Cenchrus clandestinus (Hochst. ex Chiov.) Morrone in Ann. Bot. (Oxford) 106: 127. 2010.

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

3. Cenchrus clandestinus (Hochst. ex Chiov.) Morrone in Ann. Bot. (Oxford) 106: 127. 2010.

Fig. 5

Pennisetum clandestinum Hochst. ex Chiov., Annuario Reale Ist. Bot. Roma 8: 41. 1903. Basionym.

≡ Kikuyuochloa clandestina (Hochst. ex Chiov.) H. Scholz in Feddes Repert. 117: 513. 2006.

= Pennisetum inclusum Pilg., Bot. Jahrb. Syst. 45: 209. 1910. Type: Uganda, Lamuru, 3,000 m alt., 30 Jun 1909, Scheffler 294 (holotype: B [B100168617]; isotypes: BM [BM000923356] seen on digital images, K [K000281293!], P [P00442923] seen on digital image).

Type.

Ethiopia, Semien , 27 Oct 1852, G. H. W. Schimper 2084 (lectotype, designated by Thulin and Phillips (2015, pg. 174): G [G00022569] seen on digital image; isolectotype: S [S-G-4663] seen on digital image) .

Description.

Perennial, mat-forming, stoloniferous. Culms prostrate, 5-15 cm high; nodes glabrous; internodes terete or semi-terete, channelled, 1-1.5 cm long, 1-2.5 mm in diam., glabrous. Leaf sheaths 1.1-1.3 cm long, usually distichous, margins hyaline with hairs, hairy or glabrous on both surfaces. Ligules a fringe of hairs, 1-2 mm long. Collar glabrous. Leaf blades linear, 1.7-7 cm × 2-3.5 mm, apex acute, based rounded or obtuse, chartaceous, usually folded, with or without pilose on both surfaces. Inflorescence very short spiciform panicle, ca. 2 × 0.2-0.3 cm (including bristles); central axis flattened, 4-5 mm long, scabrous; peduncle very short or sessile; 2-3 short racemes along central axis; raceme with solitary sessile spikelet subtended by an involucre of bristles. Involucre composed of numerous bristles, slender and filiform, 0.2-1.4 cm long, antrorsely scabrous; involucre falling with spikelet; stipe (raceme-based) absent. Spikelets dorsally compressed, lanceolate-linear, 1.6-1.8 cm × 1.2-1.8 mm, slightly curved. Lower and upper glumes absent. Florets 2. Lower floret sterile. Lower lemma lanceolate-linear, ca. 1.5 cm × 1.2-1.8 mm, apex acute, margins folded and membranous, chartaceous, glabrous, 9- or 11-nerved. Lower palea absent. Upper floret bisexual, persistent. Upper lemma lanceolate-linear, 1.6-1.7 cm × 1.2-1.5 mm, apex acute, margins folded and membranous, chartaceous, glabrous, 10- or 11-nerved. Upper palea lanceolate-linear, 1.4-1.6 cm × 1.2-1.5 mm, apex acute, membranous, glabrous, 4-nerved. Lodicules absent. Stamens 3; filament 3.5-5 mm long; anther yellow 2-3.5 mm long. Pistil ovary lanceolate, 1.8-2 × 0.3-0.4 mm; style 2; stigma plumose, 2-3 cm long, terminally distinct exserted. Caryopsis not seen.

Distribution.

Native to central-eastern tropical Africa and widely introduced and cultivated elsewhere.

Distribution in Thailand.

NORTHERN: Chiang Mai (Doi Inthanon, Mae Taeng).

Habitat and ecology.

This species is cultivated as a lawn grass. It grows well on upland and escapes to nearby areas at elevations of 1100-2650 m a.m.s.l. Flowering and fruiting from June to January.

Vernacular name.

Kikuyu grass (English).

Specimens examined.

Thailand. Chiang Mai: Doi Inthanon , 16 Oct 2001, S. Laegaard & M. Norsaengsri 21727 (AAU); Mae Taeng, Huai Thung Cho, 13 Jan 1986, Y. Paisooksantivathana y1760-86 (BK); Mae Taeng, Pa Pae, Thung Cho, 3 Jun 1981, Y. Paisooksantivathana & T. Chuaycharoern y616-81 (BK) .

Note.

This species is unique to the Cenchrus as it has a short spiciform inflorescence, partially exserted from the uppermost leaf sheath. Originally, this species was native to the tropical parts of Africa and has been widely introduced elsewhere for forage, urban landscaping, preventing soil erosion and is also considered as a weed in some countries ( Hosaka 1958; Cudney et al. 1993; Arango-Gaviria et al. 2019). In Thailand, there are a few specimens recorded in the natural habitat, maybe because its inflorescence is difficult to notice and its vegetative part is similar to other lawn grasses.

Figures

Figure 5. Cenchrus clandestinus (Hochst. ex Chiov.) Morrone A habit B ligule C inflorescence enclosed by terminal sheath D spikelet with involucre E stamens. (Drawn from S. Laegaard & M. Norsaengsri 21727 by Paweena Wessapak).