Diplachne fusca subsp. muelleri (Benth.) P.M. Peterson & N. Snow. Ann. Bot. 109: 1327. 2012.

Snow, Neil, Peterson, Paul M., Romaschenko, Konstantin & Simon, Bryan K., 2018, Monograph of Diplachne (Poaceae, Chloridoideae, Cynodonteae), PhytoKeys 93, pp. 1-102 : 27-31

Diplachne fusca subsp. muelleri (Benth.) P.M. Peterson & N. Snow. Ann. Bot. 109: 1327. 2012. Figures 3 , 4

Diplachne muelleri Benth., Fl. Austral. 7: 619. 1878. Leptochloa muelleri (Benth.) Stace, Watsonia 18: 413. 1991. Leptochloa fusca subsp. muelleri (Benth.) N. Snow, Novon 8: 78. 1998. Diplachne fusca (L.) Kunth var. muelleri (Benth.) J.M. Black, Fl. S. Austr. 1: 76. 1922. Diplachne fusca (L.) Kunth var. muelleri (Benth.) P.M. Peterson & N. Snow, Phytoneuron 2012-72: 2. 2012, isonym, nom. inval.

Type.

AUSTRALIA. Northern Territory: Charlotte Waters, Giles s.n., Herb. Wm. Munro (lectotype, designated here: K [K000899903, specimen on right side of sheet]!; isolectotypes: K!, US [734098]!).

Description.

Plants annual. Culms 15-100 cm tall, 1.5-3.8 mm wide at base, round, cespitose, erect or rarely geniculate below and rooting at lower nodes, usually branching (sometimes profusely); nodes glabrous; internodes 1.5-18 cm long, soft, hollow. Leaf sheaths longer or shorter than internodes, glabrous on sides and margins; ligules (1.5-)5-7.5 mm long; blades (3.5-)7-25 long × 0.2-0.5 cm wide, scabrous above, scabrous to nearly glabrous below. Panicles 5-35 × 2-7 cm, partially inserted below with 5-16 branches; the branches (0.7-)2-9(13) cm long, alternate or sometimes subopposite, ascending to erect, rigid, glabrous to minutely scabrous, axils glabrous. Spikelets 10-14 mm long, mostly imbricate; florets 8-13; callus glabrous; lower glumes (2.4-)3.3-4.7 mm long, narrowly ovate or somewhat irregularly asymmetric, glabrous, obtuse to acute apically; upper glumes 4-5.4 mm long, ovate, glabrous, obtuse and sometimes bifid; lemmas 4.7-5.8 mm long, 3-nerved, ovate, pale or smoky white, the lateral nerves pronounced and excurrent or not, sericeous to densely velutinous on lower 1/3-2/3 of lateral nerves, the midnerve usually somewhat less pubescent, apex acute, often bifid, mostly awnless or mucronate; paleas subequal to slightly exceeding lemma, obovate to narrowly ovate, sericeous to velutinous along lower 1/2 to 2/3 of nerves (hairs often diverging widely at maturity); apex obtuse to acute. Stamens 3; anthers 0.5-0.7(-1.0) mm long, yellow. Caryopses 1.6-2.4 × 1.0-1.1 mm long, obovate in hilar profile, depressed obovate in transverse section, hilar groove lacking, smooth, brown; pericarp weakly adnate to the endosperm.

Leaf anatomy.

Voucher: Badman 675 (CANB) (Fig. 5). Description as per D. fusca subsp. fascicularis .

Stem anatomy.

Not examined.

Choromsome number.

Unknown.

Phenology.

Flowering January through October.

Distribution.

Native: Widespread across inland Australia, particularly the central regions; wet areas such as streambanks, around boreholes, and swamps, in a variety of soil types (TDWG: WAU-WA, NSW, VIC, QLD-QU, NTE.) Elevation from near sea level, upper elevation unconfirmed. Non-native: TDWG: SWI; not confirmed.

Conservation status.

Least Concern ( IUCN 2012) due to its widespread distribution across Australia.

Etymology.

Named after German-Australian botanist Ferdinand von Mueller (1825-1896).

Vernancular names.

Mueller sprangletop; Mueller beetlegrass, Sugar Grass (in the Maranoa District of Queensland, Australia).

Comments.

Diplachne fusca subsp. muelleri is most easily recognised by the relatively narrow panicles, which are largely inserted at their bases and the presence of inflorescences at most points of branching on the culms. The mature lemmas often have a dark spot at the base at maturity, are relatively broad, flattened and the dense trichomes along the nerves typically spread widely at maturity.

Diplachne fusca subsp. muelleri most closely resembles D. f. subsp. fascicularis by virtue of the lower inflorescence branches that typically remain inserted at the bases, especially from lateral inflorescences. However, the upper glumes are generally much broader than the primarily North American subspecies.

Another occasional trait is a pronounced magenta to purplish mottling of the leaf sheaths (e.g. Carolin 6300 [US, K], Weber 8769 [US, W]), which typically is absent in D. fusca subsp. fusca , another native Australian subspecies, but which recurs sometimes in the American subspecies Diplachne fusca fascicularis . The relatively short spikelets of Lazarides 4381 (CANB), Chippendale 2036 (CANB), Hubbard & Winders 6263 (B, CANB), coupled with inserted, narrow panicles, suggest hybridisation between between D. fusca subsp. muelleri and Diplache fusca .

This subspecies is a relatively short-lived annual, whose relative abundance is often associated with the vagaries of water availability, particularly along watercourses and bores (=wells). The label of Symon 5617 (CANB, US) states the specimen grew relatively close to the hottest water emerging from the bore (ca. 110°F / 42°C). Cattle will graze the foliage and pastured horses eagerly consumed freshly collected specimens when offered (Snow pers. obs. 1996).

Specimens examined.

Australia. New South Wales: Tero Ck Station, Martensz G 308 (MU). Along road between White Cliffs-Tero Ck. Station, Martensz 4494 (CANB); Near Goonery Bore, 65 mi. E of Wanaaring, Moore 5785 (BRI,CANB); ca. 35 km NW of Milparinka, Hawker's Gate Rd. , Jacobs 3510 (BRI); 39 km from Brewarrina towards Collerina, Dunlop 933 (CANB); 11 km from Brewarrina towards Collerina, Dunlop 915 (CANB); "Mt. Mulyah", ca. 50 mi. NW of South, Moore 5010 (CANB); Calindary Station , Libke 4479 (CANB); Tero Ck. Stn., Martensz 2320 (CANB). Northern Territory: Burt Plain, 33 mi. N of Alice Springs, Must 487 (BRI, CANB); Ruby Gorge, Hale Riv., ca. 70 mi. ENE of Alice Springs, Beauglehole 20735 (BRI); Heavitree Range, Ormiston Gorge, Beauglehole 45280 (BRI); Twin Bore, Todd Riv. station , Latz 812 (BRI); 1 mi. S Long waterhole, Coniston Station , Latz 1192 (BRI, CANB); Busrt Ck., 36.5 mi. N of Alice Springs, Nelson 1653 (BRI, K); 24 mi. S of Barrow Ck., Perry 5352 (BRI, K); Heavitree Range, Ormiston Gorge, Beauglehole 45280 (BRI); North West Simpson Desert , Latz 4642 (CANB); Twin Bore, Todd Riv. Station , Latz 812 (BRI); Burt Plain, 33 km N of Alice Springs, Must 487 (BRI,CANB); Andado, Buckley 1280 (CANB); Palm Valley , Chippendale 2669 (BRI, CANB); ca. 8 km SW of Mt. Conner, Carr & Beauglehole 1959 (CANB); Coolata Springs, 30 mi. SSE of Mt. Ebenezer Station, Lazarides 6194 (BRI, CANB, K, US); Emily Gap, 10 mi. E of Alice Springs Township, Lazarides 5329 (BRI, CANB, MO, US); 1/ 2 mi. S of Yambah Station, Lazarides 5192 (CANB); Petermann Bore, Tempe Downs Station , Henry 558 (CANB); Livingstone Pass, Petermann Ranges, Carolin 6300 (US, K [n.v.]) 10 mi. SW Alice Springs, Swinbourne 792 (CANB); Mt. Denison Station , Martin 40 (CANB); ca. 13 km SSW of Alice Springs, Pullen 10525 (CANB); 24 km S of Barrow Ck. Township, Perry 5352 (CANB, US); 28 mi. NNE of Alice Springs, Perry 3340 (CANB, K); 5 mi. S Alice Springs, Paige s.n. (CANB); Bloodwood Bore (No. 25) 46 km SW Brunette, Must 516 (CANB); 5 km E Old Coniston Homestead, Latz 1170 (BRI, CANB); 8 km NNE of Willowra Homestead, Latz 1250 (CANB); 65.5 mi. NNW of Old Andado Homestead, Beauglehole 27805 (BRI); 9 mi. W of Old Andado Homestead, Beauglehole 27998 (BRI); 8 km SW of Mount Conner, Beauglehole 45738 (BRI); George Gill Range, Kings Canyon, along Kings Ck., Beauglehole 20294 (CANB); Alice Springs Airport entrance, Nelson 2067 (BRI); 28 mi. NNE of Alice Springs Township, Perry 3340 (BRI); Deep Well Rd. , 13 mi. S Alice Springs, Nelson 1832 (BRI); Palm Valley , Beauglehole 10351 (BRI); Palm Valley , Chippendale 2036 (CANB); Ruby Gorge, Hale Riv., ca. 70 mi. ENE of Alice Springs, Beauglehole 20735 (BRI); 1 mi. S of Long Waterhole, Coniston Station , Latz 1192 (BRI, CANB). Queensland: Burke Dist. , Sandhurst Bore, Millungera Station , Blake & Lazarides 4783 (K, MEL, NSW, US). Darling Downs Dist. , 16.5 km SE of Cunningham Hwy on Glenarbon Rd., NE of Texas , Snow & Simon 7311 (BRI, MO). Gregory North Dist. , W side of Lake Phillipi , Kamaran Downs Station , ca. 60 km W of Bedourie, Edmunds KN2 (BRI); 30-35 mi. S of Bedouire, Blake 12307 (BRI, K). Gregory South Dist. , Coochie bore, 55 km NW of Birdsville, Edmnuds AD62 (BRI); Earlstown between Quilpie and Windorah, Blake 5459 (BRI), Mulligan-Eyre Survey, Gasteen 11 (BRI); Between Betoota and Birdsville , Peart 1720 (BRI). Maranoa Dist. , Boatman Station ; "Bluebush Swamp", Everist 2857 (CANB, US). Mitchell Dist. , Near Lochnagar, Blake 10322 (BRI, CANB, K, NSW); Geera, E of Barcaldine , Blake 10371 (CANB, K); Walrus V, Site G 215, just S of Lake Mueller, ca. 29 km NE of Aramac on Lake Dunn Rd., McDonald 2672 (BRI). Warrego Dist. , ca. 14 km N of Thargomindah, Fairfax 1273 & Kemp (BRI); On Paroo Riv. channels, 7 km N of Hungerford, Eberson E202 (BRI). "Gilruth Plains", Allen 269 (CANB); “Curragh” Station, near Cunnamulla, Hubbard & Winders 6263 (B, CANB, NY); Eulo, White 11575 (K). South Australia: in the hot water from Murnpeowie flowing bore, Symon 5617 (B, CANB, K, US); Northern margin of Margaret Ck., ca. 30 km W of Coward Spring Railway Station, Weber 8769 (US, W); Between Camp and Rotten Swamp ca. 12 km NW of Quinyambie Homestead, Whibley 3587 (NY); Region 2, Lake Eyre Basin , Margeret Ck., near Curdimurka, Badman 492 (CANB); 16 km NE of Marree on the Birdsville Track, Badman 730 (AD, BISH); 1 km S of Anna Ck. HS, 16 km W of William Ck., Badman 1263 (BRI); Region 2, Lake Eyre Basin , N Lake Talinnie , O’Malley 374 (BRI); 34 km S of William Ck., Beauglehole 28112 (BRI); ca. 40 km W of Marree and 9 km in a southerly direction off the main road to William Ck ., Weber 9671 (BRI); Lake Eyre South , Sales and lower slopes of sandhills S of the lake, Badman 488 (CANB); Region 4: Gairdner-Torrens, Bates 16944 (CANB); Region 2: Lake Eyre Basin , Callanna Ck., 15 km W of Marree, Badman 378 (CANB); Region 2: Lake Eyre Basin , 4 km SE of Coward Springs, Badman 675 (CANB); Region 2: Lake Eyre Basin , km SE of Nunns Bore 28 km SE of William Ck., Badman 1876 (CANB); N of Marree , Lake Harry , McKean APG3 (CANB); Clayton Riv.... 50 km (ca. 30 mi) NE of Marree , Lothian L2011 (B); Near Queensland border, ca. 15 km NE of Innamincka, Whibley 2480 (B); Region 2: Lake Eyre Basin , Marree-Oodnadatta Rd. , 42 km by road NW of William Ck. , Donner 9870 (MEL); Lake Eyre Basin , 5 km E of Strzelecik Ck crossing, Williams 8023 (AD, BISH). Victoria: Near Mt. Everard , Giles s.n. (MEL). Western Australia: ca. 20 km E of Mulga Downs Headquartes, Mitchell PRP263 (BRI); Bore, 6.4 km W of Mongral Downs, Dunlop 2119 (BRI); 28 mi. E of Windidda, Eremean Prov. , Speck 1269 (CANB, US); Donkey Well, Yoothapina Station , Cranfield 5557 (CANB); Hadji Well, near Lake Way , Craven 5392 (CANB); Bore, 6.4 km W of Mongral Downs, Dunlop 219 (BRI); Bore, 6.4 km W of Mongral Downs, Dunlop 2119 (BRI); 28 mi. E of Windidda, Speck 1269 (CANB, US); Donkey Well, Yoothapina Station , Cranfiedl 5557 (CANB): Hadji Well, near Lake Way , Craven 5392 (CANB) . Switzerland. Derendingen, Probst 8902 (US, n.v.).

Figures

Figure 3. Inflorescence of Diplachne fusca subsp. muelleri (no voucher). Image by Mark Marathon (CC-BY-SA- 4.0).

Figure 4. Cross section of leaf of D. fusca subsp. muelleri (Badman 675) showing midrib (central area), midrib lacuna (ML) and vascular bundle with centripetal chloroplasts (CC) of the mestome sheath.