Bangladesh J. Plant Taxon. 31(1): 57-71, 2024 (June) DOI: https://doi.org/10.3329/bjpt.v29i2.74389 © 2024 Bangladesh Association of Plant Taxonomists A TAXONOMIC REVISION OF AXONOPUS P. BEAUV. (POACEAE: PANICOIDEAE) IN INDIA SUPARNA SAHA1, MANASI MANDAL2, SREYOSHEE SENSARMA3, SUBHASMIT BHATTACHARYYA4, DURGA KUMAR PRADHAN5 AND DEBABRATA MAITY1* 1Taxonomy and Biosystematics Laboratory, Department of Botany, University of Calcutta, Kolkata 700 019, West Bengal, India 2Department of Botany, Sundarban Hazi Desarat College, Pathankhali 743611, West Bengal 3Eastern Regional Centre, Botanical Survey of India, Shillong, Meghalaya793003 4Botanical Survey of India, Northern Regional Centre,192 Kaulagarh Road, Dehra Dun 248 195, India 5Quality Control Laboratory-HARC-Sikkim State Forest Herbarium (SSFH), Forests and Environment Department, Government of Sikkim, Gangtok 737102, India Keywords: Axonopus; Eastern Himalaya; Revision; Paspaleae; Poaceae. Abstract The status of the genus Axonopus P.Beauv. in India has been varyingly depicted by different workers so far. After comprehensive study, two species, namely A. compressus (Sw.) P. Beauv. and A. fissifolius (Raddi) Kuhlm., are justified for the country. The distributional incongruity of both species in India is unravelled here. The present record of A. fissifolius in Sikkim confirms its extended distribution to the Indian Eastern Himalaya. Additionally, this species is also reported for the first time from Meghalaya. Detailed descriptions of both species are appended here. Illustrations and photoplates, along with notes on habitat, phenology, and distribution, are also presented. A key to the Indian species of Axonopus is incorporated for correct identification and easy recognition. Introduction The American genus Axonopus P.Beauv. of grass tribe Paspaleae (subfamily Panicoideae, family Poaceae) (Kellogg, 2015; Soreng et al., 2015, 2017) includes approximately 78 species globally (POWO 2024). The members of the genus are mainly found in Tropical Africa, Central U.S.A. to Tropical and Subtropical America and Easter Island, with some species seemingly introduced in the Old World (Chen and Phillips, 2006; Giraldo-Cañas, 2008; Mabberlay, 2017; POWO, 2024; WFO, 2024). The genus has great economic importance as fodder (viz., A. fissifolius (Raddi) Kuhlm., A. obtusifolius (Raddi) Chase, A. purpusii (Mez) Chase, A. scoparius (Flüggé) Kuhlm., A. suffultus (Mikan ex Trin.) Parodi) as well as ornamentals (viz., A. aureus P. Beauv., A. brasiliensis (Spreng.) Kuhlm., A. compressus (Sw.) P. Beauv.) (Black, 1963; Nicora and Rúgolo de Agrasar, 1987; Giulietti et al., 1988). Apparently though the genus looks like Digitaria Haller or Paspalum L. due to almost similar appearance of synflorescence, however, the following combination of characters: 2–many mostly sub-digitately arranged slender racemes, sometimes spread along a short central axis, solitary, adaxial, subsessile, unawned spikelets alternately arranged in 2 rows in each raceme, total absence of lower glume and lower palea and crustaceous upper floret, immediately make the genus distinct from these two allied genera as well as from other related genera of the tribe (Noltie, 2000). The monophyly of Axonopus is strongly recommended by López and Morrone (2012) and Delfini et al. (2020). They advocated inclusion of Centrochloa Swallen and Ophiochloa Filg., *Corresponding author, E-mail: debmaity@yahoo.com https://doi.org/10.3329/bjpt.v29i2.74389 mailto:debmaity@yahoo.com 58 SAHA et al. Davidse & Zuloaga within the generic circumscription of Axonopus, supported by both morphological and molecular evidences. Gledhill (1964) discussed the origin and taxonomy of the West African representatives of Axonopus. The genus in Europe was first revised by Diego Giraldo-Cañas (2008) and five new synonyms were proposed for Axonopus compressus (Sw.) P. Beauv. and A. scoparius (Flüggé) Kuhlm. Cytogenetic and evolutionary relationships in the genus Axonopus were illustrated by Hickenbick (1975). The suitability of Axonopus compressus for the removal of petroleum hydrocarbons from contaminated soil was assessed by Bordoloi et al. (2012). Ibeh and Ezeaja (2011) studied the antidiabetic activity of methanolic leaf extract of Axonopus compressus in alloxan-induced diabetic rats. The genus is variously interpreted by different researchers in terms of number of species in India resulting in confusion. Besides, regional distribution in the country (state wise) differs substantially in different literature. While surveying the grass flora of North Sikkim, few notable specimens of Axonopus were collected from Chungthang and Lachen. After critical examination of the collected materials and perusal of relevant literature (Noltie, 2000; Chen and Phillips, 2006), these were identified as A. fissifolius (Raddi) Kuhlm. This discovery constitutes the first instance of this species in the Indian Eastern Himalaya. In addition, during the present investigation two specimens of the genus collected from Shillong, Meghalaya were located at CAL (Deka 18394; identified as A. compressus) and ASSAM (Rup Chand 8195; identified as A. fissifolius). Both the specimens were reexamined and meticulous observation revealed that Rup Chand 8195 was rightly identified as A. fissifolius, while Deka 18394 also appears to be A. fissifolius. This finding validates the species' wider distributional range, extending to Meghalaya, the second state in Northeast India after Assam. Besides, though several workers (Naithani and Raizada, 1977; Naithani, 1990; Shukla, 1996; Kellogg et al., 2020) claimed this species for Uttar Pradesh, however, it is now excluded from the flora of the state with evidence. On the contrary, report of this species from Uttarakhand is accepted with justification. In this communication, a revision of Axonopus in India is presented based on field observation as well as study of the herbarium specimens. In addition, we illustrate the current distribution of both species in the country. The new distributional records of A. fissifolius are elucidated with evidence. The elaborate morphological descriptions of both members, along with detailed citations and type information, are incorporated herewith for better taxonomic understanding. Hand drawings and photo plates are also included for easy recognition and correct identification. Habitat information, phenological data, exsiccate and key to the Indian species of the genus are also provided. Materials and Methods Rigorous field surveys have been conducted during 2021-2024 in different parts of India and a considerable number of specimens of Axonopus were collected. During collection, all relevant field data have been recorded to understand the morphological attributes of the members of the genus and also to observe the variation and variability of morphological features between the populations and even within the population, if any. The characters which are widely used in segregating species as discussed earlier have been critically encountered in the field itself. Digital photographs have been captured. Specimens were collected at least in triplicates from each population. To ascertain the taxonomy and distribution of both the members of the genus in India, collections of Axonopus housed at ARUN, ASSAM, BSA, BSD, BSID, BSHC, CUH, CAL, DD, MH, PBL and TBGT were rigorously studied. Relevant literature were also consulted. The A TAXONOMIC REVISION OF AXONOPUS P. BEAUV. (POACEAE: PANICOIDEAE) 59 identity of both the species was confirmed after having an eye to the protologues and matching with the type specimens or digital images of the types as well as with other authentic specimens available at JSTOR and other online herbarium databases. Voucher specimens are deposited at CUH for future reference. Results and Discussion Taxonomic Treatment Axonopus P. Beauv., Ess. Agrostogr. 12.1812; Hooker, J. D. in Hooker, J. D., Fl. Brit. India 7:63.1896; Prain, Bengal Pl. 2:1173.1903 (Rep. 1963); Bor, Fl. Assam 5:268.1940 et Grass. Burma Ceylon India Pakistan 277.1960; Shukla, Grass. North-Eastern India 308.1996; Noltie, Fl. Bhutan 3(2): 716.2000; Bhat and Nagendran, Sedge. Garss. 182.2001; Chen and Phillips in Wu et al., Fl. China 22:530.2006; Kabeer and Nair, Fl. Tamil Nadu Grass. 213.2009; Potdar et al., Grass. Maharashtra 301.2012; Sur and Roy Choudhury, Grass. Fl. West Bengal, India 92.2015; Sinha et al., Pl. Indian Himal. Reg. Annot. Checkl. Pict. Guid. 2:786.2019; Veldkamp et al. in Middleton et al., Fl. Singapore 7:262.2019; Prasanna et al. in Mao and Dash, Flower. Pl. India Annot. Checkl. Monocot. 3:326.2020; Kellogg et al., Checkl. Grass. India 207.2020; Siddabathula and Prasanna, Grass. Telengana 170.2023. Lectotype: Axonopus compressus (Sw.) P. Beauv. (≡Milium compressum Sw.). LT designated by Hitchcock in Contr. U.S. Natl. Herb. 12: 142. 1908; Chase, Proc. Biol. Soc. Wash. 24: 129. 1911. Stoloniferous perennials (rarely annuals); stolons spreading, compressed. Culms short, erect, single-noded. Leaves sub-basal; leaf blades flat or involute, oblong, blunt or obtuse; ligule short, membranous, truncate, ciliolate; leaf sheaths compressed, keeled. Synflorescence of 2–many slender racemes, mostly sub-digitate, sometimes along a short central axis; racemes linear, spikelets borne singly, alternate on opposite sides of the triquetrous rachis. Spikelets sessile or subsessile, lanceolate to oblong, flatly biconvex, adaxial, compressed, unawned, muticous, falling entire. Glume solitary; lower glume absent; upper glume facing away from rachis, back flat, 2–7- veined with 1–3 marginal veins on either side, midvein faint or absent, membranous. Florets 2; lower floret sterile, epaleate; lower lemma similar to and about equaling upper glume; upper floret bisexual, compressed; upper lemma crustaceous to coriaceous, back flat, punctate, margins opaque and incurved, tightly enclosing the palea; upper palea flat-backed, crustaceous. Lodicules 2. Stamens 3. Pistil 1; style 2, free; stigmas plumose, exserted laterally. Caryopsis elliptic, dorsally compressed, totally enclosed by indurate upper palea and lemma. Distribution: The native range of this genus is Tropical Africa, Central U.S.A. to Tropical & Subtropical America and Easter Island, with some species seemingly introduced in Africa, Asia- Temperate, Asia-Tropical, Australasia, Europe, Northern America and Pacific (Chen and Phillips, 2006; Giraldo-Cañas, 2008; Mabberlay, 2017; POWO, 2024; WFO, 2024). Axonopus compressus (Sw.) P. Beauv., Ess. Agrost. 12, 154, 167.1812; Bor, Fl. Assam 5:269.1940 et Grass. Burma Ceylon India Pakistan 278.1960; Hara, Fl. Eastern Himal. 352.1966; Shukla, Grass. North-Eastern India 310.1996; Noltie, Fl. Bhutan 3(2):717.2000; Bhat and Nagendran, Sedge. Garss. 182.2001; Chen and Phillips in Wu et al., Fl. China 22:531.2006; Kabeer and Nair, Fl. Tamil Nadu Grass. 213.2009; Potdar et al., Grass. Maharashtra 301.2012; Sur and Roy Choudhury, Grass. Fl. West Bengal, India 92.2015; Sinha et al., Pl. Indian Himal. Reg. Annot. Checkl. Pict. Guid. 2:786. 2019; Veldkamp et al. in Middleton et al., Fl. Singapore 7:262.2019; Prasanna et al. in Mao and Dash, Fl. Pl. India Annot. Checkl. Monocot. 3:326.2020; 60 SAHA et al. Kellogg et al., Checkl. Grass. India 208.2020; Siddabathula and Prasanna, Grass. Telengana 170.2023. Milium compressum Sw., Prodr. 24. 1788. Lectotype: Jamaica, R. Shakespear s.n. (BM [BM000578790, digital image seen], designated by Pohl & Davidse, Fl. Mesoamer. 6: 357.1991). Paspalum compressum (Sw.) Raspail (1825), nom. illeg.; P. tristachyon Lam. (1791) {Type: “Ex America merid. Communic. D. Richard.” South America; L.C.M. Richard s.n. (P-LAM, not seen; BAA, BAA00002565, digital image seen; US, US00140865, digital image seen)}; P. platicaulon Poir. (1804) [as “platycaule” in IPNI]; Digitaria platicaulis (Poir) Desv. (1831); Panicum platicaulon (Poir.) Kuntze (1898) (as “Platycaulon”); Anastrophus platycaulis (Poir.) Nash (1903) {Type: “Cette espece a été recueillie a Porto Ricco, par le citoyen Ledru.” Puerto Rico; A.P. Ledrú s.n. (P-LAM, not seen; US, US00140744 & US00140745, digital images seen)}; Paspalum platyculmum Thouars ex Nees (1829) {Type: “Habitat in insula S. Mauritii.”(not seen)}; P. depressum Steud. (1853) {Type: USA: Louisiana; F.X.von Hartmann 51 (P, P00753081, digital image seen)}; P. filostachyum A. Rich. ex Steud. (1853) {Type: West Indies; F.W. Sieber 365 (P, not seen; US, US00140655, digital image seen)}; P. guadaloupense Steud. (1853) {Type: Guadeloupe; Duchaissing s.n. (P, not seen)}; P. raunkiaerii Mez. (1917) {Type: Antillarum insula St. Jan; Raunkiaer 1313 (US, US00140795, digital image seen; C, C10016782, digital image seen)}; P. laticulmum Spreng. (1824; “1825”), nom. superfl. & illeg. for P. tristachyon; Agrostis compressa (Sw.) Poir. (1810), non Axonopus compressa Willd.1790; Digitaria domingensis Desv. ex Kunth.1833, non Roem. & Schult. (1817); Anastrophus compressus sensu Schltr. ex Döll. (1877), nonb Schltdl. (1850). (Figs 2 & 3) Perennial. Culms creeping or stoloniferous, sometimes mat forming, erect while flowering, 15–32 cm tall, terete; nodes bearded, brownish, lower ones rooting. Leaf blades broadly linear or lanceolate, 5–20 × 0.6–1.2 cm, apex obtuse, margin ciliate, otherwise glabrous or adaxial surface pilose; ligule 0.8–1 mm long, membranous, truncate, apex finely fimbriate, base narrowed; leaf sheaths 2.5–8 cm long, margins usually sparsely tuberculate hairy. Spikelets arranged in terminal racemes; racemes 3, digitate or sub-digitate, 5.5–9 cm long; peduncles ca. 6 cm long, short, enclosed by sheath; rachis triquetrous, ca. 0.5 mm wide, margin winged, serrulate; spikelets sub- sessile, in 2-rows, alternate, linear-oblong, 2–3 × 0.65–1 mm, acute or acuminate, shaggy hairy; pedicels 0.4–1.5 mm, flat. Glume 1; lower glume absent; upper glume elliptic, oblong or oblong- lanceolate, 2–2.5 × 0.4–1 mm, acute to acuminate and never overtopped by hairs, chartaceous, flat, appressed hairs forming a line on both sides of mid-vein, 5-veined, appressed-hairy on veins, margins incurved with long, woolly hairs below. Florets 2, lower sterile and upper bisexual; lower lemma elliptic or oblong-lanceolate, 1.7–3 × 0.5–0.9 mm, acuminate to apiculate, flat, appressed hairs forming a line on both sides of mid-vein, 5-veined, appressed-hairy on veins, margins incurved; lower palea absent; upper lemma elliptic-lanceolate, 1.3–2.5 × 0.4–1 mm, apex blunt to acute with tuft of cilia, margin tightly enclosing palea, sub-coriaceous to crustaceous, faintly 3- veined, pale green; upper palea oblong or elliptic, 1.4–2.5 × 0.5–0.8 mm, acute or obtuse, margin inrolled, sub-coriaceous to crustaceous, faintly 2-veined, pale green. Lodicules 2, 0.2–0.4 × 0.2– 0.3 mm, membranous, hyaline. Stamens 3; filaments 0.3–0.5 mm long; anthers 0.6–1.2 × ca. 0.2 mm, yellowish to purplish. Pistil 1: ovary oblongoid-ellipsoid, 0.3–1 mm long; styles 2, straight, 0.5–1.3 mm; stigmas 2, 0.8–1.5 mm, plumose, yellowish to brownish. Caryopsis oblongoid, 1–2 × ca. 0.6 mm, flat, greenish. Flowering and fruiting: Almost throughout the year A TAXONOMIC REVISION OF AXONOPUS P. BEAUV. (POACEAE: PANICOIDEAE) 61 Habitat: Prefer to grow in open forest margins, as weed along roadsides, in waste ground, neglected garden and orchards in association with Digitaria ciliaris (Retz.) Koeler (Poaceae), Paspalum conjugatum Bergius (Poaceae), etc. Distribution: INDIA: Andaman & Nicobar Islands, Andhra Pradesh, Arunachal Pradesh, Assam, Bihar, Chhattisgarh, Himachal Pradesh, Jharkhand, Karnataka, Kerala, Madhya Pradesh, Maharashtra, Meghalaya, Odisha, Sikkim, Tamil Nadu, Telengana, Uttarakhand, Uttar Pradesh, West Bengal. Native to Tropical and Subtropical America; introduced and naturalized in Africa, Asia-Temperate, Asia-Tropical, Australasia, Europe, Northern America, Pacific (POWO, 2024; WFO, 2024). [up to 2300 m amsl] Specimens examined: Andaman & Nicobar Islands, Rangat, 46 m, 15.10.59, Thampi H.C. 5 (CAL); Little Andaman, Hut Bay, sea level, 20.11.1977, Bhargava 6523; Great Nicobar, 35 Km North & South Road to Galasthea river, 23 m, 25.05.2012, Prabhu & Sathiyaseelan 0753 (all at PBL). Andhra Pradesh, towards Chinthim from Maredumilli, ±550 m, 16-10-94, M. Mohanan 102514 (MH). Assam, Lakhimpur, Tinsukia, July-1937, N.L.Bor s.n. (DD); Digboi Forest Bunglow Compound, 10.07.1959, Panigrahi 18950 & 18951 (CAL); Bokajan, 25.01.74, Neogi 56914; Kamrup, G.U. Campus, 1132 m, 09.05.74, Neogi 57022; Manas, Mathnguri, 07.06.74, Neogi 57072; Borail, WLS, near Kalainchurra, 27.08.2012, Barbhuiya 930; Bhutto Bagan, 50 m, 29.08.2013, Deori & Tahakdu 115421(all at ASSAM); Duhalia R.F., 20.04.2014, Moonmee Devi 12379 (ASSAM, CAL). Chhattisgarh, Korba, CG, 10.09.2009, Tiwari 99612 (BSA, two specimens, not seen). Karnataka, Bhadravathi, s.d., A.N.Sindhe 204 (CAL); Subramanya, South Kanara, 500/, 9.2.1952, H Sunanda Kamath 94244 (MH). Kerala, Peermede, Travancore, 3200/, 2.12.1941, without collector’s name, 20223 (MH); Peaty Soils, 3.11.56, B.D.Patil 783; Vazhoor, 04.11.56, B.D.Patil 802; Chandanathode, ±825 m, 24.02.1979, V.S.Ramachandran 61351; Nedumpoyil, ±500 m, 12.12.1979, V.S.Ramachandran 64072; Panathur, 250 m, 29.6.1980, R.Ansari 67905; Kurumathur, 250 m, 23.09.1982, R.Ansari 73963; Kumarakom, below 5 m, 28- 12-1983 V.T.Antony 14 (all at CAL); Garden site, 25.10.84, K.C.Koshy 487; Chemingi, Agasthyamala, 18.3.93, N.Moharan 11343; Sultan Battery, Nilgiri Biosphere Reserve, 23.07.2012, Remya. J & Prasanna. R 73707; JNTBGRI, 27.02.2013, K.C.Koshy 70542; VSSC Thuma, 5.2.14, Teema Joseph 85149 (all at TBGT). Madras (Chennai), Ghat, R.F. Coonoor, 1666 m, 27-7-1957, K.M.Sebastine 4054; Arankattumalai, Kakachi, 1733 m, 7-5-1958, K.M.Sebastine 5807; near Kumili, 850 m, 22.06.1959, Subramanyam 8147; Near Periyar Dam, 980 m, 19.10.1959, Subramanyam 9449 (all at CAL). Manipur, Nambol, Bishnupur District, 776 m, 26.10.2013, Dui 11289; Bamonkampu, Imphal East District, 783 m, 02.11.2013, Diu 12012 (all at ASSAM). Meghalaya, Shillong, area infront of Nirala Bunglow, 23.11.1956, Panigrahi 3791 (ASSAM, CAL). Telengana, Rangareddy District, Hyderabad, Lacones SNR s.n. (BSID). Tamil Nadu, Kotagiri, s.d., Sindhe 216; Shembaganur, 6000 ft, Oct 1955, without collector’s name, 47 (all at CAL); Nadugani sholar, Gudalur, ±600-700 m, 21.7.2003, K. Althof Ahamed Kabeer 116248 (MH). Uttarakhand, Bangapani, Gori valley Pithoragarh, 20.09.03, Kandwal 155; Hudki village, Pithoragarh, 26.07.04, Kandwal 3348 (all at BSD). West Bengal, Ballygunj, Calcutta, 13.11.1919, Nuskriji 2; AJC Bose Indian Botanic Garden, near the Big Banyan tree, 14/12/20, P.M.Debbarman s.n.; near Oreodoxa Avenue, 15/12/20, P.M.Debbarman s.n.; near Palm Avenue, 15/12/20, P.M.Debbarman s.n.; near the Herbarium, 15/12/20, P.M.Debbarman s.n. Buxa, Santrabari, 700/, 23.5.49, V.Narayanaswami & Party 2940; IBG, 20th Div., 2.11.1966, Sharma V.S. S-590; Botanic Garden, Howrah, student garden’s sides, 4-12-1967, D.K.Banerjee 4882; West Dinajpur, Ranigunj, 01.11.1983, R.N.Banerjee & M.C.Biswas 16108; West Dinajpur, Islampur, 22.4.1984, R.N.Banerjee & Party 17554; West Dinajpur, Ranigunj, 20.8.1984, R.N.Banerjee & Party 17569 (all at CAL); Howrah, Bokultala, near AJC Bose Indian Botanic 62 SAHA et al. Garden gate, 15 m, 19.11.2018, Saha 16622; Kalimpong, Samsing, Suntalekhola, 99 m, 26.04.2023, Maity, Roy and Halder 21 (all at CUH). Axonopus fissifolius (Raddi) Kuhlm., Relat. Commiss. Linhas Telegr. Estratég. Matto Grosso Amazonas 5(11):87.1922; Chen and Phillips, in Wu et al., Fl. China 22:531.2006; Veldkamp et al. in Middleton et al., Fl. Singapore 7:264.2019; Prasanna et al. in Mao and Dash, Fl. Pl. India Annot. Checkl. Monocot. 3:326.2020; Kellogg et al., Checkl. Grass. India 209.2020. Paspalum fissifolium Raddi, Agrostogr. Bras. 26.1823. Lectotype: Raddi s.n. (PI [PI041257, digital image seen], designated by Judziewicz, Fl. Guianas, ser. A, Phanerogams 8: 98.1990); isolectotypes (BAA [BAA00001538, digital image seen], BM [BM000578791, not seen], FI [FI004592, digital image seen], G [not seen], K [K000643281, digital image seen], US [US00140658, digital image seen], W [W19040012152, digital image seen]). Axonopus affinis Chase (1938); A. compressus var. affinis (Chase) Hend. (1954) {Type: USA: Mississippi: Waynesboro, in low moist ground, 2 Oct. 1896, T.H. Kearney 175 (holotype US [US00139602, digital image seen]; isotypes GH [GH00023151, digital image seen], MO [MO-016675, digital image seen], US [US00139603, digital image seen])}; Paspalum xizangense B.S.Sun & H.Sun (2001) {Type: Medog, Beibeng, 950m, 24 Sep 1992, Sum Hang et al. 0042 (holotype KUN [not seen]; isotype YUNU [not seen])}. (Figs 1, 4 & 5) Stoloniferous perennials, often mat-forming. Culms compressed, 2.5–50 cm tall, nodes glabrous, green to purplish red. Leaf blades broadly linear, folded, 2–20 × 0.2–0.6 cm, obtuse, margin pilose near the base only, otherwise glabrous; upper one (just below the racemes, often known as ‘flag leaf’) always distinctly smaller; ligule membranous, 0.2–0.3 mm, truncate, densely ciliolate at apex and back; leaf sheaths compressed, 1.7–7 cm long, strongly keeled, glabrous. Spikelets arranged in racemes; racemes 2–4, 2-paired, any others spaced slightly below, 3–6 cm long, slightly diverging; rachis glabrous; peduncle long exserted from upper leaf sheath; spikelets oblong-elliptic or ovate-elliptic, 1.5–2.5 × 0.6–0.8 mm, subacute, apex and margins pilose. Glumes 1; lower glume absent; upper glume oblong or ovate, 1.8–2.5 × 0.6–1 mm, blunt to subacute and always overtopped by hairs, flat, margins incurved, 4-veined laterally, mid-vein absent, membranous, appressed-hairy, with long, woolly hairs abaxially and along margins. Floret 2; lower sterile, upper bisexual; lower lemma oblong-lanceolate or elliptic, 1.8–2 × 0.6-0.9 mm, acuminate to apiculate, 2-veined laterally, midvein absent, flat, margins incurved, membranous, appressed-hairy near apex; lower palea absent; upper lemma oblong-elliptic or oblong-ovate, compressed, 1.4–1.7 × 0.7–1 mm, obtuse to blunt, with short apical tuft of cilia, crustaceous, margin membranous, pale; upper palea elliptic, 1.3–1.6 × 0.6–0.8 mm, similar to lemma but glabrous. Lodicules 2, oblong-obovate, 0.2-0.3 × ca. 0.2 mm, membranous. Stamens 3; anthers 0.7–0.8 × 0.2–0.3 mm, yellow, becoming purple at maturity; filaments 0.3–0.4 mm long, hyaline. Pistil 1; ovary 1, oblongoid, 0.3–0.4 × 0.2–0.3 mm; styles 2, 0.4–0.5 mm long; stigmas 2, 0.5–1 mm long, plumose, yellow, becoming purple at maturity. Caryopsis ellipsoid or oblongoid- ellipsoid, 1–1.1 × 0.5–0.6 mm, obtuse, glabrous; hilum obovoid ca. 0.3 mm long. Flowering and fruiting: March-October Habitat: Prefer to grow along the roadside green patches in association with Ageratina adenophora (Spreng.) R.M.King & H.Rob. (Asteraceae), Artemisia vulgaris L. (Asteraceae), Cuphea carthagenensis (Jacq.) J.F.Macbr. (Lythraceae), Galinsoga parviflora Cav. (Asteraceae), Paspalum distichum L. (Poaceae), Thysanolaena latifolia (Roxb. ex Hornem.) Honda (Poaceae), etc. A TAXONOMIC REVISION OF AXONOPUS P. BEAUV. (POACEAE: PANICOIDEAE) 63 Fig. 1. Axonopus fissifolius (Raddi) Kuhlm.: A. Habit; B. Synflorescence; C. A single raceme. 64 SAHA et al. Fig. 2. Axonopus compressus (Sw.) P. Beauv.: A. Spikelet; B. Upper glume (abaxial surface); C. Upper glume (adaxial surface); D. Lower lemma (abaxial surface); E. Lower lemma (adaxial surface); F. Upper lemma (abaxial surface); G. Upper lemma (adaxial surface); H. Upper palea (abaxial surface); I. Upper palea (adaxial surface); J. Lodicules; K. Stamens & pistil; L. Caryopsis A TAXONOMIC REVISION OF AXONOPUS P. BEAUV. (POACEAE: PANICOIDEAE) 65 Fig. 3. Axonopus compressus (Sw.) P. Beauv.: A. Habit; B. Ligule; C. Spikelet; D. Upper glume; E. Lower lemma; F. Upper lemma; G. Upper palea; H. Lodicules; I. Stamens & pistil; J. Caryopsis. Illustrated by Suparna Saha from Saha 16622 & Maity, Roy and Halder 21. 66 SAHA et al. Fig. 4. Axonopus fissifolius (Raddi) Kuhlm.: A. Spikelet; B. Upper glume (abaxial surface); C. Upper glume (adaxial surface); D. Lower lemma (abaxial surface); E. Lower lemma (adaxial surface); F. Upper lemma (abaxial surface); G. Upper lemma (adaxial surface); H. Upper palea (abaxial surface); I. Upper palea (adaxial surface); J. Lodicules; K. Stamens & pistil; L. Stamens & pistil (at maturity); M. Caryopsis A TAXONOMIC REVISION OF AXONOPUS P. BEAUV. (POACEAE: PANICOIDEAE) 67 Fig. 5. Axonopus fissifolius (Raddi) Kuhlm.: A. Habit; B. Ligule; C. Spikelet; D. Upper glume (abaxial surface); E. Upper glume (adaxial surface); F. Lower lemma (abaxial surface); G. Lower lemma (adaxial surface); H. Upper lemma (abaxial surface); I. Upper lemma (adaxial surface); J. Upper palea (abaxial surface); K. Upper palea (adaxial surface); L. Lodicules; M. Stamens & pistil; N. Caryopsis. Illustrated by Suparna Saha from Maity, Mandal, Ghosh, Midday, Saha and Halder 24810. 68 SAHA et al. Distribution: INDIA: Andaman & Nicobar Islands (doubtful), Assam, Meghalaya (present report), Sikkim (present report), Uttarakhand; China, Bhutan, Myanmar, Singapore, Taiwan (Noltie, 2000; Chen and Phillips, 2006; Veldkamp et al., 2019). [1000-2300 m amsl] Specimens examined: Meghalaya, Khasi Hills, 1524 m, s.d., Rupchand 8195 (ASSAM); Shillong, Khasi & Jaintia Hills, 28.8.1959, G.K.Deka 18394 (2 herbartium sheets at CAL). Sikkim, towards Lachen, 2250 m, 12.06.2022, Maity, Mandal, Ghosh, Midday, Saha and Halder 24810; Chungthang to Lachung, 19.08.2023, Maity, Mandal, Ghosh, Saha and Halder 26805; near Munsithang, 19.08.2023, Maity, Mandal, Ghosh, Saha and Halder 26820; Chungthang, 1618 m, 20.08.2023, Maity, Mandal, Ghosh, Saha and Halder 26842; Phodong, 1656 m, 20.08.2023, Maity, Mandal, Ghosh, Saha and Halder 26846 (all at CUH). Key to the Indian species of Axonopus 1. Culm nodes bearded; leaf blades 0.6-1.2 cm across, margin long-ciliate; longest raceme spicate to base; glume apex acute, never overtopped by hairs; upper floret shorter than spikelet A. compressus - Culm nodes glabrous; leaf blades 0.2-0.6 cm across, margin eciliate, pilose near base only; longest raceme espicate at base; glume apex blunt, overtopped by hairs; upper floret equaling spikelet A. fissifolius Note: Many workers claimed only A. compressus (Sw.) P. Beauv. in India (Kabeer and Nair, 2009; Potdar et al., 2012; Sur and Roy Choudhary, 2015), though in the past, Shukla (1996) reported A. fissifolius (Raddi) Kuhlm. from the then Uttar Pradesh and Assam in addition to the former while studying the grasses of North-Eastern India. Recently, Prasanna et al. (2020), Kellogg et al. (2020), and Siddabathula and Prasanna (2023) also listed both species for the country. Likewise, the regional distribution within the nation (state-by-state) also varies significantly. Prasanna et al. (2020) reported A. compressus in 14 states of India, including Jharkhand, Odisha, and Sikkim. On the other hand, Kellogg et al. (2020), though recorded the same species also in these 14 states of India but did not includ Jharkhand, Odisha, and Sikkim. On the contrary, they reported the species in Arunachal Pradesh, Himachal Pradesh, and Uttar Pradesh, which are not mentioned by Prasanna et al. (2020). Notably, Tiwari and Ansari (2014) and Bawistale (2016) recorded A. compressus in Chhattisgarh and Madhya Pradesh, respectively, however, both Prasanna et al. (2020) and Kellogg et al. (2020) did not recognize the species for these two states. Recently, Siddabathula and Prasanna (2023) recorded this species in Telengana. In the case of A. fissifolius, the same contradiction prevails. According to Naithani and Raizada (1977), A. fissifolius was first recorded by R.B. Majumdar, as evident from his note on the herbarium sheet Naithani 1868 (CAL), where he stated that “I have also reported it from Assam, where it is also naturalized. But my report has not yet been published”. However, Naithani and Raizada (1977) published the first evidence on its occurrence in India from Dehra Dun. Later on, Naithani (1990) stated its distribution in Uttar Pradesh. Subsequently, referring to Naithani and Raizada (1977), its distribution in Uttar Pradesh was also reported by Shukla (1996), though no specimen was scrutinized by him. Notably, Uniyal et al. (2007) did not include the genus Axonopus in the checklist of flowering plants in Uttarakhand. On the other hand, while updating the grass flora of Uttarakhand, Kandwal and Gupta (2009) reported only A. compressus for the state. Furthermore, under the present investigation, one specimen collected from Gori Valley region of Uttarakhand and identified as A. affinis (≡A. fissifolius) has been traced at BSD. Though A TAXONOMIC REVISION OF AXONOPUS P. BEAUV. (POACEAE: PANICOIDEAE) 69 it apparently looks like A. fissifolius, in-depth character assessment confirms its identity as A. compressus. Recently, Kellogg et al. (2020) documented this species in Uttar Pradesh based on Naithani (1990). But we failed to trace any representative specimen in any herbaria collected from present day Uttar Pradesh. Notably, Naithani and Raizada (1977) recorded this species in Dehra Dun, the capital of Uttarakhand, and thus the distributional data by Kellogg et al. (2020) is corrected here for this state. Therefore, Uttar Pradesh is excluded from the distributional range of this species, which also corroborates Agnihotri et al. (2023), where the genus Axonopus is not considered under the recent floristic checklist of the state. Prasanna et al. (2020) claimed the distribution of A. fissifolius in Andaman & Nicobar Islands and Assam. But specimens from neither of the states have been traced during this study, hence, the existence of the species in these two states is doubtful. Acknowledgements We are grateful to the Vice Chancellor, University of Calcutta for facilities and support. We are beholden to the University Grants Commission (UGC) and Science & Engineering Research Board (SERB), DST-FIST, DBT-BUILDER, Govt. of India for financial assistance and the Department of Forests, Environment and Wildlife Management, Govt. of Sikkim, Home Department, Govt. of Sikkim, Superintendent of Police, Gangtok and 17th Mtn. Division, Indian Army for permitting and supporting our field visit. Authors are grateful to the Director, Botanical Survey of India, Head of Office, Central National Herbarium (CAL) and In-charge, Sikkim Himalayan Circle (Botanical Survey of India) for giving permission to consult herbarium. Curators of all the herbaria cited in this paper (ASSAM, BSA, BSD, BSHC, CAL, DD, MH, PBL, TBGT) are acknowledged here for making it easy to carry out studies on grasses. We express our gratitude to Dr. B. Ranjan (BSA), Dr. Wilson Arisdason (MH) and Dr. Lalji Singh (PBL) for providing important information on the distribution of the species. 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