did Andaman). S. caseolaris was recorded only in V.K not encounter S. apetala which is easily differentiated Pur Creek in Little Andaman. from other Sonneratia species by its narrowly elliptic Lumnitzera leaves, apetalous flowers, calyx with four lobes and large umbrella shaped stigma. Similarly Debnath18 and Dam Within the genus Lumnitzera (Fig. 9), Ray et al.31, did not recorded this species, though it was Lumnitzera littorea (Jack.)Voigt. is most common reported by certain previous authors like Dagar et al.16 in South and Middle Andaman and easily and Singh17. So the existence of S. apetala in ANI needed identified by its red colored flowers. Lumnitzera to be confirmed whether it is extinct or misidentified by racemosa Willd is common in Mayabunder, previous authors. S. caseolaris is easily differentiated Diglipur (North Andaman) and Car Nicobar by its reddish stamens whereas S. alba, S. griffithii and (Kimous bay) and indentified by its white colored S. ovata have white stamens. S. ovata is distinguished flowers. L. rosea, a putative hybrid between L. from S. alba and S. griffithii by its enveloped calyx and littorea and L. racemosa, was not encountered almost round leaves. Although Dam Roy et al.31 reported during the survey although both the parents occur S. ovata as a new record from ANI, he found that species together in many sites. L. rosea exhibits rose only in Havelock islands but in this study we observed colored flowers. S. ovata in four sites i.e Havelock, Indira nagar, Wandoor Rhizophora and Shoal bay in South Andaman. S. alba is easily Genus Rhizophora is common in the Indo- identified by its broadly drop-shaped leaves and West Pacific region. Among the five Rhizophora persistent sepals whose tips bend back towards the stalk species in this region, four species (Fig. 10,11,12) (refluxed). S. alba is most common in ANI. S. griffithii namely, Rhizophora apiculata Bl., Rhizophora can be distinguished from other species by its obovate mucronata Poir., Rhizophora stylosa Griff and leaves, absences of petals and larger globose fruits Rhizophora lamarckii Montr, have been reported flattened or depressed at apex. S. griffithii is one of the from ANI16, 18-19, 41. Genus Rhizophora is easily differentiated from other mangrove species by its

Figure 9 Rhizophora species ( a-d) R. apiculata (a) acute narrow leaves (b) two flowered inflorescences with short peduncle and Figure 10 (a-d) Variation in leaf color of Rhizophora sp corky brown bract (c) flower with stamens (d) style (e-h) R. (a) Dark green broad leaves of R. mucronata (b) mucronata (e) Yellowish green broad leaves (f) inflorescences yellowish green broad leaves of R. mucronata (c) Dark with long peduncle (g) Hairy white petal (h) style (i -l) R. stylosa green leaves of R. stylosa ( d) Light green small sized (i) Dark green slightly broad and acute leaves (j) Inflorescences leaves of R. stylosa (e-i) propagules of Rhizophora sp (e) ( k) Hairy white petals (l) longer Style. R. mucronata (f& g) R. apiculata (h& i) R. stylosa 10381044 INDIAN J MAR SCI VOL. 43(6), JUNE 2014 stilt roots. R. apiculata is easily identified by its Present study also recorded Rhizophora hybrids narrow elliptic leaf with acute tip and two flowered in two sites, Havelock and Car Nicobar. In Havelock inflorescence with short peduncle and corky brown Island we recorded 10 hybrid individuals whereas in bract (Fig.10). Flower with small style (0.5 to 1.1 mm) Car Nicobar Rhizophora hybrids are available in good and 9-15 stamens21. R. mucronata and R. stylosa have numbers. In Andaman and Nicobar Islands peduncle length longer than the petiole length and Rhizophora hybrids were first identified by Singh et both looks very similar. One of the key characters al.41 from Havelock islands of South Andaman. that distinguish the R. stylosa from R. mucronata is Thereafter no records are available for Rhizophora style length (Fig. 10). In R. stylosa style length is more hybrids in ANI18. For the first time here we recorded than 2.5 mm26, whereas in R. mucronata the style the Rhizophora hybrids in Kimous Bay, Car Nicobar. length varies from 0.6 to 2 mm21. Apart from style Although Ragavan et al.45 described Rhizophora length, leaf shape and color, propagules length are hybrids in Havelock islands based on the style length, also used to distinguish these two species. R. the taxonomical distinction between R. lamarckii and mucronata has yellowish green broad leaves and R. annamalayana is still unclear. Hence in the present propagules length varies between 40 and 80 cm communication, we describe these taxa as Rhizophora whereas R. stylosa has dark green slightly broad leaves hybrids which are differentiated from other and propagules length varies between 26 cm and 65 Rhizophora species by their tallness, well developed cm21. Fig. 11 depicts the propagules of Rhizophora stilt roots, plenty of flowers and rare occurrence of species and variation in leaf color and shape of the R. propagules. Flowers of Rhizophora hybrids are similar mucronata and R. stylosa in ANI. However, the to flowers of R. apiculata, only difference is that the taxonomical distinction between R. stylosa and R. bracts are corky brown and inflorescence is two mucronata is still unclear, because intermediate forms flowered in R. apiculata whereas in Rhizophora are also present in many places which are difficult to hybrids bracts are smooth and green in color and assign to either taxa44. inflorescences are two to four flowered (Fig. 12). One of the unique features of Indian Rhizophora hybrids is the presence of stamens in two distinct whorls, outer with longer stamens and inner with smaller stamens45.

Figure 12 Cynometra iripa (a) Leaves with off centered mid vein (b) Flowers (c) Wrinkled pod like fruits with lateral beak

Cynometra Within the genus Cynometra, two species i.e. Cynometra ramiflora Linn and Cynometra iripa Figure 11 Rhizophora hybrids (a) Rhizophora hybrids Kostel (Fig. 13) are recognized as mangroves and (left) with Rhizophora mucronata (right) (b) well considered as rare species in ANI16. In the present developed stilt root of Rhizophora hybrids (c-e) 2-4 survey we have identified only C. iripa and it is very flowered inflorescences with smooth green bract (f) common in Andaman Islands. Cynometra species is arrangement of stamens in two rows, inner small and outer large stamens (g) Hybrids with more than 2mm style easily identified by its leaf with off-centered mid vein length (h) less than 2mm style and wrinkled pods. Two species of Cynometra are RAGAVAN et al: FLORAL COMPOSITION AND TAXONOMY OF MANGROVES 10451039

brownish A. speciosum. The easiest diagnostic feature is the leaf tips, which are generally blunt, but with a small point in A. aureum, and elongate-pointed in A. speciosum. Although previous authors mentioned that both the species are abundant in ANI. In this study we encountered A. speciosum in three sites only (Wright myo, Shoal bay and Parangara creek). But in the field we had problems in identifying the A. speciosum because of its similarity with Stenochlaena

Figure 13 Acrostichum species (a-c) A. speciosum (a) habitat palustris. Stenochlaena palustris is climbing fern (b) leaves with pointed tip (c) sporangia (d-f) A. aureum present abundantly in all sites surveyed and exhibit (d)habitat (e) leaves with blunt tip (f) sporangia ( g&h) leaves similar to A. speciosum. Though Dam Roy et comparison between leaf tip of A. speciosum(g) and A. al.31 reported Acrostichum speciosum the photographs aureum (h) in his report was Stenochlaena palustris. So it’s differentiated based on the position of beaks in the understood that the abundance of A. speciosum in ANI pods. C. iripa has prominent lateral beak because the by previous authors was due to the misidentification style is bent in C. iripa, whereas C. ramiflora has Stenochlaena palustris as A. speciosum. sub-terminal beak because it has straight style. Ovary Pemphis acidula is densely hairy in C. iripa and smooth in C. ramiflora. It is the only mangrove species having very small As it is very difficult to distinguish C. iripa and C. leaf. In field Pemphis acidula Forst is (Fig. 15) easily ramiflora without flowering and fruiting, it is possible identified by its appearance very similar to meganthi that C. iripa might have been misidentified as C. tree and mostly occur on coral sand area (Fig. 15). In ramiflora by previous authors16,18. The occurrence of this study we recorded this species only in Havelock C. ramiflora therefore still seems doubtful. Moreover, Island and Carbyn cove area. Duke30 did not include the C. ramiflora as mangrove species. Singh17 and Dam Roy et al.31 also did not report C. ramiflora. Acrostichum According to Tomlinson22 Acrostichum aureum L. and Acrostichum speciosum Willd are (Fig.14) Figure 15 Agecieras corniculatum (a) Leaves (b) flowers (c) considered as minor mangroves but Dagar et al.16, Small sized banana like fruits has not included it in his list. It is the only fern which occurs in mangroves. Generally the occurrence of Aegiceras Acrostichum sp in mangroves is considered as a sign Two species of Genus Aegiceras i.e Aegiceras of degradation as its changes the acidity of the soils. floridum Roemer & Schultes and Aegiceras In general, A. aureum is taller than A. speciosum, corniculatum (L.)Blanco (Fig. 16) are considered as and the young plants are more reddish than the mangrove species, but only A. corniculatum is present in Indian subcontinent. A. floridum is similar to A. corniculatum, but differs due to its smaller leaves, branched (compound) flower clusters (not branched in A. corniculatum) and only slightly curved fruit. Little is known about this species recorded in Figure 14 Pemphis acidula (a) Small sized leaves (b) Fruits Malaysia (Sabah), Indonesia (Java, the Moluccas, (c) Habitat Sulawesi, Borneo, and Papua), Cambodia, Vietnam, INDIAN J MAR SCI VOL. 43(6), JUNE 2014 10401046 the Philippines and Papua New Guinea29. A. corniculatum is easily identified by its rotten banana like fruits often called as Banana of mangroves. Although its leaves are similar to leaf of Ceriops species it is easily differentiated by it apical notch at the tip of leaf which is absent in Ceriops. A. corniculatum is common in Andaman Figure 18 Scyphipora hydrophullacea (a) Varnish coated like Islands (Fig. 16). Leaves (b) Punch of flowers at leaf axial (c) pinkish white flowers

Indian subcontinent, our observations of an extended fruit with a single ridge (longitudinal) infer that Heritiera littoralis Dryn.is the only representative Figure 16 Excoearia agallocha (a) Leaves (b) Cluster of three species of its genus in ANI (Fig. 18). H. fomes has lobed fruits (c) female flowers (d) male flowers sub-globose fruits with longitudinal and transverse ridges whereas H. globosa has rough globose fruits Excoecaria devoid of any ridges. Among the two mangrove species of genus Scyphiphora hydrophyllacea Gaertn.f. Excoecaria (Fig. 17), Excoecaria agallocha L. is recorded from ANI. This species can be readily Scyphiphora hydrophyllacea (Fig. 19) is easily distinguished in the field by its light green and reddish identified by its polished leaf surface and punch of leaves with wavy margin, axillary inflorescence, and flowers at the axial of leaves (Fig. 19). This species is most common in Andaman Islands but it’s very rare in other parts of the India.

Figure 17 Heritieria littoralis (a&b) Pinkish flowers (c ) Fruits with longitudinal ridge ( d) young leaves Figure 19 Mangrove palms (a&b) Phoneix paludosa (a) Fruits poisonous milky latex. Leaves turn orange to a bright (b) Leaves (c-e) Nypha fruticans (c) leaves (d) Flowers (e) shade of red before they are shed, and this gives the Fruits entire tree a reddish appearance. Most common in Mangrove palms Andaman Islands present in land ward edges of the Nypa fruticans Wurmb and Phoenix paludosa mangroves. Sometimes occur along with Rhizophora Roxb. (Fig. 20) are the only mangrove members of and Bruguiera species. Excoecaria indica is not the family Palmaceae. Nypa fruticans is exclusive reported from ANI. It is typically distinguished from mangrove species whereas Phoenix paludosa is found E. agallocha L. by its green fruit the size of a cherry, in landward edges of the mangroves. Both the species and by its thorny trunk7. Moreover fruits in E. are easily identified based on their palm like leaves agallocha are three lobed whereas in E. indica fruits (Fig. 20). Both are most common in Andaman Islands. are round. E. agallocha is only mangrove member Xylocarpus which exhibit dioecious condition i.e. male and female reproductive organs borne on separate individuals of Only two species of the genus Xylocarpus the same species. (Fig. 17). (Fig. 21) are recognized as mangrove species namely Xylocarpus granatum Koen and Xylocarpus Heritiera mekongensis (Prain) Pierre30. Most of the previous Although Heritiera fomes Buch. Ham and researchers in ANI reported three species with an Heritiera globosa Kostermans (Fig. 18) occur in the addition of Xylocarpus molluccensis or Xylocarpus RAGAVAN et al: FLORAL COMPOSITION AND TAXONOMY OF MANGROVES 10471041

whereas in X. granatum 1-2 pairs of leaflets are present46. One more Xylocarpus species which we encountered during the survey is Xylocarpus rumphii (Kostel.) Mabb (Fig. 22). It is beach vegetation recorded in Havelock Island. As it is very rarely found in mangrove swamp it’s generally not considered as mangroves species.

Figure 20 Xylocarpus species (a-d) X. granatum (a) Leaves (b) flowers (c) big seized fruits (d) buttressed trunk (e-h) X.mekongensis (e)young Leaves along with dark red stem with thick peels of bark (f) two pairs of leaflet (g) three pairs of leaflet (h) saucer-shaped pneumatophores (i) Inflorescences (j &k) comparison of bark between X.mekongensis and X.granatum. Figure 22 (a) Fruits of Barringtonia asiatica (b) Leaves of B. asiatica (c-f) Barringtonia racemosa (c) leaves (d) flowers (e) flowers in long spike (f) fruit (g-i) Cassine vibrunifolia (g) capsule like fruits (h) leaves (i) Inflorescences (j-l) Finlaysonia obovata (j) leaves (k) flowers (i) fruits Brownlowia tersa Brownlowia tersa (Fig. 22) is one of the near 5,43 Figure 21 (a) Xylocarpus rhumphii (b) Brownlowia tersa threatened species . The species can be recognized in the field by its greyish brown branches, lanceolate gangeticus, but Xylocarpus molluccensis (Lamk) M. leaves with dull silvery undersurface, and pear-shaped Roem or Xylocarpus gangeticus (Prain.) C.E. woody fruits with two valved carpels. It is one of the Parkinson is a synonym name of Xylocarpus rare mangrove species in ANI43. Hajra et al.47 also mekongensis Pierre29. So there are only two species mentioned that B. tersa was reportedly some 80 years of Xylocarpus in ANI and previous researchers like before, growing abundant nearer to large creeks of Dagar et al.16, Singh and Garge20, Singh17, Debnath18 Middle Andamans and Dhanikhari creek is now rarely and Mandal and Naskar19 appear to have been misled observed there. In the present study we observed this by the nomenclature of Xylocarpus species. X. species in limited population at shayamkund area in granatum is most common in ANI and easily Middle Andaman. identified by its buttressed stem, absence of In this study Kandelia candel has not been pneumatophores, obovate leaves and large fruits with recorded from any site. Although it is very similar to pyramidal seeds. X. mekongensis is distinguished from Rhizophora species it can easily be distinguished by X. granatum by its saucer shaped pneumatophores its reflexed calyx lobes i.e sepals, spindle-shaped and dark stem with thick peels of bark29. In this study hypocotyls (thickest in the middle and tapering to both we recorded X. mekongensis in three sites. Generally ends) and absence of above ground roots. Similarly Leaves are paripinnate in both the species. In X. Aegialitis rotundifolia and Aglaia cucullata also has mekongensis the leaves have 1, 2 or 3 pairs of leaflets not been recorded from any site. Singh17 and Dam 10481042 INDIAN J MAR SCI VOL. 43(6), JUNE 2014

Roy et al.31 also had not reported this species in ANI. Cassine viburnifolia (Juss.) Ding Hou and So it may be inferred that Kandelia candel, Aglaia Barringtonia asiatica (L.) Kurz are not reported by cucullata and Aegialitis rotundifolia might have Debnath18 and Mandal and Naskar19. We, however, become extinct from ANI. Dagar16 and Debnath18 also recorded these species in the present study (Fig. 23). mentioned that the existence of Aegialitis rotundifolia, C. vibrunifolia is recorded only in Baratang Island. Kandelia candel and Aglaia cucullata are needed to B. asiatica is recoded in Havelock and Car Nicobar be confirmed whether they become extinct or Island (Fig. 23). Most interestingly in most of the sites misidentified by previous authors. Other doubtful we observed that Finlaysonia obovata Wall. is present species in ANI are Ceriops decandra, Sonneratia in the bank of creeks along with Rhizophora, apetala, Cynometra ramiflora and Bruguiera Bruguiera, Ceriops and Xylocarpus species and these sexangula. species experience tidal fluctuations similar to true mangrove species. However, Tomlinson22 treated F. Among the 33 species reported six species i.e obovata as mangrove associate; based on the present Acanthus volubilis, Xylocarpus mekongensis, observation here we proposed the inclusion of F. Pemphis acidula, Brownlowia tersa, Sonneratia ovata obovata in minor components. F. obovata is easily and Sonneratia griffithii are very rare and confined identified by its obovate leaves and buffalo horn like to limited population. So immediate efforts should fruits (Fig. 23). taken to protect and propagate the above mentioned species to prevent their local extinction. Also it is Fig. 23 to be given important to pay special attention to conserve the Conclusion natural hybrids of genus Rhizophora because natural Present study needed standardization of fieldwork hybrids play a very important role in evolution of over the 2-year period of the study using the existing novel gene combinations and a mechanism of diagnostic identification keys and analysis of basis speciation48. Moreover, Rhizopora hybrids rarely of identifications used by different researchers. In produce seeds, making its propagation very difficult. order to generate effective management plans for Mangrove associates conservation and management of mangroves, it is There is no consensus opinion on mangrove necessary to monitor the important coastal vegetations associates among researchers due to the lack of on periodical intervals. proper definition to distinguish clearly between the Acknowledgements mangrove and non-mangrove species. so it is not Authours are grateful to Dr. Norman Duke, James appropriate to compare species composition of Cooks University, Australia and Dr. K. Kathiresan mangrove associates with other authors Following are CAS in Marine Biology, Annamalai University, and the mangroves associates found most frequently in Tamil Nadu for their valuable suggestions in preparing many sites: Ardisia elliptica, Barringtonia asiatica, this manuscript. Barringtonia racemosa, Caesalpinia bonduc,Caesalpinia crista, Calophyllum inophyllum, References Cassine vibrunifolia, Cerbera odollum, 1. Kathiresan, K. & Bingham, B.L., Biology of mangrove Clerodendrum inerme, Dalbergia candenatensis, and mangrove ecosystems. Advances in Marine Biology, Derris trifoliata, Derris scandens, Fimbristylis 40 (2001) 81251. ferruginea, Finlaysonia obovata, Flagellaria indica, 2. Kathiresan, K. & Qasim, S.Z., In Biodiversity of Mangrove Hibiscus tiliaceus, Hoya parasitica, Intsia bijuga, Ecosystems. (Hindustan Publishing Corporation, New Delhi) 2005, pp. 1- 251. Ipomoea pes-caprae, Melastoma saigonense, 3. FAO., Status and trends in mangrove area extent worldwide. Pandanus odoratissimus, Pluchea indica, Sarcolobus In: Wilkie ML, Fortuna S, editors. Forest Resources carinatus, Sarcolobus globosus, Scaevola sericea, Assessment working Paper No. 63.Rome: (Forest Sesuvium portulacastrum and Thespesia populnea. Resources Division, FAO) 2003 87p. RAGAVAN et al: FLORAL COMPOSITION AND TAXONOMY OF MANGROVES 10491043

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