Trigonochloa uniflora (Hochst. ex A. Rich.) P. M. Peterson & N. Snow. Ann. Bot. 109: 1328. 2012.

Snow, Neil & Peterson, Paul M., 2012, Systematics of Trigonochloa (Poaceae, Chloridoideae, Chlorideae), PhytoKeys 13, pp. 25-38 : 30-31

Trigonochloa uniflora (Hochst. ex A. Rich.) P. M. Peterson & N. Snow. Ann. Bot. 109: 1328. 2012. Figure 2A-H

Leptochloa uniflora Hochst. ex A. Rich., Tent. Fl. Abyss. 2: 409. 1851.

Craspedorhachis uniflora (Hochst. ex A. Rich) Chippind., Grasses and Pastures of South Africa 205, f. 182. 1955.

Cynodon gracilis Nees ex Steud., Syn. Pl. Glumac. 1: 213. 1854. TYPE: India, Ab. loco. Wight Herbarium 8895 (lectotype: K! designated here, no specimen number given in the protologue; isotype: K!).

Agrostis montana Krock., Fl. Siles. 1: 110. 1787. Agrostis montana Rottl. ex Hook. f., Fl. Brit. Ind. 7: 298. 1896, nom. inval. TYPE: India, Tinnevelly; at Palamcotta, 28 Nov 1895, Rottler s.n. (lectotype: K! designated here).

Craspedorhachis menyharthii Hack. ex Schinz, Bull. Herb. Boissier, ser. 2, 1: 770. 1901. TYPE: Mozambique, Boruma, Tanuar, L. Menyharth 665 (lectotype: Z!, designated by Phillips 1974: 277 [who did not include the collection number]; duplicate of lectotype: W!).

Leptochloa laurentii De Wild., Miss. Em. Laurent i. 207. 1906. TYPE: Democratic Republic of the Congo, Kiri, E. Laurent s.n. (holotype: BR! [seen digitally, June 2012; barcode BR0000008761873]).

Type:

Ethiopia, In valle fluvi Tacaze, Schimper 1707(holotype: P!; isotypes: B!, BM!, GH!, K!, MO!, PRE!, S!, W!, photo ex W!)

Description.

Plants annual (or possibly weakly perennial). Culms (15-)45-130 cm tall, 0.6-2.0(3.0) mm wide at base, generally erect, sometimes geniculate below and stoloniferous by rooting at the nodes, sometimes branching, arising from fibrous roots or occasionally from a short knotted-rhizome; internodes 2-8 cm long, soft, solid. Leaf sheaths mostly shorter than internodes, glabrous throughout or rarely sparsely pilose near the collar, the margins glabrous; collars green; ligules 1.5-3.5 mm long, broadly obtuse, lacerate; blades 1-13(-17) cm long, 5-14(-19) mm wide, ovate to broadly ovate, glabrous above and below, midrib prominent or not. Panicles 25-55 cm long, 5-8 cm wide with 22-90 branches, the branches 2.5-7.0 cm long, minutely scabrous, the axils mostly glabrous internally but short pilose on external side. Spikelets 1.9-2.7 mm long, 1-flowered or rarely 2-flowered, but if so, only a few per plant, nearly sessile or with minute pedicels less than 0.3 mm long, somewhat imbricate, callus area glabrous; lower glumes 1.8-2.3 mm long, narrowly triangular, minutely scabrous on midnerve, apex acuminate to mucronate; upper glumes 2.2-2.6 mm long, otherwise like lower glumes; lemmas 1.6-2.6 mm long, ovate, whitish or light green, the lateral nerves very faint, sparsely pubescent along nerves, apex awnless; paleas 1.5-2.5 mm long, subequal to lemma, narrowly ovate, glabrous, apex obtuse or sometimes acute; anthers ca. 1 mm long, dark purple to pale olive green. Caryopses ca. 1.2 mm long and 0.4 mm wide, trigonous in cross section, the surface smooth to slightly rugose-striate. 2 n = 36.

Phenology.

Flowering throughout the year when adequate moisture is available.

Distribtution.

This species isscattered through the eastern and southern portions of sub-Saharan Africa, rarely in India, most common in Sri Lanka in forests and shady areas on hillsides, well-drained and often sandy soils in disturbed and riparian areas; 0-1200 m. [TDWG: 22: GHA, NGR, ZAI (Dem. Rep. Congo); 25: KEN, TAN; 26: ANG, MLW, MOZ, ZIM; 27: BOT, NAM, NAT, TVL; 40: IND, SRL].

Conservation status.

Since the species is widespread it is of least concern ( IUCN 2010) given its widespread occurrence. However, the typical size of populations is undocumented. The thinly membranous leaves likely are sought after by grazers, although the relative nutrition content of the leaves is unstudied.

Etymology.

The specific epithet is from the Latin uniflora, with reference to the single floret per spikelet.

Vernacular names.

Common triangle-seed grass. Kenya: Mkuse - Digo (Magogo and Glover 477, W).

Comments.

The species description and distribution differ from Snow (1997) because some specimens therein were incorrectly identified as Leptochloa neesii .

Trigonochloa uniflora individuals vary significantly in growth habit. Most specimens are relatively delicate, sprawling annuals, but some specimens have more erect, relatively stout culms that appear to be weakly perennial. The more erect forms typically occur in somewhat more open areas and have thicker leaves, whereas the more slender forms that frequently root at the lower nodes, typically occur in shade and have thinner leaves.

The glumes of Trigonochloa uniflora typically are longer than the single floret and may be mucronate. The caryopsis is sometimes dispersed with a tightly adnate lemma and palea, which may enhance water absorption prior to germination. The apex of the leaf sheath can sometimes be sparsely pilose, whereas in contrast nearly all specimens of Trigonochloa rupestris have ciliate sheath margins. Many specimens of Trigonochloa uniflora from Sri Lanka resemble Trigonochloa rupestris based on thin, sprawling culms. Two culms on Exell et al. 1060 (BM) have a sparse covering of papillose hairs on the upper and lower surfaces of the leaf blades.

Two counts of 2 n = 40 ascribed to Trigonochloa (as Leptochloa ) uniflora by Gould and Soderstrom (1974) were misidentifications of Leptochloa neesii (vouchers at US!). We confirm the voucher with apolyploid count of 2 n = 36 based on x = 9 for Trigonochloa (Leptochloa) uniflora (Soderstrom and Kulatunge 1753, US!). In contrast, the count of n = 10 by Olorode (1975) has not been confirmed with a voucher.

Specimens examined.

Angola. Cuanza Norte: Cazengo, Welwitsch 2981 (BM, K); Cazengo, Gossweiler 4421 (BM, K); Granja de S. Luiz, Gossweiler 5200 (BM). Ab. loco, Gossweiler 2966(K) and 5444 (BM). Botswana. North-West: Riparian woodland, near Kasane,Blair Rains 67 (K, US).Dem. Repub. Congo.Haut-Katanga: Kibula, Callens 4776 (PRE). Kivu:Entre Nyangwe et Malela, Lebrun 5971 (PRE). Kongo Central: Kisantu, Vanderyst s.n. (US 889080). Tshuapa: Mpangu, Delhaye 440 (K). Province unknown: Gona, Vanderyst 5682 (US). Ghana. Ashanti: New Tafo, Lovi 3909 (K). Eastern:Aburi, Deighton 613 (BM). India. Kerala: “Palghat” [Palakkad], Madras Herbarium/South Indian Flora 16320 (US). Periakulam:Madurai, Matthew & Charles 51410 (K). Kenya. Coast: Longo Mwagandi Area, Shimba Hills, Magogo and Glover 477 (W); 50 mi SW of Mombasa, Shimba Hills, Bogdan AB3910 (P);Mombasa woodlands, Gibon s.n. (US 2954368); Kaya Muhaka, Luke 3405 (K); Forest between Umba and Mwena Rivers on Lungalunga-Msambweni Rd., Drummond & Hemsley 3787 (K, P). Malawi. Central:Dedza Distr., Mua-Livulezi Forest Reserve, Exell et al. 1060 (BM). Southern: Shire Valley, Hall-Martin 438 (MO); Lengwe Game Reserve, Hall-Martin 494 (K) and 582(K); Lengwe Game Reserve, NE corner, Brummitt 8884(K). Province Unknown: Mwenikumbila foothills, Jackson 1175 (MO). Mozambique. Manica:Maribane Forest, Chare 4434 (US); Amatongas Forest, near Gondola, Schweicherdt 272 (US). Sofala: Gorongosa N.P., Sangarassa Forest, 1 km W of Chitenga, Tinley 2497(K); Amatongas Forest, Schweicherdt 2341 (K, US). Zambezia: Malema, Torre & Paiva 11192 (PRE); Arredores de Mocuba, Torre 4908 (K). Namibia. Province unconfirmed. Mpilia Island, Killich & Leistner 3347 (K). Nigeria. Ondo: Idanre, Brenan & Jones 8731 (K). South Africa. Kwazulu-Natal:Mkuze Game Reserve, Ellis 3635 (PRE); Mkuze Game Reserve, parking lot by Bube (Kubube) Hide, Snow et al. 6978(MO, PRE); Tembe Elephant Park, Ward 1382 (PRE). Limpopo:Kruger N.P., Punda Milia area, Shipudza valley east of Punda Milia near Dongadziba, Ellis 3226 (K, PRE); Kruger N.P., ca. 12 km NW of Punda Milia, Davidse & Ellis 5925 (K, MO). Sri Lanka. Anuradhapura: Mihintale, Soderstrom & Kulatunge 1715 (CANB, K, TAES, US); Ritigala Strict Natural Reserve, ascent along eastern slope of Wannatikianda, Jayasuriya 1058(K, US). Central:54 miles N of Kandy toward Anuradhapura, trunk road A-9, marker 54/2, Gould 13250(US); Dambulla, Trimens 28(US); as previous, Ashton 998(K, US); Ruhuna N.P., Block I, Cooray 69030805R(US); Ruhuna N.P., Block I, Patanagala Camp, Clayton 5924 (CANB, K, TAES, US); Kumbukkan Oya, ca. 2 mi above mouth, at Megahakanda Meda Duwa Block 2, M-d Plot, R 16, Fosberg 51099 (US); Ruhuna N.P., Rugamtota on Menik Ganga (Plot 31), Fosberg & Mueller-Dombois 50192(US); Mennik Ganga (Riv.) 1 mile above Yalu Bungalow, Fosberg et al. 51045(US); Ruhuna N.P., Patanagala, Cooray 69120212R(K, US); Ruhuna N.P., Block 2, Cooray 69010502R(K, US); Ruhuna N.P., Block I, Rugamtota, Mueller-Dombois 69030704(US); Ruhuna N.P., Block I, next to Yala Camp site, Mueller-Dombois & Cooray 68013006(US); Ruhuna N.P., Block 1, in plot R13 between Andunoruwa and Komawa Wawa, Mueller-Dombois 69010713(US). Puttalam:Wilpattu N.P., Marai villu, Clayton 5597 (CANB, K, TAES, US). Trincomalee:Kantalai; road between Trincomalee and Kandy, Soderstrom & Kulantunge 1753 (CANB, K, TAES, US); Kantalai, 25 miles from Brincomalle on Kandy Rd., Ballard 1489(US). Tanzania. Iringa Region:Ab. loco, Greenway et al. 14075 (MO). Lindi Region:40 km W Lindi, Schlieben 5879 (B, BM, M, MO, S, US); Tendaguru, Migeod 104 (BM) and Migeod 126 (BM). Mahenge Region:Umgebung der Station Mahenge, Schlieben 1721 (BM, M, S). Morogoro Region:Uluguru-Gebirge, Schlieben 3630 (B, BM, G, M, S); 3 mi N Tunuguo, 30 mi SE Morogoro, Boaler 625 (B, US [2 sheets]). Province unknown.Rukwa Valley, Vuma Riv. near Zimba, Siame 581 (MO). Zambia. Central:Iolanda, N bank of R. Kafue, near Kafue town, Robinson 6440 (B, K, M); Kafue N.P., Musa-Kafue conflence, Mitchell 6/75(K). Eastern: Chikwa, ca 50 mi NW of Lundazi in Luangwa Valley, Robinson 822 (K, M). Northern: M’fume Camp, Verboom 922 (BM, K); Mporokoso,Lake Mweru-Wantipa,Richards 9117 (K, NY). Southern:Siburu forest, Sekute Chieftancy, Bainbridge 709 (BM); Victoria Falls, Crook 52602(K); Victoria Falls-Livingstone Island, Ellis 2780 (K, MO). Province unconfirmed. Kafue N.P., Mitchell 24/46 (B). Zimbabwe. Manicaland:Tanganda Tea Estate, Chipinga [now Chipinge], Brain 10615(K). Mashonaland West:Eastern Urungwe [=Hurungwe], tributary of upper Mauora, Phipps 868 (K). Urungwe,Chirundu, Simon 706 (BM). Masvingo: Bikita, 5 km E of Moodie Pass, Davidse et al. 6643 (BRI, K, MO, US). Matabeleleland North: Wankie [now Hwange], Kandahar Fishing Camp, Martin 87(K). Midlands: Gokwe, Sengua Research Station, Guy 2391(K).

Figures

Figure 2. Trigonochloa uniflora (Hochst. ex A. Rich.) P. M. Peterson & N. Snow A Habit B Inflorescence C Portion of inflorescence branch D Spikelet E Floret F Caryopsis, dorsal view G Caryopsis, ventral view H Caryopsis, cross section. A-C, F-G drawn from Ballard 1489; D, E drawn from Chare 4434.