ted on rocks, show sympodial branching and bear short petiole,
glabrous, narrow leaves with entire margins (van Steenis 1981,
1987). Ixora yunna- nensis Hutch. was first described by Hutchinson
(1916) based on a collection made by Dr. Augus- tine Henry
(1857–1930) from the banks of the Red River (Hong He) in Yunnan
Province, China. Until now, it was considered to be endemic to
Yunnan Province (Chen & Taylor 2011).
During field explorations (2016–2018) in the Koka, Panimur, Amreng
and Zirikindeng regions of West Karbi Anglong District of Assam,
the se- nior author found a rheophytic shrub in rock crevices at
the edge of the Kopili River near Koka. After examining specimens
and consult- ing the literature we identified the plant as Ixora
yunnanensis, a new addition to the Rubiaceae of India and an
extension of its range ca. 760 km westward. A description of the
plant (based on Indian materials) along with photographs and a
distribution map are provided to facilitate future
identifications.
Ixora yunnanensis Hutch. in Sargent, Pl. Wil- son. 3(2): 412
(1916); T. Chen & C. M. Taylor, Fl.
Ixora L. (Rubiaceae), comprising about 530 species of shrubs and
trees (Davis et al. 2009), is the third largest genus in the
family. It is wide- spread in tropical Africa, America, Asia, Mada-
gascar, and the Pacific islands (Chen & Taylor 2011, De Block
2014). Ixora is easily recognized by its articulate petioles,
trichotomously branched terminal inflorescences, narrowly tubular
4-mer- ous flowers with contorted aestivation, 2–4-lobed stigma,
2–4-locular ovary with a single ovule per locule, drupaceous fruits
and seeds with a large adaxial excavation (De Block 1998). In
India, the genus is represented by ca. 50 species (Hooker 1880,
Bremekamp 1937, 1938, 1959, Husain & Paul 1986, 1989, 1991,
Sivadasan & Mohanan 1991, Deb & Rout 1992a, b, Pradeep
1997, Barb- huiya et al. 2012, Murugan & Prabhu 2014,
Karthigeyan & Arisdason 2015, Balan & Shan- mugam 2016).
Chowdhury (2005) listed 8 species from Assam.
Rheophytes are plants that are confined to the bed of swift-running
streams and rivers and grow up to the high water level, but not
beyond the reach of regularly occurring flash floods. Rheo- phytic
land plants are either herbs or shrubs. Shrubby rheophytes usually
have their roots mat-
Acta Phytotax. Geobot. 70 (1): 57–61 (2019)
shorT CoMMuniCaTion
First Record of a Rheophytic Species of Ixora (Rubiaceae) in
India
jaTindra sarMa1, hussain ahMed barbhuiYa2,* and sanTanu deY3
1Research, Education and Working Plans, Assam Forest Department,
Aranya Bhawan, Panjabari, Guwahati, Assam 781037, India; 2Landscape
and Cosmetic Maintenance Section, Architectural and Structural
Engineering
Division, Bhabha Atomic Research Centre, Trombay, Mumbai,
Maharashtra-400085, India. *
[email protected] (author for
correspondence); 3Department of Botany, Nagaland University,
Lumami, Nagaland 798627, India
Ixora yunnanensis (Rubiaceae) is recorded for the first time in
India. Previously, it was considered en- demic to Yunnan Province,
China. The present report extends its distribution range ca. 760 km
west- ward. A brief description of the plant along with photographs
and a distribution map are provided to fa- cilitate its unambiguous
identification in the future.
Key words: flora of India, Ixora yunnanensis, new locality,
rheophyte
doi: 10.18942/apg.201816 ISSN 1346-7565
58 Vol. 70Acta Phytotax. Geobot.
Fig. 1. Ixora yunnanensis Hutch. A, Habit. B, Close up of
inflorescence. C, Late inflorescence showing calyx. D, Twig of
plant with inflorescence. E, Single flower. F, Top view of flower
showing corolla lobes and bearded throat of corolla tube. G, Apex
of flower showing corolla lobes and stigma. H, Inflorescence. All
based on J. Sarma s.n. (HBARC).
February 2019 59sarMa & al–First record of lxora in lndia
China 19: 182 (2011) ––Fig. 1
Type: CHINA. Yunnan, Hsin-Kei (XinKai), Red Riv- er, A. Henry 9585
(holo- K-000763128 image!; iso- NY- 00131977 image!); Red River
banks, Manpan, A. Henry 10370 (para- K-000763129 image!).
Additional specimens examined. INDIA. Assam, West Karbi Anglong,
Panimur, Koka, on the edges of Ko- pili riverbed, 25°4409.91″ N,
92°4915.1″E, 81.59 m msl, 8 May 2017, J. Sarma s.n.
(HBARC-00006395, 00006396, 00006397). CHINA. Yunnan, Lüchun,
Huanglianshan, 24 October 1995, S. K. Wu et. al. 222 (KUN-0770434
im- age); Huanglianshan, 30 October 1995, S. K. Wu et. al. 789
(KUN-0770435 image); Hekou Yao Autonomous County, 23 May 1953, K.
H. Cai 1119 (PE-00737441 im- age); Kafang, 25 May 1953, K. H. Cai
1156 (IBSC- 0443331 image).
Shrub, usually 60–70 cm tall. Stems glabrous, sparsely branched.
Leaves opposite; petiole 0.5– 1.6 cm long, glabrous; blade
lanceolate to narrow- ly oblanceolate, 5.5–15 × 0.6–2 cm, glabrous
on both surfaces, base attenuate, apex acute to long acuminate;
lateral veins 10–15 pairs; stipules in- terpetiolar, persistent,
basally united around the stem, triangular to broadly ovate, 3–4 ×
2.9–3.3 mm, adaxially glabrous, abaxially villous with brown
colleters, apex acute or aristate, arista usu- ally 2.5–3 mm long.
Inflorescences terminal, subsessile to short pedunculate,
corymbiform to
congested cymose, ca. 6.5 × 5 cm; peduncle gla- brous, terete, to
1.3 cm long, 1.8–2.2 mm in diam.; bracts narrowly lanceolate, ca. 6
× 0.6 mm, base occasionally 1 or 2 dentate, apex acu- minate.
Flowers sessile to short pedicellate; pedi- cels up to 3 mm long.
Calyx glabrous, turbinate; hypanthium obconical to slightly
cupuliform, 1.7–2 mm long and ca. 1.7 mm wide at mouth; limb deeply
4-lobed; lobes linear-lanceolate, 3–4 × 0.7–1 mm, apex subacute to
acute. Corolla white; tube 20–35 mm long, slightly dilated up-
wards, 1.0–1.5 mm in diam., white bearded at throat; lobes 4,
narrowly elliptic-oblong, 7.5–8.2 × 3.0–3.5 mm, apex obtuse.
Stamens 4, exserted, alternate to corolla lobes; anthers dorsifixed
near base, oblong, 4.2–4.6 × 0.8–1 mm, base slightly cordate, apex
acute; filament 1.3–1.5 mm long, glabrous, basally adnate to throat
of corolla tube. Ovary glabrous, 2-locular, 1.4–1.6 mm in diam.;
style ca. 36 mm long, exserted from corolla tube; stigma slightly
fusiform, apex bilobed, lobes un- equal, ca. 2.2 mm long. Fruits
and seeds not seen.
Flowering. April–May.
Ecology and Habitat. Ixora yunnanensis is a rheophyte among rocks
at the edges of rivers 80–
Fig. 2. Distribution map of Ixora yunnanensis Hutch. Square ()
indicates previously known localities; solid circle () indi- cates
currently reported locality. Map was created with SimpleMappr,
http://www.simplemappr.net (Shorthouse 2010).
60 Vol. 70Acta Phytotax. Geobot.
102 m above sea level in Koka, Assam, India, where it grows near
fast flowing water. The leaves of Ixora yunnanensis shows typical
characteris- tics of a rheophyte; short petiole, glabrous and
narrow leaf blades with entire margins. Associ- ated rheophytes are
Syzygium cyanophyllum, S. polypetalum (Myrtaceae), Carissa sp.
(Apocyna- ceae), Eriobotrya angustissima (Rosaceae), Pa- vetta sp.
and Tarenna pumila (Rubiaceae).
Distribution. India (Assam: West Karbi An- glong-Koka, present
record), China (Yunnan: Along Red River Banks, Hsin-Kei (XinKai),
Manpan, Lüchun, Mt. Huanglianshan, Hekou Yao Autonomous County,
Kafang, Xishuangban- na, Mengla) (Hutchinson 1916, CVH 2018) (Fig.
2).
Taxonomic note. Ixora yunnanensis can be easily distinguished from
other species of Ixora by its extremely narrow oblanceolate leaves
and longer calyx lobes. It is similar to I. subsessilis Wall. ex G.
Don of India, China and Thailand in having subsessile
inflorescences, but I. subsessi- lis is distinct from I.
yunnanensis in having ellip- tic-lanceolate leaves up to 8.3 cm
wide, shorter triangular calyx lobes up to 2 mm long and a gla-
brous corolla tube. Moreover, I. subsessilis is more vigorous than
I. yunnanensis. Ixora subses- silis usually grows on hill slopes
between 60 and 1,800 m above sea level and is either a shrub or a
small tree up to 2.4 m tall (Husain & Paul 1989). Ixora
yunnanensis in India varies slightly from the plants in China in
having only opposite leaves that are slightly shorter and narrower,
i.e. up to 15 cm long and 2 cm wide. The leaves of Chinese plants
are sometimes ternate and up to 22 cm long and 4 cm wide (Chen
& Taylor 2011).
We thank the Assam Forest Department for allowing us to use their
resources during extensive field exploration, especially in remote
areas. We extend our sincere thanks to Karbi Anglong Autonomous
Council Authority and Hamren Territorial Division for providing
logistical sup- port during fieldwork. We express our heartiest
thanks to the officers and staff of the Southern Range Kheroni,
Hamren Territorial Division, for their continuous assis- tance in
frequent field explorations. Finally, yet impor-
tantly, we are indebted to two anonymous reviewers for their
constructive comments on the manuscript.
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Received July 17, 2018; accepted August 22, 2018