Journal of Threatened Taxa | www.threatenedtaxa.org | 26
November 2019 | 11(14): 14870–14875
Cordia diffusa K.C. Jacob, the Kovai
Manjack (Boraginaceae):
a highly threatened steno-endemic species from Coimbatore City, Tamil Nadu, India
S. Arumugam 1, K.
Sampath Kumar 2, B. Karthik 3 & V. Ravichandran
4
1,3,4 Botanical Survey of India,
Southern Region Centre, TNAU Campus, Lawley
Road P.O., Coimbatore,
Tamil Nadu 641 003, India.
2 Research
& Development Centre, Bharathiar University,
Coimbatore, Tamil Nadu 641046, India.
1 grassindia11@gmail.com,
2 rksambath@gmail.com (corresponding author), 3 karthikbr1711@gmail.com,
4 ravichandran725@gmail.com
Abstract: Cordia
diffusa K.C. Jacob, belonging to Boraginaceae, discovered in 1938 and named by K.C. Jacob in
1944, is a little-known and the only narrow endemic but neglected plant of
Coimbatore City. The lectotype of the
steno-endemic is determined and the current status, distribution, potential
threats, bioprospecting potential, and suggestions for conservation of the
species are discussed. The collection of
steno-endemic plant during intensive exploration in its type locality nearly after
90 years is of phytogeographic and conservation significance. The endemic is proposed the category of
Critically Endangered (CR) based on criterion D of IUCN (as per versions 3.1
& 13). C. diffusa
can be protected by promoting awareness of the rarity of native species and
mass propagation through vegetative means so as to introduce it in gardens,
parks, and avenues, etc. at once in the city.
Keywords: Conservation, endemic shrub, lectotypification,
status, threats.
doi: https://doi.org/10.11609/jott.5292.11.14.14870-14875
Editor:
N.P. Balakrishnan, Coimbatore,
Tamil Nadu, India. Date of publication: 26 November 2019
(online & print)
Manuscript
details: #5292 | Received 31
July 2019 | Final received 06 November 2019 | Finally accepted 10 November 2019
Citation: Arumugam, S., K.S. Kumar, B.
Karthik & V. Ravichandran (2019).
Cordia diffusa K.C. Jacob, the Kovai Manjack (Boraginaceae): a highly
threatened steno-endemic species from Coimbatore City, Tamil Nadu, India. Journal
of Threatened Taxa
11(14): 14870–14875; https://doi.org/10.11609/jott.5292.11.14.14870-14875
Copyright: © Arumugam et al. 2019. Creative Commons Attribution 4.0 International
License. JoTT
allows unrestricted use, reproduction, and distribution of this article in any
medium by adequate credit to the author(s) and the source of publication.
Funding: None.
Competing interests: The authors declare no competing interests.
Acknowledgements: The authors are thankful
to the Dr. A.A. Mao, director, Botanical Survey of
India, Kolkata, for his kind support and encouragement; and to Dr. C. Murugan, scientist-E, BSl-SRC, Coimbatore, for his help and cooperation in
providing necessary facilities. Our
thanks are also due to Dr. A. Rajasekaran,
scientist-C, Institute of Forest Genetics and Tree Breeding, Coimbatore, for
his cordial support and kind help to locate the plant in the IFGTB campus. KSK profoundly thanks all the timely generous
favors and friendly rapport by Mr. N. Vikraman, MSc MTech, Nodal Officer, NABARD, Aizwal, Mizoram; and thanks Research & Development
Centre, Bharathiar University, Coimbatore, for
providing the support and resources. We
wish to express our appreciation and
cordial thanks to the esteemed Reviewer for the valuable comments and
suggestions to improve and refine the content.
Understanding rarity has been an important task among
plant ecologists and also vital in conserving biodiversity while the process of
rarity has diverse ecological consequences. Steno- or strict endemic species
have a small, non-dominant, constantly sparse plant population size and are
characterised by their narrow habitat specificity and geographically restricted
in a specific habitat (Rabinowitz 1981).
Species with narrow distribution range and/or fewer individuals are
considered to be most prone to extinction due to changing climatic conditions
and competition from alien species (Chitale et al.
2014). Human-induced perturbations
resulting in habitat loss is identified as one of the important causes of
rarity, though several intrinsic factors also govern the distribution and
survival of species in their natural habitats.
The conservation of narrow endemics that are threatened or endangered
has become a major concern shared by governments, conservation organisations,
and individuals (Kruckeberg & Rabinowitz
1985). Species not collected in herbaria
for several decades have been one of the valuable yardsticks for judging the
rarity status of the species (Meher-Homji 1995).
Coimbatore, the district headquarters and the third
largest city of Tamil Nadu, is located between 11.0160N, and 76.9550E
with an approximate altitude of 470m, extending over an area of 105km2,
inhabited by over two million urban population
(https://coimbatore.nic.in/). Coimbatore
City, bounded on the west by the Western Ghats, Noyyal
(Noyyil) river running to the south, while the east
and the north are coverd by vast stretches of fields
mainly of black cotton soil (Chandrabose 1981; Chandrabose & Nair 1988). The city limit has expanded as the
metropolitan area of the city has increased from 38.28km2 in 1973 to
62km2 in 1981 to 274.34km2 in 2010, owing to the rapid
urbanisation and expanding population.
It is also one of the most industrialised cities of Tamil Nadu
(Anonymous 2015).
Coimbatore City area was botanically sporadically
explored since 1826 by renowned botanists such as C.A. Barber, K.C. Jacob, Colonel
Cox, J.L. Elllis, and later by M. Chandrabose,
Girija Lakshmanan, T.R. Somasundaram, K. Subramanyam,
H. Sundanda Kamath, and others. The Flora of Coimbatore published by Chandrabose & Nair (1988) recorded c. 850 taxa by
exploring about 258km2 over a period of 10 years in the city and its
environs. Of these, three taxa (Polygala
jacobii Chandrabose
(1968), Euphorbia hypericifolia L. var. coimbatorensis Chandrabose
(1988), and Cordia diffusa KC Jacob (1944))
were reported as endemic to the region, but C. diffusa,
restricted to the city limits, is the only stenoendemic
species as of now. Polygala jacobii, treated as an unresolved name in the Plant
List, is a Indo-Sri Lankan rare endemic herb distributed in Karnataka,
Kerala, Madhya Pradesh, Maharashtra, and Tamil Nadu in India (Kulkarni &
Singh 1973;
http://florakarnataka.ces.iisc.ac.in/hjcb2/herbsheet.php?id=3666&cat=1),
and E. hypericifolia L. var. coimbatorensis is now synonymised under Euphorbia
indica Lam. (Plant List 2019; POWO 2019).
Taxonomic History & Phytogeography
The genus Cordia L. (Boraginaceae
sensu lato and Cordiaceae sensu stricto), native to tropical and subtropical regions, is
diverse with c. 250–350 widespread species (Mabberley
2008; Balachandran & Rajendiran 2016). In India, the genus is represented by about
20 species, of which 13 species have been recorded so far from Tamil Nadu
(Ramamurthy 1987; Balachandran & Rajendiran 2016)
including three endemics, viz., Cordia diffusa
K.C. Jacob, C. domestica Roth, and C. ramanujamii Balachandran & Rajendiran,
all are shurbs or small trees. C. domestica is distributed in Western Ghats of Madurai
and Nilgiris districts and also reported to be
cultivated (Ramamurthy 1987), while C. ramanujamii
is a recently discovered endemic species from the Pakaam
Malai Reserve Forest, Ginjee,
Eastern Ghats, Tamil Nadu, at an altitude of 350m (Balachandran & Rajendiran 2016).
A new Cordia species was discovered by Dr. K. Cherian Jacob on 02 May 1938, based on the
collections from Nanjundapuram, about 8km south of
Coimbatore, and was later named as Cordia diffusa
K.C. Jacob (1944). This species was
included in the enumeration of rare and threatened plants of southern India by
Henry et al. (1978), and it was determined as Indeterminate on the IUCN Red
List of Threatened Plants (Rao et al. 2003).
Based on the specimens available at MH, it was revelaed
that this rare narrow endemic species was collected by K. Subramanyam in 1959
(MH: 7784) and was last collected by Chandrabose in
1968 from nearby the type locality, as well as from the Forest College
compound, R.S. Puram, Coimbatore. The
steno-endemic, however, has not been collected or recorded since 1968. It was stated by Chandrabose
& Nair (1988) that Cordia diffusa, is also
on the verge of extinction due to rapid urbanisation, industrialisation and
other anthropogenic activities. They
further reiterated that conservation of the species in this highly disturbed
area would be a challenge. In the light
of these facts, we made thorough explorations in and around the type locality
to determine the current status of the species.
Prabhu et al. (in press) report the collection
of the species from the Forest College Campus, Insitute
of Forest Genetics and Tree Breeding (IFGTB), Coimbatore, in their
phytochemical screening and bioactivity studies. There is, however, no extant population of
the plant in the Forest College, IFGTB Compound. The bush from which the collection was
reportedly made was found cleared from the garden of IFGTB. A few stem cuttings of the removed plant are
being kept now for propagation of the species (Fig. 1G). Hence, the authors made intensive surveys for
the plant in its type locality for about one year and could recollect the
species in flowers and fruits from the dry open wastelands along the railway
track, Nanjundapuram area, Coimbatore, in May
2018. A population of just 10
individuals were observed in the type locality, and the plant was straggling in
the dry open wasteland with black cotton soil and almost always associated with
Capparis sp., besides Calotropis
gigantea, Morinda
tinctoria, etc.
The habitat of the endemic plant was highly disturbed by human
interferences particularly plastics, polythene, bottles and other garbage found
strewn around the habitat. From the
pertinent literature, it was revealed that this species was not collected from
its type locality after the type collection by K.C. Jacob in 1938. Hence, the present collection of C. diffusa from its type locality, nearly after 90 years
is of phytogeographic and conservation significance of this little-known
species. There are, however, collections
from nearby areas along Vaalankulam Lake in western
Coimbatore (see specimens examined). The species was supposedly recently recorded
from the Gulf of Mannar, eastern coast, by Daniel
& Umamaheswari (2001). The rare occurence
of the endemic species from the mainland coast as well as from the Karaichalli Island, Thoothukudi
(Tuticorin) District, Gulf of Mannar Bioisphere Reserve, is intriguing and is the only record of
C. diffusa from the coast and far away from
its type locality. Nevertheless, the
cited specimens in the Flora (P. Daniel & P. Umamaheswari
103325, 107301; S.A. Muthukumar 104746) could not be
traced at MH. Hence, the disjunct
distribution of this narrow endemic is intriguing and needs further
investigations.
The reported distribution of C. diffusa
K.C. Jacob in Chengalpattu District (Ramamurthy 1987; Nayar
1996; Singh et al. 2015), and in the Deccan (Ahmedullah
& Nayar 1987) is doubtful as there are no
specimens from these regions available in MH. Daniel & Umamaheswari
(2001) also concluded that the endemic species was earlier reported from
Coimbatore only.
Systematic Treatment
Cordia diffusa
K.C. Jacob in J. Bombay Nat. Hist. Soc. 45: 78.
1944; A.N. Henry et al. in J. Bombay Nat. Hist. Soc. 75: 692. 1978; K.
Ramamurthy in A.N. Henry et al., Fl. Tamil Nadu 2: 97. 1987; M. Chandrabose & N.C. Nair in Fl. Coimbatore 190. 1988; P.
Daniel & P. Umamaheswari in
Fl. Gulf of Mannar 279, t.37. 2001. Gerascanthus diffusus
(K.C. Jacob) Borhidi, Acta Bot. Hung. 34: 404. 1988
(Image 1).
Lectotype: INDIA, Tamil Nadu, Coimbatore District, near Nanjundapuram, 1,330ft (c. 400m), railwayline,
02 May 1938, K.C. Jacob 86237A, MH Acc. No. 175500! designated here; Isolectotypes: K.C. Jacob 86237 B, C, D & E, MH Acc.
Nos. 175501!–175504! Paratype: Tank Road, near Railway station, c. 400m, 23
March 1942, K.C. Jacob s.n., MH 175505!
Specimens examined: India, Tamil Nadu, Coimbatore District, Vaalankulam, along railway line, 467m, K. Subramanyam 7784,
10 February 1959, MH Acc. Nos. 15269!, 15270!;
Ramanathapuram, 469m, M. Chandrabose
28852, 21 November 1965, MH 55200!, 55201!; Forest College Compound, R.S.
Puram, 468m, M. Chandrabose 29876, 07 May 1968, MH
Acc. Nos. 57090!, 570901!; Vaalankulam side, 467m, M.
Chandrabose 30292, 02 July 1968, MH Acc. Nos. 57455!,
57456!; M. Chandrabose 30577, 02 August 1968, MH Acc.
Nos. 57601!, 57602!; R.S. Puram, Botanical Garden, IFGTB Campus, Gurudev Singh & C.K. Jeyachandran
17681, 13 October 1987, FRC (n.v.); Near Nanjundapuram, c. 410m, along railway line, K. Sampath
Kumar 997, 29 April 2018, MH (Image 2).
Shrubs, straggling, spreading, c. 1m high; branches
many, woody, spreading in all directions, lenticellate;
younger parts tawny pubescent. Leaves
3–7 x 2.0–3.5 cm, simple, alternate or opposite, exstipulate, broadly elliptic-oblong,
acute or obtuse at apex, shortly mucronate, rough, coriaceous, dentate,
scalloped along margins, dark green above, pale beneath; midrib prominent
beneath, nerves prominent, 6–8 pairs; rough hairy on both surfaces, petiole c.
0.3–0.5 cm long, pubescent.
Inflorescences in terminal 8–12 flowered umbellate cymes; peduncle
simple, c. 2cm long. Flowers ebracteate, pedicels 2–4 mm long.
Calyx tubular, brown, tomentose, c. 5mm long; fruiting calyx saucer-shaped,
margins brown, tomentose. Corolla white, tubular, c. 8mm long, lobes 4,
linear-oblong, prominent and reflexed, fragrant. Stamens 4, antisepalous,
epipetalous, exserted; anthers pale brownish, sagitate; filaments adnate to the base, free at the top,
white, glabrous.
Style terminal, simple below, bipartite, branches again bipartite, pale
yellow; stigma simple, white. Ovary
4-loculed, c. 2mm long, greenish. Drupes ovoid-acute, mucronate, 1–1.5 x
0.8–1.2 cm, greenish when young, bright ornage when
ripe, edible, pulp sugary, viscid, with cup-shaped, fulvous pubescent,
irregularly many lobed persistent calyx; 1-seeded; seeds globose, orange,
shiny, 5–8 x 4–6 mm.
Flowering and fruiting: Almost throughout the year.
Current Status
Based on the field surveys, consultation of herbarium
specimens of earlier collections including types at MH, review of pertinent
literature (Jacob 1944; Henry et al. 1978; Ramamurthy 1987; Ahmedullah
& Nayar 1987; Chandrabose
& Nair 1988; Daniel & Umamaheswari
2001), it is infered that the extant population of
the steno-endemic may not exceed 50 mature individuals and the area of
occupancy is very small and restricted covering less than 5km2. Owing to the small and inferred continued
declining population size, and the number of mature individuals in the extant
population being less than 50, it is proposed that the species be categorized
as Critically Endangered (CR) based on criterion D for restricted number of
mature individuals as per the guidelines of the IUCN Red List Categories &
Criteria (versions 3.1 & 13; IUCN 2001, 2017). Hence, conservation of the species requires
immediate and inevitable actions to avoid the possible extinction in the near
future.
Threat Factors and Conservation Strategies
Human interference with the environment in recent
times has greatly accelerated the pace of extinction, though extinctions have
also taken place in the past mainly due to natural causes. But, endangered plant species, compared with
endangered animals, attract rather little public attention (Sivarajan
1991). As per the recent estimates, the
extinction rate of seed-bearing plant species is 500 times faster than in other
species (Ledford 2019).
The flora of Coimbatore and its environs obviously is
much disturbed due to regular biotic interferences. The popluations of C.
diffusa in its type locality are found rare and
becoming endangered, and conserving this species in such a highly disturbed
area would be really a challenge (Chandrabose 1981; Chandrabose & Nair 1988). During the present survey in the type
locality, it was identified that the human interference has been the major
threat factor, and dumping of used polythenes,
plastics, glasswares, waste materials, debris of
buildings, and persistent clearing of vegetation along the tracks by the
railway all leading to the habitat destruction and degradation, besides the
increasing pollution, rapid urbanisation and industrialisation in the city
area. The lack of awareness about the
endemic plant of the city also results in the removal of the stands in the
wild.
As the plant is shrubby and can be easily propagated
by stem cuttings (Fig. 1G), it can be mass propagated at the earliest and
introduced in city gardens and in other suitable habitats in and around the
city so as to conserve the species.
Awareness of the steno-endemic should be created among the public
particularly among the school children and college students; and vegetative
propagules may be distributed by the concerned agencies or through local ‘plant
protection’ societies and environment / nature clubs to save the plant in
peril. The micropropagation studies on
the highly threatened endemic plant must be given high priority. The in vitro repository of plant propagules
may be deposited at the National Bureau of Plant Genetic Resources (NBPGR)
towards long-term ex situ conservation of the species.
Ex situ conservation through seed, pollen, gene and
germplasm banks may also be considered to preserve the species outside its
natural habitats. Reproductive
biological studies may provide important perspectives to help preserve the
genetic potential which are crucial for restoration and reintroduction.
Potential Uses/ Bioprospecting
There are lesser chances to collect and name the
missing species before they become extinct and the information about potential
uses or unique properties of such native plants need to be passed on (Sharp
1964; Raven 1976). With the scanty literature and the limited
herbarium collections, Cordia diffusa remains
a poorly known plant.
The traditional uses, phytochemistry and pharmacology
of the 36 medicinal species of the genus Cordia have been reviewed
recently (Oza & Kulkarni 2017), wherein c. 300
phytochemical compounds of various classes present in the 36 species has been
documented. The traditional uses, diversity of phytochemicals, pharmacological
properties, and biological activities of C. dichotoma
discussed in the review by Jamkhande et al. (2013);
and the presence of apigenin in the bark of C. dichotoma
showed significant healing and reduction in inflammatory enzymes of ulcerative
colitis (Ganjare et al. 2011). The protective effect of bark extract of C.
macleodii against Naja
venom poisoning was reported by Soni & Bodakhe (2014). The
reputed use of bark from C. rothii in heart
ailments in Gujarat has also been recorded (Chauhan & Chavan 2009). Similarly, the leaves C. diffusa has been studied recently for its antioxidant
activity and phytochemical consitutents (Prabu et al.
in press). Thus, C. diffusa has the potential for further bioprospection
studies using vegetatively propagated materials or in
vitro raised plant parts to avoid collecting from the wild.
Conclusions
Ex situ conservation measures for the narrow endemic
plant of Coimbatore City, Cordia diffusa K.C.
Jacob, must be initiated immediately. In
situ conservation of the wild populations will be most challenging in the light
of serious habitat loss owing to the burgeoning population, ever-increasing
pollution, rapid urbanisation and industrialisation, besides possible impacts
of global climate change. Hence,
effective steps to promote awareness of the rarity and conservation
significance of the unique shrub of the city among the public and particularly
students are the need of the hour. As
the shrub seems to establish easily by asexual mode, multiplication through
stem cuttings in nurseries and distribution of vegetatively
propagated plant saplings to gardeners may be given top priority, besides
introducing it in public and private gardens.
Further studies on bioprospection and in vitro clonal propagation
are vital. The disjunct distribution of
the endemic plant in the region needs further research. Field explorations and regular monitoring of
the extant populations in the fragile habitats of the city environs may reveal
the current status of other native taxa.
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