Hierochloe sect. Monoecia Connor (2012: 323)

Lema-Suárez, Irene, Sahuquillo, Elvira & Pimentel, Manuel, 2021, A revision of Hierochloe sect. Monoecia (Anthoxanthinae, Pooideae, Poaceae), Phytotaxa 478 (1), pp. 92-104 : 95

Hierochloe sect. Monoecia Connor (2012: 323) .

Type: Holcus redolens Vahl 1791: 102 ( Hierochloe redolens (Vahl) Roemer & Schultes 1817: 514 ).

Description: Perennial grasses; caespitose, densely clumped or lax, sometimes stoloniferous depending on the species. Stems erect or ascending, glabrous or hairy, cylindric with 2–16 nodes. Basal leaves in lateral shoots branching extra- and intra-vaginally, caulinar leaves with leaf-blades flat or convolute, upper surface smooth or deeply grooved; glabrous, pubescent, scabrous or scaberulous in both sides; upper leaves on the flowering stems with short blades. Ligule membranaceous, acute to truncate. Panicle condensed, spiciform to open, with well-defined spikelets. Spikelets pedicellated, laterally compressed, formed by 2 basal male florets, 1 apical female, protogynous floret and two glumes. Pedicels pubescent, scabrid or smooth. Glumes persistent, subequal, ovate-lanceolate, membranaceous or scarious, sometimes somewhat translucent, generally 1–3-nerved, shorter, equal or longer than the floret set. Basal male florets similar, paleate, tristaminate, obtuse to truncate, muticous or awned; awns apically, subapically or dorsally inserted. Apical female floret composed by two staminodes and a glabrous ovary with two plumose stigmas, exserted during anthesis. Lemma of apical female floret ovate, membranaceous and covering most of the palea, apex acute to obtuse, unkeeled or 1-keeled, with 3–5 nerves.

Leaf anatomy: Leaf epidermis with long cells type I3. Short cells present, mostly S5, rarely S2. Stomata in the adaxial surface or in both the adaxial and the abaxial surfaces. Leaves often ciliate and scabrid (hooks present). Bulliform cells present in some species. Median vascular bundle differentiated or not, with total or partial sheath. Subepidermal sclerenchyma continuous or discontinuous, more abundant in areas adjacent to the median nerve and the leaf margin ( Figure 1. A–E ).

Genome size and DNA-ploidy levels: Holoploid genome sizes (2C) range between 12.82 pg in H. pusilla and 27.43 pg in H. altissima . Assuming the basic chromosome number x = 7 for the group, H. sect. Monoecia includes 4 x, 6 x and 12 x taxa.

Habitat: Wet meadows, wetlands and grasslands on volcanic and sandy soils or in rock outcrops, 0–4600 m a.s.l. ( De Paula 1975, Connor & Renvoize 2009, Sede 2012).

Distribution: Disjunct distribution in South America: from Venezuela to Peru and from central Chile and Argentina to Tierra del Fuego and Falkland Islands ( De Paula 1975, Connor & Renvoize 2009, Sede 2012). There is an inverse relationship between elevation and latitude in H. sect. Monoecia: the species of H. sect. Monoecia in the northern and central Andes are restricted to tropical-alpine areas above 3500 m a.s.l., whereas in the southern Andes, they occur from near the coast to 2000 m a.s.l.

Figures

FIGURE 1. Hierochloe sect. Monoecia micromorphology details.A–C. Leaf transverse section. A. H. pusilla, leaf transverse section open with round ribs. B. H. juncifolia, leaf transverse section closed with polygonal ribs. C. H. redolens var. altissima, leaf transverse section open with quadrangular ribs. D–F. Leaf epidermis. D. H. redolens var. gunckelii, adaxial epidermis with long cells type I3 and stomata. E. H. pusilla, leaf epidermis with long cells type I3 and short cells S5 (round). F. H. juncifolia, leaf epidermis with long cells type I3 and short cells S2 (ax shaped).