Poa subg. Parodiochloa (C. E. Hubb.) Soreng & L. J. Gillespie, 2025

Soreng, Robert J. & Gillespie, Lynn J., 2025, New species and infrageneric names in Poa L. (Poaceae): transferring species of Agrostopoa Davidse, Soreng & P. M. Peterson and Raimundochloa A. M. Molina and some notes on misidentifications, PhytoKeys 266, pp. 129-138 : 129-138

Poa subg. Parodiochloa (C. E. Hubb.) Soreng & L. J. Gillespie , comb. et stat. nov.

Parodiochloa C. E. Hubb., Brit. Mus. (Nat. Hist.), Bot. 8: 395. 1981. Type: Festuca flabellata Lam. ≡ Poa flabellata (Lam.) Raspail

≡ Poa sect. Parodiochloa (C. E. Hubb.) Soreng, Contr. U. S. Natl. Herb. 48: 579. 2003.

= Parodiochloa A. M. Molina (1986 a) , nom. illeg. hom. ≡ Raimundochloa A. M. Molina (1986 b) . Type: Koerleria trachyantha Phil (≡ Poa ana-molinae ).

Sections included.

Poa sect. Diversipoa , P. sect. Monandropoa Parodi (tentatively), P. sect. Parodiochloa , P. sect. Tzvelevia.

Poa chapmaniana and P. ana-molinae might be placed together in P. subg. Parodiochloa sect. Diversipoa . However, we wonder if the former might have arisen via hybridisation with other Poa species in North America like the annual P. bigelovii Vasey & Scribn. (originally included in Poa sect. Diversipoa ( Chrtek and Jirásek 1962) along with other North American annuals, all Hph types), which has similar lemma pubescence and infrequent reduction to 1 or 2 stamens where it approaches the geographic range of P. chapmaniana or even older hybridisations in Latin America ( Soreng 2007).

What is really going on will hopefully become apparent once more nuclear DNA of more species of Poa become available. We wonder if species with Rr genotypes were once more diverse and widespread, but continental American species nrDNA signals were mostly swamped out by concerted evolution and their chloroplasts displaced by in hybridisation with more numerous northern and southern Western Hemisphere species of Poa supersect . Homalopoa.

One stamen is rare in Poa , but P. tucumana Parodi , of the monotypic P. sect. Monandropoa ( Parodi 1962), also has one anther per floret. The species is known from the Argentinian Provinces Tucuman and Catamarca ( Giussani et al. 2012) and, here, it is tentatively placed in P. subg. Parodiochloa . A recent collection from the next province north (Prov. Salta; E slope of Sierra de Santa Victoria, 12 air km ESE of Abra Lizoite on new road to Santa Victoria, 4175 m elev., margins of a small alpine tarn, 22.26850 S, 65.11736 W, 29 Mar 2006, Peterson et al. 19606 US [voucher misplaced at US]), with its perennial habit, small stature and open panicles might belong to this species ( RJS recall). This accession aligns within the Parodiochloa clade in both plastid and nrDNA trees. Poa tucumana is small, slender perennial species exhibiting open panicles, small, 2 - flowered spikelets, glumes 3 - nerved, floret callus with soft, short (to 2 mm long) hairs, callus with woolly hairs surrounding the lemma base, lemmas 5 - nerved, unawned, keel scaberulous, lower body with a few minute appressed hairs, anthers one per flower, similar in some respects to P. chapmaniana ( Giussani et al. 2012) . Its slender unbranched stigmas, although vestigial, are reminiscent of the linear styles of P. flabellata .