Disakisperma eleusine (Nees) P. M. Peterson & N. Snow, Annals Bot. 109: 1327. 2012.

Snow, Neil, Peterson, Paul M. & Romaschenko, Konstantin, 2013, Systematics of Disakisperma (Poaceae, Chloridoideae, Chlorideae), PhytoKeys 26, pp. 21-70 : 45-47

Disakisperma eleusine (Nees) P. M. Peterson & N. Snow, Annals Bot. 109: 1327. 2012. Figure 3A-P

Diplachne eleusine Nees, Fl. Afr. Austr. 255. 1841. Uralepis eleusine (Nees) Steud., Syn. Pl. Glumac. 1: 248. 1854. Tridodia eleusine (Nees) T. Durand & Schinz, Consp. Fl. Afr. 5: 877. 1894. Leptochloa eleusine (Nees) T. A. Cope & N. Snow, Novon 8: 78. 1998.

Type.

SOUTH AFRICA, Katrivierspoort, JF Drège 3906 (lectotype: B!, designated by Snow (1998a); isolectotype: P!).

Description.

Perennials. Culms 50-130 cm tall, 2.5-4.0 mm wide at base, round, erect, rarely geniculate and rooting from lower nodes, arising from fibrous roots or sometimes from a knotted crown, branching or not; nodes glabrous; internodes 5-30 cm long, soft, hollow. Leaf sheaths longer or shorter than the internodes, round or slightly flattened, glabrous on the sides and margins; collar green or tan; ligules 0.8-1.4 mm long, membranous, often dark brown near base, apically truncate, erose or fimbriate; blades (3-) 15-30 cm long, 5-7 mm wide, cauline, linear, flat but becoming involute on edges, glabrous to minutely but densely scabrous above, nearly glabrous to moderately scabrous below, not disarticulating at base, midrib prominent. Panicles to 65 cm long, 1.5-3.0 cm wide, exserted at maturity; branches (1-) 3-9, (3-) 5.5-10.5 cm long, alternate along rachis, steeply ascending to erect, rigid, minutely scabrous, the axils glabrous or with a few short hairs. Spikelets 4.7-9.2 mm long, pedicels mostly less than 0.5 mm long, usually imbricate, 5-8 (-10)-flowered; callus glabrous; lower glumes 2.8-4.1 mm long, membranous, narrowly ovate, scabrous on midnerve, acute; upper glumes 2.9-5.3 mm long, membranous, ovate, scabrous on midnerve, acute; lemmas 3.2-4.2 mm long, 3- or sometimes 4-5 nerved (at least basally), membranous, ovate, smokey white, bronze, light green, lateral nerves distinctly raised, sericeous along lower half of lateral nerves, midnerves and often between nerves, the hair tips clavicorniculate, apex obtuse and sometimes bifid, awnless and often erose, hyaline; paleas subequal to lemma, elliptic to ovate, membranous, with short clavicorniculate or nonswollen hairs between lateral nerves, apex broadly acute. Anthers 0.9-1.0 mm long, brown or yellow. Lodicules 0.7-0.8 mm long. Caryopses 1.7-2.0 mm long.

Leaf anatomy. Ellis (1977) reported C4 NAD-ME anatomy for Diplachne eleusine , which we confirm here. Primary, secondary, and occasionally (e.g., Snow & Burgoyne 7021 [MO]) tertiary bundles are evident. Midrib present but lacking associated lacunae. Primary bundles easily distinguished from secondary bundles; tertiaries separable from secondaries based on much smaller diameter and absence of associated sclerenchyma girders. Primary and secondary bundles in fresh material projecting somewhat adaxially but not abaxially. Outer bundle sheath cells of primary and secondary bundles interrupted adaxially and abaxially. Extension cells occurring adaxially above primary and secondary bundles but more so over primaries. Sclerenchyma girders present adaxially and abaxially above primaries and secondaries (more so adaxially) but lacking from tertiaries. Colorless cells lacking between adjacent bundles; chlorenchyma continuous between all bundles. Bulliform cells between primary and secondary bundles but adaxial (above) to tertiary bundles [Vouchers: Snow & Burgoyne 6941 (MO), 7021 (MO); photographs of cross sections seen by the first author and housed at PRE: Ellis 2057, 2058, 2059, 2106, 3546, 3868].

Stem anatomy. Outer (subepidermal) ring of sclerenchyma present. Broadly triangular sclerenchyma girders (broadest near epidermis) arising from outer ring and projecting inwardly to connect with outermost ring of vascular bundles. Assimilatory tissue present, partially ringed by Kranz-like cells, in distinct patches between adjacent vascular bundles and associated triangular girders. Inner ring of sclerenchyma present, continuous, and several layers thick. Inner ring of vascular bundles scattered in the remaining cortical tissue but these mostly close to but not touching inner sclerenchyma ring. Cortical vascular bundles surrounded by sclerenchyma at least around their xylem-bearing portion [Voucher: Halse 29 (MO)].

Chromosome number. Not known.

Phenology.

Flowering year-round.

Distribution.

Native: Africa south of about latitude 20°S and most common in South Africa; growing in heavy clays to sandy soils, in rocky open sites or disturbed woodland or bushveld, infrequent to common. Elevation ca. 300 to 2000 m. (TDWG: BOT, MOZ, NAM, CPP-WC, CPP-EC, CPP-WC, TVL-GA, TVL-MP, TVL-NP, NAT-OO, SWZ). Non-native: None known.

Comments.

Disakisperma eleusine resembles the partially sympatric Disakisperma yemenicum . Both species have relatively few and erect panicle branches that bear moderately to tightly overlapping spikelets, florets with distinctly raised lateral nerves, lemmas and upper glumes occasionally with basal remnants of extra nerves, clavicorniculate hairs and similar caryopsis morphologies ( Phillips 1982; Snow 1996, 1998b). Disakisperma yemenicum is distinguished by having lemmas that are cartilaginous below with involute margins, leaf blades with scattered delicate, long hairs (3-5 mm long), smaller anthers 0.2-0.3 mm long, and shorter paleas (1/2-2/3 as long as the lemma). The base of the ligule is often dark brown in Disakisperma eleusine .

Conservation status.

Least Concern ( IUCN 2010).

Etymology.

The epithet eleusine probably was used to suggest that the species resembles Eleusine Gaertn.

Vernacular name.

South African sprangletop ( Snow 1997). Suggested name: Southern African Jacobsgrass.

Specimens examined.

Botswana. Central: Seleka Ranch, Hansen 3373(GABS). Mozambique. Lourenco Marques: Maputo, regiao de Changalane, próx. da Cabeca do Elefante, Myre & Carvalho 1847 (K). Maputo: Semi-riverine thicket, Hornby 2609 (K). Sul do Save: circ. Magude, entre Macaena e Panjano, Myre & Balsinhas 1572 (CANB, K); Prox. da povoacao da Moamba, Myre & Balsinhas 1628 (I); between Moamba & Boane, Schweichert 1896 (B, K, S, US); Entre Moamba & Ressano Garcia, Marques 2209 (K); Maputo, arredores de Catuanae, Myre & Carvalho 1434 (K). Namibia. Ausdauernde, aufrechte bis 1.30 m hohe Horste, Giess 8422, (M); ca. 25 mi E of Sesfontein, De Winter & Leistner 5884 (PRE). South Africa. Cape Districts, Sekoekoenieland, Stellenbosch, langs Olifansrivier, du Toit 124 (PRE); Dist. Kingwilliamstown, Kei Rd., Ranger 109 (PRE); Ft. Beaufort, Giffen 1630 (MO); Haha Haha Lagoon, Ellis 2106 (PRE); Fort Beaufort Distr., Killians’s grave, 5 mi NW of Fort Beaufort, Story 3875 (K); Dist. Queenstown, 38 mi SE by E of Queenstown, Acocks 17946 (K); Near Riv. Kei, Swallen 10575 (US); Albany [now merged with Cacadu], Lindsleath (sp.?) s.n. (US). East Cape District: Transkei, near the Kekau River, Drège 1840 (K). Kwazulu-Natal: Umzivulu, Schlechter 6424 (K); Ngotshe Distr., Farm Welcome, 42 km from Pongola on the road between Magudu & Candover, Koekemoer 125 (PRE); Louwsburg Distr., Itala Nature Reserve, Rangers house, Brown & Shapiro 166 (PRE); at False Bay, Godfrey & Bayer SH-1472 (PRE, US); Vryheid, Pole Evans 2641 (US); Slopes of Umkomaas Valley near Josephine Brodge, Otto 19993 (PRE); Ca 8.2 km S of Golela along hwy to Pongola, before “T” junction, Snow & Burgoyne 6954 (MO, PRE); Mkuze Game Reserve, A.J. Oates 1242 (US); Mkuze Game Reserve, Mahlobeni area, Snow et al. 6982 (MO, PRE); Ca 300 m from “T” intersection along dirt road leading to headquarters of Mkuzi Game Reserve, from dirt road leading S from town of Mkuzi, Snow & Burgoyne 6963 (MO, PRE); Zululand, Umfolozi Game Reserve, Guy & Ward 7 (PRE); Zululand, Prinshof Experimental Station, Pretoria, Phillips & Goossens 8785 (MEL, PRE, US); Zululand, Hluhluwe Game Reserve, Huntley 1735 (MO); Umtambanana, Halse 29 (MO, U); Nkansini, Tugela Valley, Smook 1817 (K, MO); N Weenen on Muden Rd, Acocks 13458 (BM, K); Inguavuma Dist., Ndumu Game Reserve, Pooley 1040 (K). Limpopo: Kruger N.P., Schÿff 3968 (K); Lebowa, Blouberg Mt., Farm Buffelshoek 261 on the SW side of the massif on the Blouberg geological series, Smook 7371 (PRE); Kruger N.P. 13 mi E of Skukuza, de Winter & Codd 529 (BM, K); Kruger N.P. 8 mi E of Skukuza, de Winter & Codd 524 (BM); Kruger N.P., 10 km east of Satara on Satara-Nwanedzi Rd. near Msasane Windmill, Ellis 3546 (PRE); Blaauwberg Tin Mine, Schweickerdt 2011 (B, BM, US); Lebowa: Stellenbosch, 56 km van Burgersfort op Pietersburg pad, draii NO af vir 10 km, du Toit 1001 (PRE); Noordelike kant van Soutpansberg, Nel 320 (PRE). Mpumalanga: Loskopdam Nature Reserve, along dirt road leading west from administration buildings, ca 2 km along road, Snow et al. 6941 (MO, PRE); Loskop Dam Nature Reserve, Ellis 2058 (PRE); Blyde Riv. Canyon Nature Reserve, north end of nature reserve, just off of Hwy R532, Snow et al. 7021 (MO, PRE); Bellevue, SO van Steilloopbrug, du Toit 161 (PRE); Distr. Potgietersrust, Springbuck Flats, de Winter 2331 (PRE). Swaziland. Farm Mlawula, below western edge Lubombo Mts, Upper Nkumbane Valley, small dam near Cyrildene fence, Culverwell 298 (PRE); 2-3 mi W of Border (with Natal) at Cecil Mack Pass, Maguire 8398 (M); Mlawula Nature Reserve, SARA campsite, Braun 119 (PRE).

Figures

Figure 3. Disakisperma eleusine (Nees) P. M. Peterson & N. Snow A habit B culm andinflorescence C sheath, ligule, and blade, ventral view D branch of inflorescence E spikelet F floret, ventral view G clavicorniculate hairs H lower glume I upper glume J lemma, dorsal view K palea, ventral view L palea, dorsal view M stamens and pistil N lodicules O caryopsis, dorsal view P caryopsis, ventral view. Drawn from Schweickert 1896 (US).