New Record of Equisetum ramosissimum subsp

New Record of Equisetum ramosissimum subsp. debile from Lower Gangetic Plain, West Bengal, India and Conservation Approach Mithun Biswas, Aninda Mandal, Madhuparna Hore, Subikash Biswas, Suvendu Dey, Jayita Biswas, Amrik Mondal, Bidyut Kumar Mandal, et al. Proceedings of the National Academy of Sciences, India Section B: Biological Sciences ISSN 0369-8211 Proc. Natl. Acad. Sci., India, Sect. B Biol. Sci. DOI 10.1007/s40011-015-0698-3

1 23

Your article is protected by copyright and all rights are held exclusively by The National Academy of Sciences, India. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com”.

1 23

Author's personal copy Proc. Natl. Acad. Sci., India, Sect. B Biol. Sci. DOI 10.1007/s40011-015-0698-3

RESEARCH ARTICLE

New Record of Equisetum ramosissimum subsp. debile from Lower Gangetic Plain, West Bengal, India and Conservation Approach Mithun Biswas1 • Aninda Mandal1,2 • Madhuparna Hore1 • Subikash Biswas1 Suvendu Dey1 • Jayita Biswas1 • Amrik Mondal1 • Bidyut Kumar Mandal1 • Piu Das1 • Sudha Gupta1

•

Received: 10 August 2015 / Revised: 29 October 2015 / Accepted: 7 December 2015 The National Academy of Sciences, India 2016

Abstract A recent survey for pteridophytic flora in the lower Gangetic plain of West Bengal, India reports the natural occurrence of Equisetum ramosissimum Desf. subsp. debile (Roxb. Ex Vauch.) Hauke (Equisetaceae) from alluvial Gangetic zone of North 24 Parganas district (22550 39.0000 N and 88260 14.9400 E) which adds new record to the existing database of pteridophytic flora in the region. Regular observations show that the population of E. ramosissimum is sustained completely by vegetative means due to non-formation of reproductive organ i.e. strobilus in an individual plant in any season. The community analyses through standard ecological methods reveal heterogeneous phyto-assemblages in both winter and rainy seasons, however, seasonal variations are observed in species diversity and frequency. Simpson’s Index of Diversity in both plant communities suggests diverse species richness and evenness in the area. Importance Value Index depicts ecological dominance of E. ramosissimum in both seasons. The plant has significant positive correlation with angiospermic taxa, Mikania micrantha and Typha angustifolia in winter and rainy seasons, respectively but is negatively correlated with Xanthium indicum and Desmostachya bipinnata, correspondingly. These observations may be taken into consideration for in situ conservation of the species. Systematic conservation plan is suggested to protect this newly revealed taxon, E. ramosissimum subsp.

& Sudha Gupta [email protected] 1

Department of Botany, Pteridology and Palaeobotany Section, University of Kalyani, Kalyani, West Bengal 741235, India

2

Present Address: Department of Botany, A. B. N. Seal College, Cooch Behar, West Bengal 736101, India

debile which demands regular awareness program among local people for continued future sustainability as the area is regularly invaded by human footsteps. Finally, the present investigation may motivate the young workers for field study to explore the nature in better way. Keywords Wetland Pteridophytic flora Quadrat method Community analyses Importance Value Index Simpson’s Index of Diversity

Introduction Equisetum L. (English name: Horsetail) is one of the ancient pteridophytic plants belonging to family Equisetaceae, the only remnant of Sphenopsida [1]. The plant group Sphenopsida was one of the major contributors of global coal forest during Permo-Carboniferous time which had cosmopolitan palaeogeographic distribution in tropical low lying areas having warm and humid climate [2–4]. The group first appeared in the late Devonian, became diverse and abundant in the Palaeozoic swamp forest as arborescent horsetails, and gradually declined during Meso-Cenozoic time [5]. In recent times, it is represented by only one living genus Equisetum with herbaceous nature considered as a ‘living fossil’ [1, 5, 6]. At present, the genus is represented worldwide by fifteen living species [1, 7–9] of which only four (E. arvense L., E. diffusum D. Don, E. palustre L., and E. ramosissimum Desf.) are from India [10]. Among the available Indian species E. palustre has already been treated as ‘Critically Endangered’ by International Union for Conservation of Nature (IUCN) [11] but the IUCN status of remaining species is not exactly known. Equisetum is a perennial and evergreen plant possessing immense therapeutic uses [12–15]. Nowadays scientists are

123

Author's personal copy M. Biswas et al.

much concerned to conserve the germplasm(s) of important plant resources like Equisetum through proper conservation plan as the rate of biodiversity loss is increasing day by day. In general, it is apparent that several biotic and abiotic factors like habitat loss and fragmentation, overexploitation, pollution, invasions of alien species and global climate change are the major causes behind such decreasing tendency of natural reserves. However, time to time update of biodiversity surveys in regional and global scale is

compulsory by qualitative and quantitative assessment of the taxa to know the exact status of a particular species in a particular area. Rigorous field study is one of the important tools for the purpose. The present investigating group undertook a project of thorough field study for pteridophytic flora in the lower Gangetic plain of West Bengal as a part of conservation approach. The study reveals the new realm of naturally growing E. ramosissimum subsp. debile at Gangetic alluvial

Fig. 1 Map showing study area (marked in map pointer and circle) (Map courtesy: Google Map)

123

Author's personal copy New Record of Equisetum ramosissimum subsp. debile from Lower Gangetic Plain, West Bengal…

zone of North 24 Parganas district of West Bengal. The finding is significant as it is a new addition to the pteridophytic flora of the lower Gangetic plain of West Bengal. In addition, the community analysis was performed in two seasons (rainy and winter) to understand the phyto-association of E. ramosissimum as an important parameter for consideration of in situ conservation system of the plant.

Material and Methods

24 Parganas district of West Bengal, India (Fig. 1). The North 24 Parganas district lies between 23150 200 and 22110 600 N latitude and between 8950 and 88200 E longitude comprising of 4094 km2 area in the lower Gangetic plain of the province. Average rainfall of the area is 1.5779 mm; temperature varies from a maximum of 41 C in May to a minimum of 10 C in January and relative humidity ranges between 50.0 and 90.0 % [16]. Soil character is clay loamy type with 8.03 and 7.70 pH values in winter and rainy seasons, respectively as measured from collected soils.

Physiographic Features of the Study Area

Sampling Plot and Estimation Design

The study area is situated within a wetland locally named as cutting bill or Bhutbagan Pukur (22550 39.0000 N and 88260 14.9400 E), adjacent to Halisahar railway track in North

The total study area was measured around 392 m2, mostly covered with Cynodon dactylon, like that in open grassland. Season wise community analysis had been performed

Fig. 2 Morpho-anatomical features, propagation mode, of E. ramosissimum subsp. debile. a General appearance, b aerial stem showing ridges and furrows, c sub serial stem with roots, d leaf sheath with brown colored teeth, e T.S. of aerial stem showing valecular canal

(vc) and carinal canal (cc), f, g vegetatively propagated plants from fluted aerial stems

123


by quadrat method. In an individual season a total of 10 quadrats were laid randomly to avoid biased sampling. The minimum size of the quadrat was 4 m2 in rainy and 1 m2 in winter seasons. Data Analyses The qualitative assessments of the enumerated taxa and their preliminary identification was done by comparing the herbarium specimens kept in Herbaria (acronym KAL) of Botany Department, University of Kalyani, West Bengal, India. Taxonomic description and identification of the plant Equisetum had been ascertained by considering morphoanatomical characters of the vegetative plant body only due to total lack of reproductive structures in the population in all seasons. Identification of associated angiospermic taxa has been authenticated by Prof. S. K. Mukherjee, Taxonomist of Botany Department, University of Kalyani. Standard ecological methods [17] were pursued for quantitative analysis of data. The vegetation was analytically computed following the parameters like frequency, density, abundance, relative density, relative frequency, and importance value index. Raunkiaer’s [18] frequency class was followed to categorize the species to understand the distribution of a species throughout an association. The comparative study of plant diversity in both seasons was determined by using Simpson’s Index of Diversity [19]. Pearson’s correlation coefficient analysis was calculated between Equisetum and other associated plant taxa in the community to ascertain inter-specific correlation(s), if any.

beneath each ridge. The cortical parenchyma consists of large intercellular passages i.e. vallecular canals. Centrally placed hollow pith is surrounded by vascular bundles. Each vascular bundle is typically characterized by the presence of carinal canal, a unique feature of Equisetum. It is interesting to proclaim that reproductive organs (strobili) in the plant body are totally lacking as evinced from regular observations since last 2 years. The plant is found to propagate entirely by vegetative means. The vegetative propagation has been done by fluted aerial stems from perennial rootstocks (Fig. 2f, g). Non-formation of strobili in present Equisetum population is definitely a constraint to complete the reproductive cycle, possibly due to the presence of moderate microhabitat in comparison to its native locale as previously suggested by Peck [20] in different pteridophytic plants. As such, vegetative mode of propagation seems to be an important ecological attribute in the studied ecosystem. In spite of limited number of species [15], the Equisetum plant has successfully adapted to grow in diverse ecological conditions due to its unique feature of rhizomatous clonal growth [7, 21], which is significant in tracing the geographical and geological continuity of the genus since Jurassic [22, 23]. The key characters of the plant Equisetum (more than 1 meter long mature main stem with whorl branches and brown colored sheath tubes) as suggested earlier by Zhang

Results and Discussion Morpho-Anatomical Description and Mode of Propagation Aerial stem is jointed, hollow, smooth, dark green, irregularly branched, measuring up to 200 cm in height and 0.5–0.7 cm in diameter with 8–20 ridges; primary branches solitary or in groups of 2–8 extending up to 20 cm, straight or sinuous (Fig. 2a, b). Sub-aerial stem or rhizome of individual plant is long, creeping, branched, and dark brown (Fig. 2c). Roots are fibrous, present along the length of the rhizomes (Fig. 2c). Leaves minute, scaly, present in whorls that are fused in a sheath at stem nodes; sheath tightly attached, 0.5 cm long, lanceolate-acuminate; sheath with persistent or often deciduous teeth; teeth dark brown, with narrow white margins and a hair like apex (Fig. 2d). The transverse section of aerial stem (Fig. 2e) shows wavy outline representing ridges and furrows. Epidermis is single layered with sunken stomata restricted to the furrow zone only. Sclerenchymatous hypodermis is present

123

Fig. 3 Distribution of E. ramosissimum subsp. debile in India (shaded area—previous record; star—present report) (Map courtesy: Google Map)


and Turland [24] are well in conformity for identification of the species as E. ramosissimum. Further, the absence of branching in young main stem identifies the sub-species as E. ramosissimum subsp. debile. E. ramosissimum Desf. possesses two subspecies (E. ramosissimum subsp. debile (Roxb. Ex Vauch.) Hauke and E. ramosissimum subsp. ramosissimum Maire) which are reported to grow naturally in forests, forest margins, grazing land, scrublands, and river bank at sea level to 3200 m altitude in southern and eastern Africa, southern and central Europe, central and south America, and throughout Asia [24, 25]. Majority of published literatures documented the existence of only one subspecies E. ramosissimum subsp. debile (Roxb. Ex Vauch.) Hauke in southeast Asia including India [24]. The present study also

corroborates the statement by exploring natural domicile of E. ramosissimum subsp. debile in the lower Gangetic plain of West Bengal. However, Parihar and Parihar [14] reported the occurrence of E. ramosissimum subsp. ramosissimum Maire from the province of Madhya Pradesh in India. The published literature, checklist for World Ferns and the database of the ENVIS Centre on floral diversity, Botanical Survey of India, reported the presence of E. ramosissimum subsp. debile (Roxb. Ex Vauch.) Hauke predominantly in different north Indian provinces (Delhi, Haryana, Rajasthan, Uttar Pradesh, and Jharkhand) and to a lesser extent in Madhya Pradesh of central India, Tamil Nadu of south India, and Arunachal Pradesh, Assam, Meghalaya of east India [25–31]. No published

Table 1 Community analysis in the studied area showing ecological attributes Plant species

Frequency (%) Frequency class

Density

Abundance

Relative frequency

Winter

Winter Rainy Winter Rainy Winter Rainy

Importance value

Winter Rainy

Winter Rainy Winter Rainy

Equisetum ramosissimum

100.00 90.00

E

E

60.400 104.500 60.400

116.111 16.393 6.977 0.304

0.142 16.697 7.118

Alternanthera sessilis

30.00

80.00

B

D

2.200

7.333

43.375

4.918

0.047 4.929

Ampelopteris prolifera

80.00

70.00

D

D

16.600 27.500

20.750

39.286

13.115 5.426 0.084

Cassia sophera

–

90.00

–

E

–

8.800

–

9.778

–

6.977 –

0.012 –

6.989

Centella asiatica

60.00

–

C

–

2.000

–

3.333

–

9.836

–

–

–

Cestrum diurnum

30.00

40.00

B

B

0.600

11.600

2.000

29.000

4.918

3.101 0.003

0.016 4.921

3.117

Coix gigantea

–

30.00

–

B

–

16.500

–

55.000

–

2.326 –

0.022 –

2.348

Colocasia esculenta

70.00

70.00

D

D

10.100 6.200

14.429

8.857

11.475 5.426 0.051

0.008 11.526 5.435

Cynodon dactylon

80.00

100.00 D

E

97.300 380.500 121.625 380.500 13.115 7.752 0.489

0.516 13.604 8.268

Desmostachya bipinnata –

70.00

–

D

–

48.200

–

68.857

–

5.426 –

0.065 –

Diplazium esculentum

–

50.00

–

C

–

14.700

–

29.400

–

3.876 –

0.020 –

3.896

Hydrophyllum sp.

20.00

–

A

–

0.300

–

1.500

–

3.279

–

–

–

Hyptis pectinata

20.00

30.00

A

B

0.600

0.500

3.000

1.667

3.279

2.326 0.003

0.001 3.282

2.326

Hyptis suaveolens Ricinus communis

– –

60.00 40.00

– –

C B

– –

13.400 4.100

– –

22.333 10.250

– –

4.651 – 3.101 –

0.018 – 0.006 –

4.669 3.106

Lantana camara

–

30.00

–

B

–

3.600

–

12.000

–

2.326 –

0.005 –

2.330

Mikania micrantha

80.00

80.00

D

D

6.300

10.400

7.875

13.000

13.115 6.202 0.032

0.014 13.146 6.216

Parthenium hysterophorus

–

80.00

–

D

–

15.700

–

19.625

–

6.202 –

0.021 –

6.223

Phyla nodiflora

–

30.00

–

B

–

1.000

–

3.333

–

2.326 –

0.001 –

2.327

Sida rhombifolia

–

50.00

–

C

–

1.800

–

3.600

–

3.876 –

0.002 –

3.878

Solanum nigrum

–

30.00

–

B

–

1.600

–

5.333

–

2.326 –

0.002 –

2.328

Stephania sp.

–

30.00

–

B

–

1.600

–

5.333

–

2.326 –

0.002 –

2.328

Typha angustifolia

–

30.00

–

B

–

24.000

–

80.000

–

2.326 –

0.033 –

2.358

Urena lobata

–

60.00

–

C

–

2.100

–

3.500

–

4.651 –

0.003 –

4.654

Vitis trifolia Xanthium indicum

– 40.00

50.00 –

– B

C –

– 2.400

4.600 –

– 6.000

9.200 –

– 6.557

3.876 – – 0.012

0.006 – – 6.569

3.882 –

34.700

Rainy

Relative density

6.202 0.011

0.010

0.002

6.249

0.037 13.198 5.464 9.846

5.492

3.280

Raunkiaer’s law of frequency [18]: A: 1–20 %; B: 21–40 %; C: 41–60 %; D: 61–80 %; E: 81–100 %

123


Winter

Rainy

records of Equisetum spp. are available from the lower Gangetic plain of West Bengal [32, 33], and therefore the present finding is first of its kind which eventually adds new observation to the pteridophytic flora in the area (Fig. 3).

Equisetum ramosissimum

604

1045

Community Analyses


22

347


166

275

Cassia sophera

00

88

Centella asiatica

20

00

Cestrum diurnum

06

116

Coix gigantea

00

165

Colocasia esculenta

101

62

Cynodon dactylon

973

3805

Desmostachya bipinnata

00

482


00

147

Hydrophylum sp.

03

00

Hyptis pectinata

06

05

Hyptis suaveolens Ricinus communis

00 00

134 41

Lantana camara

00

36

Mikania micrantha

63

104


00

157

Phyla nodiflora

00

6310

Sida rhombifolia

00

18

Solanum nigrum

00

16

Stephania sp.

00

16

Typha angustifolia

00

240

Urena lobata

00

21

Vitis trifolia

00

46

Xanthium indicum

24

00

Simpson’s Index of Diversity

0.65

0.70

Table 2 Total number of plants in all the sampled quadrats in two seasons and their values of Simpson’s Index of Diversity Plant species

Fig. 4 Bar diagram showing frequency percentage of different classes in the communities during winter and rainy seasons

123

Total number of plants in all the sampled quadrats

Quantitatively the Equisetum plants are present in good frequency throughout the year. Habitat of the plants is terrestrial, although the lowland area is waterlogged due to heavy rain during monsoon. The associated plant taxa and their frequency differ seasonally. The plant community in winter consists of mostly fully grown Equisetum plant along with 9 species of angiosperm, and 1 species of fern, albeit the phyto-assemblage varies during rainy season both qualitatively and quantitatively (Table 1) by the presence of 20 taxa of angiosperm, and 2 fern taxa along with immature Equisetum population. Though the community analysis has not been performed during summer season, but almost identical vegetation pattern is observed like that of winter. The associated plant taxa in winter are Alternanthera sessilis, Ampelopteris prolifera, Centella asiatica, Cestrum diurnum, Colocassia esculenta, Cynodon dactylon, Hydrophyllum sp., Hyptis pectinata, Mikania micrantha, and Xanthium indicum and that in rainy are Alternanthera sessilis, Ampelopteris prolifera, Cassia sophera, Cestrum diurnum, Coix gigantea, Colocassia esculenta, Cynodon dactylon, Desmostachya bipinnata, Diplazium esculentum, Hyptis pectinata, H. suaveolens, Ricinus communis, Lantana camara, Mikania micrantha, Parthenium hysterophorus, Phyla nodiflora, Sida rhombifolia, Solanum nigrum, Stephania sp., Typha angustifolia, Urena lobata,


Vitis trifolia. The commonly found plant species in both the seasons are Alternanthera sessilis, Ampelopteris prolifera, Cestrum diurnum, Colocassia esculenta, Cynodon dactylon, Hyptis pectinata, and Mikania micrantha. The species diversity seems to be more in rainy than winter but the Simpson’s Indices of Diversity are almost same in both the seasons, i.e. 0.70 and 0.65, respectively (Table 2). The higher and more or less similar values of the Simpson’s Index of Diversity in the plant community in both the seasons suggest diverse species richness and evenness in the area which needs to be protected against anthropogenic pressure for continued future sustainability as the area is regularly invaded by human footsteps.

According to Raunkiaer’s law of frequency [18], all the plant species present in both communities (winter and rainy) are grouped into 5 frequency classes (A: 1–20 %, B: 21–40 %, C: 41–60 %, D: 61–80 %, E: 81–100 %; Table 1). The frequency diagram (Fig. 4) of the community in both the seasons shows that the percentage of frequency class A is 16.67 in the winter, but no plant taxa falls under the same class during monsoon. The classes B, C, D are represented by 25.0, 8.33, and 33.33 % in winter, whereas the corresponding values in the rainy season are 39.13, 21.74 and 26.09 %. The remaining class E is represented by 16.67 and 13.04 % during winter and monsoon, respectively. Community structures have been assessed by

Fig. 5 Graphical representation of Importance Value Index of different plant species in the communities during winter and rainy

123


comparing the value of each frequency class with Raunkiaer’s normal frequency value which makes it evident that the community in both the seasons are truly heterogeneous in having higher sum values of frequency classes B, C, and D (66.66 in winter and 86.96 in rainy) than the normal ones as recommended by Raunkiaer’s law as under. A [ B [ C T D\E A comparative diagram has been plotted to illustrate the Importance Value Index of E. ramosissimum and all other associated plants grown in the area seasonally (Fig. 5). The value ranges from 16.697 (E. ramosissimum) to 3.280 (Hydrophyllum sp.) in winter and 8.268 (C. dactylon) to 2.326 (H. pectinata) in monsoon. In a community, all species cannot be equally important, and therefore the ecological dominance is played by one or a few species which have major controlling influence based on their number, size or population. In the present findings, the Importance Value Index of individual species during winter depicts the highest ecological dominance of E. ramosissimum (16.697) sequentially over C. dactylon (13.604), A. prolifera (13.198), M. micrantha (13.146) and so on. During monsoon, the grass species C. dactylon precedes major ecological role having highest importance value (8.268) and E. ramosissimum stands in second highest position (7.118) over other plant taxa. Thus, E. ramosissimum has a major influence in the community by virtue of its greater importance value which can protect and provide shelter to other organisms and may also be capable of influencing the physical environment also. Correlation coefficient analyses indicate both positive and negative significant relationships between E. ramosissimum and other associated plant taxa (Table 3). Positive and significant correlation of Equisetum is found with Mikania micrantha in winter (r = 0.644) and Typha angustifolia in rainy (r = 0.609); while, significant and negative correlations exist with Xanthium indicum in winter (r = -0.705) and Desmostachya bipinnata in rainy (r = -0.639). Strong positive association of E. ramosissimum subsp. debile with angiosperm taxa M. micrantha in winter and with T. angustifolia in rainy indicates the importance of these two plants for the establishment and formation of better population size of Equisetum in respective season. The growth of X. indicum in winter and D. bipinnata in rainy may be one of the detrimental factors for the expansion of E. ramosissimum population in the area as established by strong negative correlation. The present findings may help to protect this medicinally important ancient germplasm by keeping the positively associated plants in the habitat and by removing the negatively associated plants from the habitat to acquire better population size during in situ or ex situ conservation program in future.

123

Table 3 Correlation analysis of E. ramosissimum subsp. debile with associated plants in two seasons Taxa

Seasons Rainy

Winter


-0.046

0.09


0.537

0.504

Cassia sophera Centella asiatica

0.159 –

– 0.418

Cestrum diurnum

0.547

0.235

Coix gigantea

0.371

–

Colocasia esculenta

0.071

0.469

Cynodon dactylon

-0.537

-0.145

Desmostachya bipinnata

-0.639

–


0.054

–

Hydrophyllum sp.

–

-0.408

Hyptis pectinata

-0.013

-0.535

Hyptis suaveolens

-0.122

–

Ricinus communis

-0.195

–

Lantana camara

-0.345

–

Mikania micrantha

-0.494

0.644


-0.443

–

Phyla nodiflora Sida rhombifolia

-0.301 0.239

– –

Solanum nigrum

0.116

–

Stephania sp.

-0.014

– –

Typha angustifolia

0.609

Urena lobata

-0.159

–

Vitis trifolia

-0.447

–

Xanthium indicum

–

-0.705

Values in bold font are significant at 5 % level (Degree of Freedom = 9)

Conclusion The conservation of this newly explored site at Halisahar area in North 24 Paganas district of West Bengal is of utmost important as this is the only place in the lower Gangetic plain, so far known, for natural growth of E. ramosissimum subsp. debile in a rich and diverse plant community throughout the year. Regular monitoring using random sampling by quadrat method is suggested to understand the dynamics of the habitat and communities and accordingly plan for their management. It is needless to say that the human beings play a vital role both in maintaining as well as in destroying the biodiversity of an area. In the light of this, efforts are being made by the investigating team along with Halisahar Bigyan Parishad (Non Government Organization) to make aware the common people regarding the significance of conservation of natural plant resources in present wetland ecosystem.


However, more attempts are to be needed for their active participation. Considering the importance of wetland values and benefits in an ecosystem an initiative has been taken to communicate West Bengal Biodiversity Board, Department of Environment, Government of West Bengal, India to implement necessary measures for conserving the wetland including the Equisetum inhabiting area in proper way. Finally, the authors suggest vigorous field survey to explore the nature in better way and to update the existing database of the flora in regional and at global scale by knowing the present and the actual status of the explored plants which might avoid the theoretical conjecture on the status of the plant community. Acknowledgments This study was supported by the grant (41-489/ 2012(SR) dated 16th July 2012) from the University Grants Commission, New Delhi, India. The authors are thankful to Mr. Tridip Kanti Dastidar and Mr. Amlyan Kumar Bairagi of Halisahar Bigyan Parishad (Non Government Organization) for their kind help during field study. We are grateful to Prof. Animesh Kumar Datta, Department of Botany, University of Kalyani for his valuable suggestions and kind help.

References 1. Gifford EM, Foster AS (1989) Morphology and evolution of vascular plants. Freeman, New York 2. Delevoryas T (1962) Morphology and evolution of fossil plants. Holt, Rinehart and Winston, New York 3. Pearson LC (1995) The diversity and evolution of plants. CRC Press, Boca Raton 4. Bashforth AR, Zodrow EL (2007) Partial reconstruction and palaeoecology of Sphenophyllum costae (Middle Pennsylvanian, Nova Scotia, Canada). Bull Geosci 82:365–382. doi: 10.3140/bull.geosci.2007.04.365 5. Stewart WN, Rothwell GW (1993) Paleobotany and the evolution of plants. Cambridge University Press, Cambridge 6. Xue X, Fry SC (2012) Evolution of mixed-linkage (1 - [ 3, 1 - [ 4)b-D-glucan (MLG) and xyloglucan in Equisetum (horsetails) and other monilophytes. Ann Bot 109:873–886. doi:10.1093/aob/mcs018 7. Hauke RL (1963) A taxonomic monograph of the genus Equisetum subgenus Hippochaete. Beheifte Nova Hedwigia 8:1–123 8. Hauke RL (1978) A taxonomic monograph of the genus Equisetum subgenus Equisetum. Nova Hedwigia 30:385–455 9. Hauke RL (1990) Equisetaceae. In: Kramer KU, Green PS (eds) Pteridophytes and gymnosperms. The families and genera of vascular plants, vol 1, Springer, Berlin, pp 46–48. doi: 10.1007/978-3-662-02604-5_12 10. Fraser-Jenkins CR (2008) Taxonomic Revision of three hundred Indian subcontinental Pteridophytes with a Revised Census-List-a new picture of fern-taxonomy and nomenclature in the Indian subcontinent: 1-c.595 11. Fraser-Jenkins CR (2012) Rare and threatened pteridophytes of Asia 2. Endangered species of India—the higher IUCN categories. Bull Natl Mus Nat Sci Ser B 38:153–181

12. Kapur SK, Sarin YK (1977) Useful medicinal plants from Jammu and Kashmir. Indian Drugs 14:136–140 13. Singh HB (2003) Economically viable pteridophytes in India. In: Chandra S, Srivastava M (eds) Pteridology in the new millennium, NBRI golden jubilee volume. Kluwer, Netherlands, pp 421–446 14. Parihar P, Parihar L (2006) Some pteridophytes of medicinal importance from Rajasthan. Nat Prod Radiance 5:297–301 15. Singh S, Singh R (2013) Utilization of pteridophytes of Achanakmar-Amarkantak biosphere reserve, Central India in women’s health and beauty care practices. Int Res J Pharm 4:235–240 16. http://north24parganas.gov.in. Accessed 30 July 2015 17. Magurran AE (1988) Ecological diversity and its measurement. Princeton University Press, Princeton. doi: 10.1007/978-94-015-7358-0 18. Raunkiaer C (1934) The life form of plants and statistical plant geography. The Clarendon Press, Oxford, p 632 19. Simpson EH (1949) Measurement of diversity. Nature 163:688. doi:10.1038/163688a0 20. Peck CJ (1985) Reproductive biology of isolated fern gametophytes. Retrospective theses and dissertations, Iowa State University, Ames, Iowa, paper 8762 21. Husby C (2013) Biology and functional ecology of Equisetum with emphasis on the giant horsetails. Bot Rev 79:147–177. doi: 10.1007/s12229-012-9113-4 22. Rothwell GW (1996) Pteridophytic evolution: an often underappreciated phytological success story. Rev Paleobot Palynol 90:209–222. doi:10.1016/0034-6667(95)00084-4 23. Channing A, Zamuner A, Edwards D, Guido D (2011) Equisetum thermal sp. nov. (Equisetales) from the Jurassic San Agustı´n hot spring deposit, Patagonia: anatomy, paleoecology, and inferred paleoecophysiology. Am J Bot 98:680–697. doi: 10.3732/ajb.1000211 24. Zhang LB, Turland NJ (2013) Equisetaceae. In: Wu ZY, Raven PH, Hong DY (eds) Flora of China, vol 2–3 (Pteridophytes), Science Press, Beijing, pp 67–72 25. http://homepages.caverock.net.nz/*bj/fern/equisetum.htm. Checklist of World Ferns-world species list. Accessed 30 July 2015 26. http://bsienvis.nic.in/Database/Wetlands_3943.aspx. Accessed 30 July 2015 27. Dixit RD (1984) A census of Indian Pteridophytes. Botanical Survey of India, Calcutta 28. Cook CDK (1996) Aquatic and wetland plants of India. Oxford University Press, New York 29. Chandra S, Fraser-Jenkins CR, Kumari A, Srivastava A (2008) A summary of the status of threatened pteridophytes of India. Taiwania 53:170–209 30. Singh BP, Upadhyay R (2012) Aquatic pteridophytes diversity of Hoshangabad Madhya Pradesh, India. Asian J Sci Technol 4:045–049 31. Singh B, Singh VN, Phukan SJ, Sinha BK, Borthakur SK (2012) Contribution to the pteridophytic flora of India: Nokrek Biosphere Reserve, Meghalaya. J Threatened Taxa 3:2277–2294 32. Sen T, Chakraborti K, Rahaman S, Bandhyopadhyay M, Sen U (2010) Biodiversity of pteridophytes of Sunderban, India; and their in situ conservation. Nat Acad Sci India B 80:201–220 33. Sen T, Sen U, Chakraborty K, Rahaman S, Paul R (2011) Floral survey of ferns of Nadia district, West Bengal. Indian Fern J 28:85–104

123