**3.2 Distribution**

For an understanding based on geographical distribution the 107 endemic species that recorded from the CC plains were divided into eight groups and their representations are: 1. India (excluding Himalayas & north east) (6 species), 2. Peninsular India (22 species), 3. Southern India (28 species), 4. Southern India with one or two states of north India (11species), 5. Eastern and Western Ghats (5 species), 6. Eastern Ghats (5 species), 7. Tamil Nadu (27 species) and 8. Dispersed in different states (3 species) (**Figure 5**). The distribution of six species across the country is *Crotalaria pusilla*, *Dolichandrone falcata* and *Hardwickia binata, Iseilema anthephoroides, Lophopogon tridentatus* and *Scleria stocksiana* (**Figure 6**). *Crotalaria willdenowiana*, *Deccania pubescens* var. *candolleana*, *Polycarpaea corymbosa*, *Pterocarpus santalinus* and *Sterculia populifolia* were spotted only in EGs of Andhra Pradesh, Karnataka and Tamil Nadu (**Figure 7**). Five species *viz*. *Derris ovalifolia*, *Mallotus resinosus* var. *muricatus*, *Mussaenda glabrata, Rhynchosia courtallensis* and *Tetrastigma tamilnadense* was found both in EG and WG (**Figure 7**). At regional


**Table 1.**

*Correlation of endemic plants life form and threat status with disturbance gradience.*

**Figure 4.**

*Disturbance index with life-form and threat status.*

*Endemic Vascular Plants from the Coromandel Coast of Tamil Nadu, Southern India DOI: http://dx.doi.org/10.5772/intechopen.94333*

**Figure 5.**

*Geographical representation of endemics at regional and district level of Tamil Nadu.*

**Figure 6.** *Representation of endemic plants distributed at national and regional level.*

### *Endangered Plants*

level south India has 28 species followed by 27 species restricted to Tamil Nadu and 22 taxa represented from peninsular India (**Figure 5**).

The representations of species at different districts of Tamil Nadu are analysed, and the study shows that the species found in only one (17 species), two (17 species), three (13), four – many (51 species) and in all districts (9) were recorded (**Figure 5**).

#### **3.3 Narrow or steno endemics**

Thirteen species were showed very narrow distribution, found in only one district. They are *Acrachne henrardiana* of Poaceae (Pudukkottai district)*, Barleria*

**Figure 7.** *Representation of endemic plants distributed at state level and RET endemics.*

*Endemic Vascular Plants from the Coromandel Coast of Tamil Nadu, Southern India DOI: http://dx.doi.org/10.5772/intechopen.94333*

*durairajii* of Acanthaceae (Thoothukudi)*, Caralluma adscendens* var. *gracilis* of Apocynaceae (Pudukkottai), *Cordia ramanujamii* of Cordiaceae (Villupuram), *Derris gamblei* of Leguminosae (Pudukkottai), *Huberantha senjiana* of Annonaceae (Villupuram), *Jatropha villosa var. ramnadensis* of Euphorbiaceae (Ramanathapuram)*, Lepidagathis pungens* of Acanthaceae (Tirunelveli)*, Leucas anandaraoana* of Lamiaceae (Ramanathapuram)*, Polycarpaea diffusa* and *Polycarpaea majumdariana* of Caryophyllaceae (Thoothukudi and Tirunelveli)*, Sporobolus hajrae* of Poaceae (Pudukkottai) and *Theriophonum sivaganganum* of Araceae (Ramanathapuram); of which C. ramanujamii and H. senjiana are recently described neo-endemics (**Figure 8**).

### **3.4 Disjunct distribution**

The analysis shows interesting disjunctions between: 1. The districts of Tamil Nadu, 2. SI and north-east and 3. SI and north-west, and 4. SI and trans-Himalaya (**Figure 9**). *Garnotia elata* of Poaceae and *Glossocardia bosvallia* of Asteraceae are sharing their region between SI and Uttar Pradesh; *Indigofera mysorensis* of Leguminosae and *Jatropha tanjorensis* of Euphorbiaceae between SI and West Bengal; *Manisuris myurus* of Poaceae between SI & Manipur; *Oldenlandia attenuata* of Rubiaceae between EG and Uttar Pradesh; *Leucas diffusa* between SI and Delhi;

**Figure 8.** *Recently described endemic species.*

**Figure 9.** *Representation of state and district level distribution of endemics.*

*L. wightiana* and *Senna montana* between SI and Gujarat; and *Tricholepis radicans* between SI and Rajasthan are some important disjunct distributions between two major geographical regions (**Figure 10**).

In Tamil Nadu at district level analysis (**Figure 9**) found that *Blumea eriantha* of Asteraceae (Coimbatore-Villupuram), *Chlorophytum malabaricum* of Asparagaceae (Nilgiri-Villupuram), *Cordia diffusa* of Cordiaceae (Coimbatore-Kancheepuram), *Drypetes porteri* of Euphorbiaceae (Theni-Villupuram), *Justicia beddomei* of Acanthaceae (Tirunelveli-Villupuram), *Melothria angulata* of Cucurbitaceae (Dindigul-Villupuram), *Mussaenda tomentosa* of Rubiaceae (Tirunelveli-Villupuram), *Rhynchosia courtallensis* of Leguminosae (Tirunelveli-Villupuram), *Tetrastigma tamilnadense* of Vitaceae (Tirunelveli-Villupuram) and *Trachys narasimhanii* of Poaceae (Chennai-Ramanathapuram) are showing great disjunction between the north and south district (**Figure 10**).

## **3.5 Doubtful endemics**

There are six species *viz*. *Ceropegia mannarana* of Apocynaceae, *Leucas nepetifolia* of Lamiaceae, *Mariscus clarkii* of Cyperaceae, *Stenosiphonium parviflorum* of Acanthaceae *Sehima sulcatum* and *Zenkeria elegans* of Poaceae are considered as doubtful endemics because Singh et al. [2], Krishnamurthy et al. [34], Henry et al. [35] and Ahmedullah & Nayar [10] treated them as endemic whereas the www.pla ntsoftheworldonline.org for the former four species and Kabeer & Nair [13] for the latter two Poaceae members had marked them as non-endemic. Meanwhile, Krishnamurthy et al. [34] was included the two latter species under "endangered" list.

### **3.6 Threat status**

According to IUCN [36], a total of 90 (84.11%) out of 107 endemic species were listed as "not evaluated" and their population status in the wild habitats is also unknown. So far, only seven species *viz*., *Aglaia elaeagnoidea* (LC [37]), *Decalepis hamiltonii* (EN-A2cd, [38]), *Drypetes porteri* (EN-B1 + 2c, [39]), Koilodepas calycinum (EN B1 + 2c, [39]), *Lindernia minima* (EN-B1ab + 2ab, [40]), *Pterocarpus santalinus* (EN-B1 + 2de, [41]), and *Sterculia populifolia* (CRD, [39]) are assessed according to IUCN criteria (**Figure 7**). From the published information found that 10 species such as, *Chrysopogon verticillatus* [13], *Crotalaria willdenowiana* [34], *Derris ovalifolia* [34, 42, 43], *Dipcadi montanum* var. *madrasicum* [10, 44], *Discospermum sphaerocarpum* [45], *Justicia beddomei* [10], *Leucas wightiana* [10],

*Endemic Vascular Plants from the Coromandel Coast of Tamil Nadu, Southern India DOI: http://dx.doi.org/10.5772/intechopen.94333*

**Figure 10.** *Disjunct distribution of endemics.*

*Melothria angulata* [22], *Rhynchosia courtallensis* [34] and *Sarcostemma intermedium* [34] were came to known as rare or endangered or threatened endemic species.

### **3.7 Threat assessment and conservation measures**

Rapid Assessment Workshop on Conservation of Tropical Dry Evergreen Forest was conducted by Auroville Green Group, Auroville in collaboration with Foundation for Revitalization of Local Health Traditions, Bengaluru held between 5 and 7 March, 2002. A team of 32 field botanist and experts involved and assessed 48

**Figure 11.** *Conservation status of* Hildegardia populifolia *and its habitat.*

species but not published, in which 11 species such as *Acrachne henrandiana*, *Aglaia elaeagnoidea, Cadaba trifoliata*, *Caralluma indica*, *Carissa salicina*, *Ceropegia juncea*, *Derris ovalifolia*, *Discospemum sphaerocarpum* (syn. *Tricalysia sphaerocarpa*), *Habenaria roxburghii*, *Manisuris myurus*, and *Pterospermum xylocarpum* are endemic.

Since 1996, extensive effort was employed by Auroville Green Group to conserve on Tropical Dry Evergreen Forest, is an endangered forest type in India. More than one lakh seedlings from 250 native species produced every year planted and developed 'Green Ring' in 2000 hectares at Auroville. Basically they attempted to conserve all the TDEF species; in addition they were concentrated on endemic, endangered and rare Indo-Sri Lankan elements too. Few such endemic species are *Commiphora berryii*, *Deccania pubescens, Derris ovalifolia*, *Discospermum sphaerocarpum, Dolichandrone atrovirens, Dolichandrone falcata*, *Drypetes porteri, Hardwickia binata, Justicia beddomei, Manilkara roxburghiana, Miliusa eriocarpa, Pterocarpus santalinus*, *Pterospermum xylocarpum, Sterculia populifolia* and so on. They are standardised the germination through different techniques for most species but they are not successful in *Terminalia paniculata* of Combretaceae and two non-endemic native species *viz*. *Anogeissus latifolia* of Combretaceae and *Hugonia mystax* of Linaceae.

#### *3.7.1* Sterculia populifolia*, threat assessment: a status survey*

The conservation status of *Hildegardia populifolia* (syn of *Sterculia populifolia*) was kept in different category by the experts of India. This species was assessed first as 'Critically Endangered' by The World Conservation Monitoring Center WCMC [13] (**Figure 11**) and there are no update to till date. Literature screening showed with other categories as viz. 'Endangered' by Krishnamurthy et al. [34], Walter and *Endemic Vascular Plants from the Coromandel Coast of Tamil Nadu, Southern India DOI: http://dx.doi.org/10.5772/intechopen.94333*

Gillet [46]; 'Vulnerable' by Reddy et al. [47]; 'Very Rare' by Rao and Pullaiah [48]. Whereas Sarcar and Sarcar [49] studied the population, propagation and conservation of the species and recommended the species as critically endangered. Madhavachetty et al. [50] was reported this species occurrence from Ankalamma Konda in Chittoor district. Recently Jaikrishnan [51] was made intensive population survey, counted all mature individual and assessed the new recruits at Gingee hills of Villupuram District, Tamil Nadu and finally concluded this species as 'critically endangered'. The taxa which are under threatened status since 1997 categorised by IUCN and Botanical Survey of India was published Red data books in three volumes during 1987–1990, in which *Hildegardia populifolia* was also treated as endangered.

#### **4. Discussion**

The floral diversity in any state or country or world the dominant families are Leguminosae, Poaceae, Orchidaceae, Acanthaceae, Euphorbiaceae, Asteraceae, Apocynaceae, and Rubiaceae so on. This present endemic study was more intrinsically matching with, regional [52] and national [1, 2] studies/analysis. Also, the study reports from the coastal plains [26, 53–58] favoured the present study. Out of 107 endemics 27 species are restricted to the state Tamil Nadu, 5 to EG, 5 to EG & WG, 28 to SI, 11 species sharing between SI with different states of north India, 22 to PI, to entire India, and 3 to elsewhere. These data were enlightened the richness of plant diversity at the Coromandel coast, especially from the TDEF of Tamil Nadu and supporting the 'coastal zone' as one of the endemic centres of India.

The International Union for Conservation of Nature and Natural Resources [46] assessed the global threat status of 33,418 species of Angiosperms, of which 1215 species are reported from India, of which 690 (55.8%) species were evaluated as Indeterminate (I). From this study 80% of endemic species were in 'not evaluated' category. According to Isik [59] three-quarters of narrow endemic species of plants and animals are known to have become extinct due to habitat loss or fragmentation. So as Nair [60] statement "it is very essential that rare, threatened and presumed extinct taxa should be repeatedly searched for in their type localities", should be strictly followed and need to do their population assessment status from time to time. Narrow range and regional level assessments are making ambiguous with the IUCN category, so the WCMC should follow these publications and update them to the relevant species.

Majority of endemic species are isolated due to geographical, ecological, edaphic and climatic barriers and these fragmented patches of vegetation were more pronounced in EG for the point of conservation [61, 62]. This condition was more privileged to the narrow endemic species like *Cordia ramanujamii*, *Huberantha senjiana* and *Mussaenda tomentosa* at Pakkam Malai reserve forest; Gingee hills of EG [53]. Meanwhile, the disjunctly distributed species like *Blumea eriantha*, *Cyanotis tuberosa*, *Drypetes porteri*, *Derris ovalifolia*, *Discospermum sphaerocarpum*, *Indigofera mysorensis*, *Justicia beddomei, Leucas wightiana*, *Manisuris myuros*, *Melothria angulata* between the two Ghats/bioregion have to be considered as crucial for the conservation actions.

It was estimated that 2–25% of plant species will become extinct or committed to extinction in tropical forest approximately in next years [63]. It is also opined that 22–47% of species might have already become threatened [64]. In India TDEF occupies about 2482.52 km2 (1.61% of the country territory), in which Tamil Nadu has only 41.08 km<sup>2</sup> (0.1%) [65]. According to Krishnamurthy et al. [34] the TDEF found along the Coromandel Coast is an 'endangered forest' type. The degree of threat and richness of endemism is one of the major aspects in prioritising the areas for conservation. In this paradigm, Jain & Rao [66] statement "if endemic species are eliminated from our country it will mean that they will be annihilated from the whole world, will be loss to science, will be struck off the roles of biological resources of this earth" should be profoundly considered. In all, highly fragmented form of TDEF ecosystem, indeterminate IUCN status of narrow endemics and their disjunct distribution with different bioregions of India should be considered as high priority for the assessment and conservation programs at national, regional and state level in regular intervals.
