Cenchrus echinatus L., Sp. Pl.: 1050. 1753.

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

4. Cenchrus echinatus L., Sp. Pl.: 1050. 1753.

Figs 6 , 7

= Cenchrus pungens Kunth, Nov. Gen. Sp. 1: 115. 1816. Type: Peru, Guyaquil, F. W. H. A. von Humboldt & A. J. A. Bonpland s.n. (holotype: P [P00669360] seen on digital image).

= Cenchrus brevisetus E. Fourn., Mexic. Pl. 2: 50. 1886. Type: Mexico, Orizaba, 1866, E. Bourgeau 3140 (lectotype, designated by Gutiérrez and Morrone 2012, pg. 266: G [G00099346], seen on digital image; isolectotypes: BR n.v., K [K000643125!]). ≡ Cenchrus echinatus L. var. brevisetus (E. Fourn.) Scribn., Publ. Field Columb. Mus., Bot. Ser. 2: 26. 1900.

= Cenchrus insularis Scribn. ex Millsp., Publ. Field Columb. Mus., Bot. Ser. 2: 26. 1896. Type: Mexico, Yucatan, Pagaros Island, 8 Mar 1899, C. F. Millspaugh 1759 (holotype: F n.v.; isotypes: B [B100278941] seen on digital image, US n.v.).

= Cenchrus hillebrandianus Hitchc., Mem. Bernice Pauahi Bishop Mus., Honolulu 8: 211. 1922. Type: Hawaii, Oahu, Waikiki, 19 Jun 1916, A. S. Hitchcock 13801 (holotype: US n.v.; isotypes: B [B100278942], BISH [BISH-439425] seen on digital images, K [K001056124!], P [P00698357] seen on digital image). ≡ Cenchrus echinatus L. var. hillebrandianus (Hitchc.) F. Br., Bull. Bernice P. Bishop Mus. 84: 65. 1931.

= Cenchrus echinatus L. var. glabratus F. Br., Bull. Bernice P. Bishop Mus. 84: 66. 1931. Type: Marquesas Islands, Nuku Hiva, F. Brown 745 (lectotype, designated by St. John 1976, pg. 419: BISH [BISH-92743] seen on digital image).

= Cenchrus echinatus L. var. pennisetoides F. Br., Bull. Bernice P. Bishop Mus. 84: 66. 1931. Type: Marquesas Islands, Nuku Hiva, Hakaui, 15 Jul 1921, F. B. H. Brown & E. D. W. Brown 657 (holotype: BISH [BISH-92748] seen on digital image).

Type.

Jamaica, 'Habitat in Jamaica, Curassa’, Anonymous s.n. (lectotype, designated by Veldkamp in Jarvis et al. (ed.) (1993, pg. 31): L [Herb. A. van Royen No. 912.356-116] n.v.; isolectotype: L [Herb. A. van Royen No. 912.356-103] n.v.) .

Description.

Annual, tufted, Culms geniculate ascending, 15-75 cm high; nodes glabrous; internode subterete, 5-15 cm long, 1-2 mm in diam., glabrous. Leaf sheaths keeled conspicuous, 5-9 cm long, margins hyaline, glabrous. Ligules a fringe of hairs, 0.8-1.2 mm long. Collar glabrous. Leaf blades linear, 14-32 cm × 4-8 mm, apex acute, base rounded, margins scabrous, chartaceous, glabrous on both surfaces, sometimes upper surface pilose. Inflorescence spiciform panicle, 16-35 × 0.9-1.6 cm (including bristles); central axis angular, 5-11 cm long; axis internode 2-3 mm long, scabrous to subglabrous; peduncle terete, 10-27 cm long, glabrous or scabrous; short racemes loose along central axis; raceme with 2-4(-6) spikelets in cluster, all sessile, subtended by involucre of burr-like spines and bristles. Involucre composed of outer and inner circles; outer circle usually shorter than inner circle; outer involucre of bristles, numerous and filamentous, free, 1-4(-5) mm long, retrorsely scabrous; inner involucre of 7-11 flattened spines, 4-7 mm long, connate at lower part as 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) 0.5-1.3 mm long, hairy, falling with raceme. Spikelets dorsally compressed, lanceolate, 4.5-6 × 1-2 mm. Lower glume ovate or lanceolate, 1-3 × 0.3-1.6 mm, apex acute or obtuse, membranous, glabrous, 1-nerved or nerveless, rarely absent. Upper glume lanceolate, 3.2-5.5 × 1.2-1.8 mm, apex acute or obtuse, membranous to chartaceous, glabrous, 3 or 5-nerved. Florets 2. Lower floret male or sterile. Lower lemma lanceolate, 3.8-5.8 × 1-2 mm, apex acute or acuminate, membranous to chartaceous, glabrous, 5-nerved. Lower palea lanceolate-oblong, 3.5-5.5 × 0.5-1 mm, apex acute to acuminate, margins folded with retrorsely scabrous, membranous, glabrous, 2-nerved, sometimes palea absent. Upper floret bisexual. Upper lemma lanceolate, 3.3-6 × 1-2 mm, apex acute or acuminate, margins hyaline, coriaceous, glabrous, 3 or 5-nerved. Upper palea lanceolate, 3-5.7 × 1-2 mm, apex acute or acuminate, margins hyaline, coriaceous, glabrous, 2-keeled, 2-nerved. Lodicules absent. Stamens 3; filament ca. 3 mm long; anther yellow, 1-2 mm long. Pistil ovary elliptic, 0.4-0.8 × 0.2-0.3 mm; style 2; stigma plumose. Caryopsis ellipsoid and gibbous or obovoid and slightly flattened, 1.5-3 × 1-2 mm.

Distribution.

Native to North America and South America. Introduced and naturalising elsewhere in tropical and temperate zones worldwide.

Distribution in Thailand.

NORTHERN: Tak (Thararak Waterfall); NORTH-EASTERN: Loei (Phu Ruea, Na Haeo), Udon Thani (Ban Dung), Khon Kaen (Mueang Khon Kaen, Phu Wiang, Khok Pho Chai); EASTERN: Nakhon Ratchasima; SOUTH-WESTERN: Kanchanaburi (Thong Pha Phum), Prachuap Khiri Khan (Pran Buri); CENTRAL: Saraburi (Muak Lek), Bangkok (Chatuchak); SOUTH-EASTERN: Chon Buri (Samaesan, Phanat Nikhom), Rayong (Klaeng); PENINSULAR: Songkhla (Mueang 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 600 m a.m.s.l. Flowering and fruiting throughout the year.

Vernacular name.

Ya khi khrok (หญ้าขี้ครอก), Ya son krachap (หญ้าสอนกระจับ); Hedgehog grass, Mossman river grass, Southern sandbur, Spiny sandbur (English).

Specimens examined.

Thailand. Bangkok: Chatuchak, Kasetsart University , 25 Dec 2016, P. Wessapak 347 (BK); ibid., 12 Sep 2017, P. Wessapak 394 (BK); 2 Mar 1987, J. Lambinon 87/10 (AAU) ]; Chon Buri: Phanat Nikhom, Kut Ngong, 29 Apr 2017, P. Wessapak 361 (BK); Samaesan , 8 Aug 1998, T. Wongprasert s.n. (BKF) ; Kanchanaburi: Thong Pha Phum, Pilog, Ban Pilog , 29 Jun 2004, S. Sirimongkol 123 (BKF) ; Khon Kaen: Khok Pho Chai , 24 Feb 2010, P. Thongson 14 (QBG); Mueang Khon Kaen, 25 Oct 2001, S. Laegaard & M. Norsaengsri 21791 (AAU, BKF, K, SING, QBG); Phu Wiang, 15 Sep 1994, W. Nanakorn et al. 1730 (QBG) ; Loei: Na Haeo, 20 Jun 1995, W. Nanakorn et al. 3829 (QBG); Phu Ruea , 24 Jul 2004, C. Jaroenchai 76 (KKU) ; Nakhon Ratchasima: 4 Sep 1989, Pasikarn & Prayad 41 (BK) ; Prachuap Khiri Khan: Pran Buri , 11 Nov 2017, P. Wessapak 431 (BK) ; Rayong: Klaeng , 30 Apr 2017, P. Wessapak 364 (BK) ; Saraburi: Muak Lek, Sap Sanun , 9 Jul 2017, P. Wessapak 372 (BK) ; Songkhla: Hat Yai , 23 Nov 2016, P. Wessapak, C. Ngernsaengsaruay, N. Meeprom & W. Boonthasak 337 (BK); Mueang Songkhla, 6 Oct 1990, B. Aksorn 6 (PSU); Sadao, 30 Jul 2013, H. Soh 24 (PSU) ; Tak: Mae Sot, Thararak Waterfall , 22 Jun 2005, R. Pooma, K. Phattarahirankanok, S. Sirimongkol & M. Poophat 5426 (BKF); ibid., 21 Aug 2010, M. Norsaengsri 7094 (QBG) ; Udon Thani: Ban Dung, Ban Dung Yai , 4 Dec 2008, M. Norsaengsri 4550 (QBG) .

Note.

The species is considered as a noxious weed in some countries ( Ensbey 2014; Verloove and Sánchez Gullón 2012). In Thailand, it was introduced for forage and has become naturalised and treated as a weed.

Figures

Figure 6. Cenchrus echinatus L. 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 361 by Paweena Wessapak).

Figure 7. Cenchrus echinatus L. A habitat B inflorescence C spikelets with involucre. (Photographs: Paweena Wessapak).