Journal of Threatened
Taxa | www.threatenedtaxa.org | 26 December 2023 | 15(12): 24420–24426
ISSN 0974-7907
(Online) | ISSN 0974-7893 (Print)
https://doi.org/10.11609/jott.8698.15.12.24420-24426
#8698 | Received 18
August 2023 | Final received 11 October 2023 | Finally accepted 22 November
2023
Notes on Discospermum
sphaerocarpum Dalzell ex Hook.f.,
a rare species of Rubiaceae (Ixoroideae:
Coffeeae) from southern India
C. Pramod 1, V.V. Drisya 2, A.K. Pradeep 3 &
K.T. Chandramohanan 4
1,3 Department of Botany, University
of Calicut, Calicut University P.O., Kerala 673635, India.
2,4 Department of Botany, Government
Brennen College, Dharmadam P.O., Thalassery,
Kerala 670106, India.
1
cpramod4@gmail.com (corresponding author), 2
drisyachandran96@gmail.com,3 akpradeep1@uoc.ac.in, 4
chandrubrennen@gmail.com
Editor: Shiny Mariam Rehel,
Keystone Foundation, Kotagiri, India.
Date of publication: 26 December 2023 (online & print)
Citation: Pramod, C., V.V. Drisya, A.K. Pradeep &
K.T. Chandramohanan (2023). Notes on Discospermum sphaerocarpum
Dalzell ex Hook.f., a rare species of Rubiaceae (Ixoroideae: Coffeeae) from southern India. Journal of Threatened Taxa 15(12):
24420–24426. https://doi.org/10.11609/jott.8698.15.12.24420-24426
Copyright: © Pramod et al. 2023. Creative Commons Attribution 4.0 International
License. JoTT
allows unrestricted use, reproduction, and distribution of this article in any
medium by providing adequate credit to the author(s) and the source of
publication.
Funding: This study was not funded by external sources.
Competing interests: The authors declare no competing interests.
Author details: C. Pramod—specialized in angiosperm taxonomy and floristics, has started his career at Government Victoria College, Palakkad as an assistant professor in 2007, and presently working at the Department of Botany, University of Calicut. A.K. Pradeep—an expert in the family Malvaceae and angiosperm floristics, has about 35 years of research experience in angiosperm taxonomy; started career at Government Mahatma Gandhi College, Androth
and joined
University of Calicut in 1995. V.V. Drisya is a
PhD research scholar at the Department of Botany, Government Brennen College, Thalassery under Kannur University. K.t. Chandramohanan—started his professional career in 2005 at Government Brennen College, Thalassery and presently is the principal, Krishna Menon Memorial Government Women’s College, Kannur.
Author contributions: Design of the study, field surveys and communications—CP; Assistance and support in the field surveys—VVD, AKP & KTC; Laboratory studies—CP & VVD; Preparation of the first draft of the manuscript—CP, VVD & AKP; Critical comments for the preparation of the final manuscript—CP, VVD, AKP & KTC; All authors read and approved the final manuscript.
Acknowledgements: The authors are grateful to Dr. S.E. Dawson and Dr. A.P.
Davis, Herbarium Royal Botanic Gardens, Kew, for their help in identification;
and to the head of the Department, University of Calicut, Kerala, and the
Principal, Government Brennen College, Kerala, for the facilities provided for
the study.
Abstract: Discospermum sphaerocarpum is a rare species
in the tribe Coffeeae
of the family Rubiaceae and its occurrence on the Madayippara lateritic plateau of the Kannur district of
Kerala, southern India is discussed. This plant is endemic to southern India
and Sri Lanka. In Kerala, this species was previously recorded from the
low-altitude evergreen forests of Thiruvananthapuram district. The present
study gives a detailed description, distribution and figures & images
illustrating the diagnostic characters of D. sphaerocarpum
for easy identification and conservation.
Keywords: Conservation, endemism, laterite
ecosystems, Madayippara, sacred groves.
INTRODUCTION
The genus Discospermum
Dalzell ex Hook.f. comprises 13 species, mainly
shrubs or trees, growing primarily in wet tropical biomes with native ranges
from India to the Philippines (POWO 2023). In India, Discospermum
is represented by three species, D. sphaerocarpum Dalzell
ex Hook.f., D. apiocarpum
Dalzell ex Hook.f., and D. abnorme
(Korth.) S.J. Ali & Robbr.
The former two species were reported in southern India and the latter one from
Assam. D. sphaerocarpum is a medium-sized tree
which grows in dry and wet tropical biomes and it is native to southern India
and Sri Lanka (POWO 2023).
The genus was originally
described by Dalzell in 1850 from Sri Lanka. Later, Hooker (1880) reduced the
genus Discospermum to a section of Diplospora. This synonymy was widely accepted until
Ali & Robbrecht (1991) revived Discospermum. To resolve the issue of the generic
position of asian species classified as Tricalysia or Diplospora,
Ali & Robbrecht (1991) reviewed traits of asian Diplospora/Tricalysia species, and
proved that the Asian species cannot be accommodated within the African genus Tricalysia; and Discospermum,
which was included in the synonymy of Diplospora
for over a century, was reinstated at generic rank. They found that the two
genera differ in placentation, fruit size and fruit wall texture, the number of
seeds per locule, seed shape, and exotestal cell
anatomy. Using molecular techniques, Arriola et al. (2018) have shown that Diplospora and Discospermum
represent separate lineages in the tribe Coffeeae.
Molecular investigations by Tosh et al. (2009) further supported the decision
to keep Diplospora and Discospermum
as two distinct genera.
Another much-debated topic was
the taxonomic placement of this genus. Initially, Discospermum
was placed in the tribe Gardenieae. Robbrecht & Puff (1986) emended the circumscription of Gardenieae to include Tricalysia
and Diplospora. Subsequently, Ali & Robbrecht (1991) attributed generic status to Discospermum, and included it in the Gardenieae
subtribe Diplosporinae. They stated that Discospermum “links the Diplosporinae
with the Gardeniinae and supports the rank (subtribe)
given to these”. Results of the phylogenetic study by Andreasen & Bremer
(2000) do not support such a relationship and they concluded that at least some
genera of Diplosporinae belong to Coffeeae.
In a recent study, Davis et al. (2007) expanded the circumscription of Coffeeae and confirmed the placement of Discospermum
in this tribe based on plastid sequence data and morphological data set.
Previous reports of the species Discospermum sphaerocarpum
in India were from the wet and dry evergreen forests from the coast to high
altitudes (50–1,000 m) of the Western Ghats regions of Kerala, Tamil Nadu,
Karnataka, Goa, and Maharashtra (Singh et al. 2015). Gamble (1921) reported the
species from Courtallum of Tinnevelly
(Tirunelveli) district of Tamil Nadu; later distribution record extended to Cuddalore and Villupuram districts and Coromandel coast (Narayanasami & Natesan 2020).
In Kerala, D. sphaerocarpum was earlier
reported from the low-elevation evergreen forests of Thiruvananthapuram
district (Sasidharan 2004). This species now has been
recorded from a totally different habitat close to seashore, the sacred groves
of a Lateritic hill of Madayippara at an altitude of
less than 50 m in the Kannur district (Pramod & Pradeep 2020, 2021).
During a botanical exploration of
the Madayippara lateritic plateau of southern India
in 2008, the authors encountered a rare Rubiaceae
member in vegetative condition in two patches of vegetation associated with
sacred groves. The identity of the species remained a mystery as no flowering
was seen in the two populations until early January 2014, when the plant
produced a few flower buds which did not open. However, after a gap of five
months, following the first summer shower in May, the flowers opened. After
critical studies of the specimens, they were referred to Dr. S.E. Dawson, Rubiaceae systematics, Herbarium Royal Botanic Gardens,
Kew, and confirmed the identity as Discospermum
sphaerocarpum, and commented “it is very
interesting that it comes from such a different habitat” (Sally Dawson pers.
comm. 13.vi.2014). The aforementioned pattern of flowering was repeated
in the year 2023 as well. The present paper aims to provide a detailed
taxonomy, distribution and conservation status, illustration and photographic
images of D. sphaerocarpum, for future
reference and conservation.
MATERIALS AND METHODS
The present account of the
species Discospermum sphaerocarpum
is based on two populations; one growing in a sacred grove associated with Madayikkavu Thiruvarkkattu Bhagavathi temple and another one in an undisturbed patch
of vegetation in a private land near Sree Chalilkkavu Bhagavathi temple
(Image 1A,B). The current location is in the
northernmost of Kerala, in Madayippara lateritic
plateau in the Kannur district, which has a completely different habitat not
far separated from the sea coast. Madayippara is one
of the most remarkable midland lateritic plateaus in Kerala (Pramod &
Pradeep 2020) located in Madayi Panchayath, near Payangadi town, Kannur district, between 12.017–12.050 0N
and 75.233–75.267 0E, at an altitude of about 50 m and
extending an area of 3.65 km2 on the top (Pramod & Pradeep
2021).
Madayikkavu sacred grove covers an area of
about 0.4 ha (Image 1A) with a number of rare and endemic species. A
population of Discospermum spaerocarpum of seven trees with heights ranging from 5
m–15 m, and 37 saplings was recorded in this location, covering an area of
about 0.0014 km2 between 12.033358–12.033374 0N and
75.25018–75.250185 0E. The second population is about 200 m away from
Madayikkavu sacred grove, in an undisturbed patch of
vegetation in a private-owned land close to Chalilkavu
Bhagavathi temple (Image 1B). The population consists
of 11 trees ranging in height from 4–20 m, and 15 saplings, covering an area of
about 0.0011 km2, between 12.033386–12.03339 0N and
75.250229–75.250238 0E.
Plant materials were collected
from the two populations available at Madayippara
lateritic plateau for laboratory studies and preparation of voucher specimens.
The specimens collected for laboratory studies were worked out using LEICA M80,
ZEISS Stemi DV4 and LABOMED CSM2 microscopes.
Photographs of the plant specimens and habitats were taken using Nikon Coolpix
L110 and Olympus C-7070 cameras. The voucher specimens were prepared following
wet method (Fosberg & Sachet 1965) and are
deposited at the Calicut University Herbarium (CALI). The distribution status
was determined from ‘Plants of the World Online’ (POWO), pertinent floras and
literature; and the distribution map was created using QGIS ver. 3.28.2 (QGIS
2022).
RESULTS AND DISCUSSION
Taxonomic Treatment
Discospermum sphaerocarpum Dalzell ex Hook.f.
in Thwaites, Enum. Pl. Zeyl.
158. 1859; Dassan., A Revised Handbook to the Fl.
Ceylon 12: 187. 1998; Pramod & Pradeep, A Hillock of Biod.
Fl. Madayippara 442. 2020. Diplospora
sphaerocarpa (Dalzell ex Hook.f.)
Hook.f., Fl. Brit. India 3: 123. 1880; Theodore
Cooke, Fl. Bombay 2: 32. 1958. Tricalysia sphaerocarpa (Dalzell ex Hook.f.)
Gamble, Fl. Madras 620. 1921; R.S. Rao, Fl. Goa, Diu, Daman, Dadra & Nagarhaveli 2: 216. 1986; A.N. Henry et al., Fl. Tamil
Nadu, India, 1987; Sasidh., Biod.
Doc. Kerala 6. Fl. Pl. 237. 2004.
Lectotype: India, Maharashtra, Bombay,
Dalzell, s.n., K000031320 (K, image! ).
Discospermum dalzellii Thwaites, Enum.
Pl. Zey. 15: 158. 1859. Diplospora
dalzellii (Thwaites) Hook.f.,
Fl. Brit. India 3: 123. 1880. Tricalysia Dalzellii (Thwaites) Alston in Trimen,
Hand-Book. Fl. Ceylon (Suppl. 6.) 151. 1931.
Lectotype: Sri Lanka, Thwaites
G.H.K., C.P. 561 (K000031319, K, image!). (Image 1; Figure 2).
Medium-sized trees, up to 20 m
tall; bark greyish-brown, smooth; branches terete, compressed towards the
apices, glabrous. Leaves simple, opposite, elliptic, 8–15 x 3–6 cm, margins
entire, base acute, apex acute-acuminate, glabrous on both sides except domatia, sub-coriaceous, shining above; lateral veins 8–12
pairs, mostly with pubescent domatia in the vein
axils beneath; stipules interpetiolar, triangular, aristate, glabrous; petiole
1–1.5 cm long, glabrous. Inflorescence axillary, mostly in the axils of fallen
leaves, very short branched fascicled cymes, peduncle short; bracts a pair,
ovate, c. 1 mm long, puberulous outside; bracteole 1,
oblong, c. 2 mm long, glabrous. Flowers subsessile,
c. 5 mm long; calyx cupular, c. 1.5 mm long, lobes 4,
subequal, ovate, ciliate, obtuse or shortly retuse at
apex, green; tube short; corolla yellowish green, glabrous outside; tube c. 2
mm long, hairy inside; lobes 4, elliptic-oblong, c. 2 mm long, apically
notched; stamens 4, filaments short, attached at corolla throat, anthers 1.5–2
mm long; ovary subglobose, ovules many; style c. 2 mm
long, glabrous, forked at the apex. Berry subglobose
to obovoid, 1–1.5 cm long; calyx persistent forming a crown at the apex of
fruit; seeds 8–12, immersed in the well-developed placenta, flat, compressed,
reniform, 4–6 × 3–4 mm.
Vernacular names: English: Wild coffee, Tamil: Irrukulimaram, Kannada: Kaadu kafi bija. Sri Lanka: Vella.
Phenology: Since 2008, flowering in this
species was observed only twice, in the year 2014 and 2023. The buds appeared
in early January, and remained dormant till the middle
of May (until heavy summer shower), and the fruits were seen till July.
Distribution and Ecology: The species is endemic to the
Western Ghats and Sri Lanka. However, its recent reports from Philippines (Biag & Alejandro 2021) and Bangladesh (Uddin et al. 2023)
are doubtful, as its description or voucher specimens were not available for
confirmation. In southern India, the species was recorded from the low altitude
to high range (50–1,000 m) evergreen forests of the southern Western Ghats
(Figure 1) (Gamble 1921; Singh et al. 2015 ). In Sri
Lanka, populations were reported from the dry zone at low altitudes in
secondary and rocky areas (Dassanayake 1998). The
trees of the population of Discospermum sphaerocarpum present in the Madayikkavu
sacred grove were seen growing associated with other species such as Aglaia elaeagnoidea (A.Juss.)
Benth., Vitex altissima
L.f., Canthium coromandelicum (Burm.f.)
Alston, Falconeria insignis Royle, Hugonia mystax L., Tinospora
sinensis (Lour.) Merr., Cissus latifolia Lam., Tabernaemontana
alternifolia L., Schleichera oleosa (Lour.) Oken, Benkara malabarica (Lam.) Tirveng.,
Getonia floribunda Roxb.,
Glycosmis mauritiana (Lam.) Tanaka, Sapindus trifoliatus
L., Diospyros candolleana Wight, Memecylon randerianum
S.M.Almeida & M.R.Almeida, Strychnos nux-vomica L., Dalbergia
horrida (Dennst.) Mabb. var. horrida, Alstonia scholaris
(L.) R.Br., Croton caudatus Geiseler, Grewia nervosa
(Lour.) Panigrahi and Bridelia stipularis
(L.) Blume.
Similarly, the trees of the
population of the species seen in the vegetation patch near Chalilkavu
Bhagavathi temple are growing associated with other
species such as Tectona grandis
L.f., Diospyros candolleana
Wight, Strychnos nux-vomica
L., Glycosmis pentaphylla (Retz.) DC., Glycosmis mauritiana
(Lam.) Tanaka, Mallotus philippensis
(Lam.) Müll.-Arg., Tabernaemontana
alternifolia L., Bombax ceiba L., Caryota
urens L., Spondias
pinnata (L.f.) Kurz, Holoptelea
integrifolia (Roxb.) Planch., Ixora malabarica (Dennst.) Mabb., Zingiber zerumbet (L.) Roscoe ex Sm., Gomphia serrata (Gaertn.) Kanis, Ixora brachiata Roxb., Mangifera indica L., Grewia nervosa (Lour.) Panigrahi, Mitragyna parvifolia (Roxb.) Korth., Macaranga peltata (Roxb.)
Müll.-Arg., Chrysophyllum cainito
L., Alstonia scholaris
(L.) R.Br. and Chassalia
curviflora var. ophioxyloides (Wall.) Deb & B.Krishna.
Specimens examined: India, Kerala, Kannur district, Madayippara, Madayikkavu, 16.i.2011, C. Pramod
133024; 17.i.2014, C. Pramod 138241; 28.iv.2014, C. Pramod 138276; near Chalilkkavu, 28.iv.2014, C. Pramod
138277; 14.v.2014, C. Pramod 138287; 04.vi.2014, C. Pramod 138293 (CALI [CALI129230, CALI129231, CALI129232,
CALI129233, CALI129234, CALI129235, CALI129236, CALI129237, CALI129238,
CALI129239, CALI129240, CALI129241, CALI129242, CALI129243, CALI129244,
CALI129245]).
Economic importance:
The berries
are known as wild coffee; the drink made
from the roasted and powdered
seeds has a coffee flavour. In addition to this,
many alkaloids, astringent, aromatic bodies, fat, sugars
and mineral matter are found in seeds
(Nadkarni 1976). Being a reservoir of phytochemical
components, this plant is used as
a potential drug for the treatment of
a variety of human illnesses such as depression and diabetes, and also effective as a good antioxidant. Wood is used for
making comb.
Conservation: An assessment
of tropical dry evergreen forests of Tamil Nadu, recorded that Discospermum
sphaerocarpum occupies
an area of about 10 km2, has around 500 mature individuals, and is declining at a rate of more than
50% due to the widespread usage of the wood
for making comb. No regular
flowering and seed set was observed
in this species in the current location.
There is a serious risk of
losing the population in the second location mentioned, the habitat is on a private-owned land, and
will be cleared off for construction purposes (Image 1B). Discospermum
appears to be at a lower level of evolution than
Diplospora and Tricalysia due to its large, dry fruits, frequent well-developed placental extension around the seeds,
and radial exotestal cell-thickenings (Ali & Robbrecht
1991). These factors necessitate
urgent measures for the conservation of the species
and their habitats. In vitro propagation
will be useful for the conservation
and sustainable utilization of this species.
For figures & images - - click here for full
PDF
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