Oloptum miliaceum (L.) Roeser & H.R. Hamasha, Pl. Syst. Evol. 298(365): 2012

Peterson, Paul M., Romaschenko, Konstantin, Soreng, Robert J. & Reyna, Jesus Valdes, 2019, A key to the North American genera of Stipeae (Poaceae, Pooideae) with descriptions and taxonomic names for species of Eriocoma, Neotrinia, Oloptum, and five new genera: Barkworthia, x Eriosella, Pseudoeriocoma, Ptilagrostiella, and Thorneochloa, PhytoKeys 126, pp. 89-125 : 99-100

Oloptum miliaceum (L.) Roeser & H.R. Hamasha, Pl. Syst. Evol. 298(365): 2012

Agrostis mileacea L., Sp. Pl. 1: 61. 1753 [Basionym] ≡ Achnatherum miliaceum (L.) P. Beauv., Ess. Agrostogr. 20, 146, 148. 1812 ≡ Urachne miliacea (L.) K. Koch, Linnaea 21(4): 439. 1848 ≡ Piptatherum miliaceum (L.) Coss., Notes Pl. Crit. 129. 1851 ≡ Oryzopsis miliacea (L.) Benth. & Hook. ex Asch. & Schweinf., Mém. Inst. Égypte 2: 169. 1887 ≡ Stipa miliacea (L.) Hoover, Leafl. W. Bot. 10(16): 340. 1966. Type: Sweden, Uppsala, Anon. s.n. (lectotype: LINN-HL84-2 [image!] designated by R.D. Meikle, Fl. Cyprus 2: 1794. 1985). Fig. 4A-E .

Distribution and habitat.

Oloptum miliaceum is native to Europe, particularly the whole Mediterranean region, from northern Africa, Sinai to Western Asia (Arabian Peninsula, Cyprus, Egypt, Iraq, Iran, Israel, Jordan, Lebanon, Palestinian territories, Syria, and Turkey) [ Freitag 1975; Soreng et al. 2003; Ibrahim et al. 2016]. It is naturalized in southern Africa, Australia, New Zealand, North America (Arizona, California, Maryland) and South America ( Barkworth 2007), and has been cultivated in Mississippi, North Carolina, Tennessee, and Utah (see SEINet http://swbiodiversity.org/seinet/collections/list.php?db=all&taxa=Achnatherum+miliaceum&usethes=1&taxontype=2&page=1). The species occurs in various disturbed habitats along roadsides, ditches, borders of fields, dry river beds, and dumping grounds usually below 2000 m ( Freitag 1975).

Comments.

The unique morphological features of this taxon (glabrous lemma with a central vein not grooved, 3-veined glumes without transverse veinlets, and a callus with a circular disarticulation scar) were first recognized by Roshevitz (1951) and later officially named by Freitag (1975) as Piptatherum sect. Miliacea Roshev. ex Freitag. Lemma epidermal pattern of Oloptum is unusual among achnatheroid grasses resembling only that of Celtica . It is distinguished by having long fundamental cells irregularly alternating with silica bodies. In our earlier molecular analysis, O. miliaceum is sister to the Eurasian Achnatherum clade in the core Achnatherum clade, which also includes Stipellula , Austrostipa S.W.L. Jacobs & J. Everett, Anemanthele Veldkamp and Celtica F.M. Vázquez & Barkworth ( Romaschenko et al. 2011, 2012).

Traditionally, two subspecies have been recognized. Oloptum miliaceum subsp. thomasii (Duby) Boiss. differs from the typical form in having densely verticillate panicles with 15-30 or more often sterile branches on the lowest whorl ( Freitag 1975). There is genetic variation between these two subspecies in our earlier analyses ( Romaschenko et al. 2011, 2012). A molecular study with a larger sample of the subspecies is necessary to fully explore evolutionary relationships.

Figures

Figure 4. Oloptum miliaceum: A panicle B glumes C floret D lemma and palea E lemma base with disarticulation scar. Ptilagrostiella kingii: F habit G panicle H glumes I floret J lemma apex.