Cenchrus brownii Roem. & Schult., Syst. Veg. 2: 258. 1817.

Wessapak, Paweena, Ngernsaengsaruay, Chatchai & Duangjai, Suthee, 2023, A taxonomic revision of Cenchrus L. (Poaceae) in Thailand, with lectotypification of Pennisetum macrostachyum Benth., PhytoKeys 234, pp. 1-33 : 1

1. Cenchrus brownii Roem. & Schult., Syst. Veg. 2: 258. 1817.

Figs 1 , 2

≡ Cenchrus inflexus R. Br., Prodr. Fl. Nov. Holland.: 195. 1810.

= Cenchrus viridis Spreng., Syst. Veg. 1: 301. 1824. Type: West Indies, Guadeloupe, C. G. Bertero s.n. (holotype: B [B100248055] seen on digital image). ≡ Cenchrus echinatus L. var. viridis (Spreng.) Spreng., Fl. Brit. W. I.: 556. 1864.

= Cenchrus hexaflorus Blanco, Fl. Filip.: 36. 1837. Type: Philippines, Manila, Luzon, Feb 1915, E. D. Merrill Sp. Blancoan. 811 (neotype, designated by Merrill 1918, pg. 68: US n.v.; isoneotypes: L n.v., P [P00642071!], W n.v.).

= Cenchrus dactylolepis Steud., Syn. Pl. Glumac. 1: 109. 1854. Type: Surinam, 1843, F. W. R. Hostmann 12a (holotype: P [P00642090!]; isotype: BAA n.v.).

Type.

Australia, Arnheim South Bay , 6 Feb 1803, R. Brown 6140 (lectotype, designated by DeLisle 1963, pg. 280: BM [BM000795713!]; isolectotypes: E [E00381727] seen on digital image, K [K000215260!], P [P00642070!], US (frag.) n.v.).

Description.

Annual, tufted, Culms geniculate ascending, 30-80 cm high; nodes glabrous; internode subterete, 5-13 cm long, 1-3 mm in diam., glabrous. Leaf sheaths 4.5-10 cm long, margins membranous, glabrous. Ligules a fringe of hairs, 0.5-1 mm long. Collar glabrous. Leaf blades linear, 14-38 × 0.6-1 cm, apex acute, base rounded, margins scabrous, chartaceous, usually conduplicate, glabrous on both surfaces. Inflorescence spiciform panicle, 14-43 × 0.8-1.2 cm (including bristles); central axis angular, 5.5-10 cm long, axis internode 0.5-2 mm long, scabrous to glabrescent; peduncle terete, 7-34 cm long, glabrous or scabrous; short racemes crowded along central axis; raceme with (1-)2-3 spikelets in cluster, all sessile, subtended by an involucre of burr-like spines and bristles. Involucre compose of outer and inner circles; outer circle usually longer than inner circle; outer involucre of bristles, numerous and filamentous, free, 1-6 mm long, one conspicuous longest bristle 4.5-9 mm long, retrorsely scabrous; inner involucre of 6-10 flattened spines, 4-5.2 mm long, connate at lower part 1-3 mm long, burr-like forming, a cup up to 5 mm in diam., coriaceous, puberulose and retrorsely scabrous; involucre falling with spikelets; stipe (raceme-based) 1-2 mm long, hairy. Spikelets dorsally compressed, lanceolate, 3.6-5.5 × 1-1.7 mm. Lower glume usually absent, if well-developed, ovate, 0.6-1.2 × 0.3-0.5 mm, apex acute, membranous, glabrous, 1-nerved. Upper glume ovate or lanceolate-ovate, 3-4 × 1.2-1.8 mm, apex acute or acuminate, membranous to chartaceous, glabrous, 3 or 5-nerved. Florets 2. Lower floret male or sterile. Lower lemma lanceolate, 3.5-5 × 1-1.5 mm, apex acute or acuminate, membranous to chartaceous, glabrous, 3 or 5-nerved. Lower palea lanceolate-oblong, 3.2-5 × 0.8-1 mm, apex acute or acuminate, margins folded with antrorsely scabrous, membranous, glabrous, 2-nerved or palea absent. Upper floret bisexual. Upper lemma lanceolate or ovate-lanceolate, 2.5-5 × 1-1.8 mm, apex acute or acuminate, margins hyaline, coriaceous, glabrous, 5-nerved. Upper palea lanceolate, 2.5-5 × 0.9-1.5 mm, apex acuminate, margins hyaline, coriaceous, glabrous, 2-keeled, 2-nerved. Lodicules 2, ca. 0.5 mm long, truncate. Stamens 3; filament ca. 3 mm long; anther yellow 1-1.6 mm long. Pistil ovary elliptic, 0.6-1 × 0.2-0.3 mm; style 2; stigma plumose. Caryopsis obovoid or ellipsoid, gibbous, 1.5-2.5 × 1-1.7 mm.

Distribution.

Native to tropical and subtropical America. Introduced to Southeast Asia and Oceania.

Distribution in Thailand.

NORTHERN: Chiang Mai (Mae Rim, Doi Suthep-Pui, Mueang Chiang Mai), Tak (Wang Chao Forest, Bhumibol Dam), Sukhothai (Sawan Khalok), Kamphaeng Phet (Phran Kratai), Nakhon Sawan; NORTH-EASTERN: Khon Kaen (Chum Phae); EASTERN: Nakhon Ratchasima (Pak Chong), Amnat Charoen; South-Western: Uthai Thani (Khao Phraya Phai Ruea), Kanchanaburi (Sai Yok, Ban Kao), Ratchaburi (Huai Yang), Prachuap Khiri Khun (Pran Buri, Hat Sai Noi); CENTRAL: Lop Buri (Sap Champa), Suphan Buri (U Thong, Bang Pla Ma), Samut Prakan (Pak Nam), Bangkok (Phu Khao Thong, Chatuchak); SOUTH-EASTERN: Chon Buri (Sattahip, Si Racha), Rayong (Klaeng); PENINSULAR: Chumphon, Ranong (Kraburi), Phuket (Hat Nai Yang), Nakhon Si Thammarat, Satun (Tarutao), Songkhla (Hat Yai).

Habitat and ecology.

In wastelands, open areas by the roadside, the edge of rice fields and the edge of deciduous and evergreen forests at elevations between 0 and 500 m above mean sea level (a.m.s.l.). Flowering and fruiting throughout the year.

Vernacular name.

Ya bung (หญ้าบุ้ง); Brown’s burgrass, Brown’s sandbur, Fine-bristle burgrass, Fine-bristle sandbur, Slim-bristle sandbur (English).

Specimens examined.

Thailand. Amnat Charoen: 28 Oct 2001, S. Laegaard & M. Norsaengsri 21856 (AAU, BKF, QBG) ; Bangkok: Bang Khen , 12 Nov 1952, K. Suvatabandhu 33 (BK); Chatuchak, Lat Yao, 26 Dec 2016, P. Wessapak 346 (BK); Kasetsart University, 12 Sep 2017, P. Wessapak 393 (BK); Phu Khao Thong, 18 Dec 1955, T. Smitinand 3147 (BKF); 14 Mar 1920, A. F. G. Kerr 4063 (BM, K); 5 Jan 1958, Th. Sørensen, K. Larsen & B. Hansen 22 (C, K); 4 Apr 1958, Th. Sørensen, K. Larsen & B. Hansen 7904 (BKF, C, K) ; Chiang Mai: Doi Suthep-Pui , 7 Nov 1988, W. Nanakorn et al. 2296 (QBG); Mae Rim, 8 Aug 1994, W. Nanakorn et al. 2167 (QBG); ibid., 15 Sep 1995, W. Nanakorn et al. 4219 (QBG); ibid., 28 Nov 1995, W. Nanakorn et al. 5377 (QBG); Mueang Chiang Mai, 13 Sep 1995, W. Nanakorn et al. 4277 (QBG) ; Chon Buri: Sattahip, 26 Nov 1964, S. Sutheesorn 224 (BK); Si Racha , 8 Nov 1992, J. F. Maxwell 92-709 (P); 30 May 1964, C. Hambananda 218 (BKF) ; Chumphon: 6 Apr 1967, S. Sutheesorn 2127 (BK) ; Kamphaeng Phet: Phran Kratai, Khui Ban Ong, Ban Rai Dong , 22 Oct 1992, J. F. Maxwell 92-648 (AAU, BKF, P) ; Kanchanaburi: Ban Kao , 8 Nov 1961, K. Larsen 8044 (C, K); Sai Yok, 15 Aug 2004, S. Sirimongkol 136 (BKF); Sai Yok, Lum Sum, 17 Feb 2000, J. F. Maxwell 00-61 (BKF); Sai Yok, Sai Yok Noi, 5 Nov 1979, T. Shimizu, H. Toyokuni, H. Koyama, T. Yahara & C. Niyomdham T- 21696 (BKF) ; Khon Kaen: Chum Phae, 29 Oct 2001, S. Laegaard & M. Norsaengsri 21870 (AAU, BKF, QBG); Khon Kaen University , 24 Oct 1982, P. Chantharanothai 247 (KKU); ibid., 20 Nov 1997, S. Saensuk s.n. (KKU) ; Lop Buri: Sap Champa , 19 Nov 1984, G. Murata, C. Phengklai, S. Mitsuta, T. Yahara, H. Nagamasu & N. Nantasan T-68121 (AAU, BKF) ; Nakhon Ratchasima: Pak Chong , 5 May 1971, P. Wisuthasom 10 (BK); ibid., 10 Oct 1979, T. Shimizu, H. Toyokuni, H. Koyama, T. Yahara & T. Santisuk T-18228 (BKF) ; Nakhon Sawan: 21 Jul 1973, G. Murata, N. Fukuoka & C. Phengklai T-16582 (BKF) ; Nakhon Si Thammarat: 27 May 1995, W. Nanakorn et al. 3626 (QBG) ; Phuket: Thalaeng, Hat Nai Yang , 12 Sep 1996, W. Nanakorn et al. 7455 (QBG) ; Prachuap Khiri Khun: Hat Sai Noi , 12 Nov 2017, P. Wessapak 435 (BK)]; Pran Buri, 11 Nov 2017, P. Wessapak 430 (BK); 14 Sep 1926, Put 241 (BK, BM, K); 18 Aug 1967, T. Shimitzu, N. Fukuoka & A. Nalampoon T-7644 (BKF) ; Ranong: Kraburi , 17 Jan 1987, J. Supapol 284 (PSU) ; Ratchaburi: Huai Yang , 9 Aug 1966, K. Larsen, T. Smitinand & E. Warncke 1326 (AAU, C, K, P) ; Rayong: Klaeng , 30 Apr 2017, P. Wessapak 365 (BK) ; Samut Prakan: Pak Nam , 22 Apr 1924, A. Marcan 1692 (BM) ; Satun: Tarutao , 23 Oct 1979, G. Congdon 99 (AAU, PSU) ; Songkhla: Hat Yai, Prince of Songkhla University , 11 Mar 1986, J. F. Maxwell 86-163 (AAU, PSU) ; Sukhothai: Sawan Khalok, D. E. Paray 17 (K) ; Suphan Buri: Bang Pla Ma, Phai Kong Din , 17 Sep 2017, P. Wessapak 399 (BK); U Thong, 26 Mar 2017, P. Wessapak 355 (BK) ; Tak: Ban Na, 20 May 1959, T. Smitinand 513 (BK); Rahaeng , 9 Jan 1904, E. Lindhard 56 (C, K) ; Uthai Thani: Khao Phraya Phai Ruea , 7 Sep 1975, S. Sutheesorn 3426 (BK) .

Note.

This species is similar to Cenchrus echinatus in terms of having involucre burr-like formation, but differing from the species by having a denser inflorescence, with the involucre usually having a longer outer bristle. In Thailand, it was introduced for foraging and has since become naturalised and is treated as a weed.

Figures

Figure 1. Cenchrus brownii Roem. & Schult A habit B ligule C spikelets with involucre D lower glumes E upper glumes F lower lemmas G lower paleas H upper lemmas I upper paleas J caryopsis. (Drawn from P. Wessapak 365 by Paweena Wessapak).

Figure 2. Cenchrus brownii Roem. & Schult A habitat B habit C inflorescence D spikelets with involucre. (Photographs: Paweena Wessapak).