| # The grass genera of the world |

L. Watson, T.D. Macfarlane, and M.J. Dallwitz

### Pratochloa Hardion

~ Formerly referred to Eragrostis

Type species: P. walteri (Pilg.) Hardion.

Habit, vegetative morphology. Perennial; with culms tufted, semi-decumbent or floating. Culms when erect,to 114 cm high (or long, when decumbent or floating); herbaceous; self-supporting, or decumbent, or floating. Sheath margins free. Leaf blades linear (to 100 mm long); narrow; to 4.5 mm wide; without abaxial multicellular glands; not pseudopetiolate.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.

Inflorescence. Inflorescence paniculate; open to contracted (the sparse branches spreading or appressed to th main axis); espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund.

Female-fertile spikelets. Spikelets to 7 mm long (and 1.5–3 mm wide); compressed laterally; disarticulating above the glumes; disarticulating between the florets; with conventional internode spacings. Rachilla prolonged beyond the uppermost female-fertile floret. Hairy callus absent.

Glumes two; shorter than the spikelets; shorter than the adjacent lemmas; free; hairless; pointed (acuminate); awned to awnless (tapered into a thick, awnlike apex); carinate; very dissimilar to similar. Lower glume shorter than the lowest lemma to about equalling the lowest lemma; 1–3 nerved. Upper glume 1 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped; awnless. Spikelets without proximal incomplete florets.

Female-fertile florets 2–15. Lemmas not becoming indurated; entire; pointed; awnless (in coarsely tufted, erect specimens), or mucronate to awned (i.e., almost awned, in softer, diffuse forms of the plant). Awns if thus interpred, median; apical; non-geniculate. Lemmas hairless; carinate; 3–5 nerved; with the nerves non-confluent. Palea present; awnless, without apical setae; thinner than the lemma (membranous/hyaline); not indurated; 2-nerved; 2-keeled (the keels flat, broad over the lower two-thirds, narrowed to the apex and excurrent into a short soft mucro). Stamens 3. Anthers 0.6–1 mm long; not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Fruit free from both lemma and palea; ellipsoid. Hilum short.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; elongated; clearly two-celled; panicoid-type. Microhair apical cell wall thinner than that of the basal cell and often collapsed. Stomata common (5–6 rows per intercostal zone). Subsidiaries non-papillate; dome-shaped to triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Intercostal silica bodies present and perfectly developed. Costal silica bodies present and well developed; present throughout the costal zones; ‘panicoid-type’; cross shaped.

Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.

C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size to with the ribs very irregular in sizes (tending to alternate larger and smaller). Midrib not readily distinguishable; with one bundle only; without colourless mesophyll adaxially. The lamina symmetrical on either side of the midrib. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’. Sclerenchyma all associated with vascular bundles.

Classification. Watson & Dallwitz (1994): Chloridoideae (queried); main chloridoid assemblage (queried). Soreng et al. (2015): Arundinoideae; Molinieae. 1 species (P. walteri).

Distribution, phytogeography, ecology. South Africa.

Hydrophytic to helophytic, or mesophytic. In damp, sandy or brackish soils around seepage areas or stagnant pools, or in running water especially that of springs, often seeming calcicole.

References, etc. Morphological/taxonomic: Gibbs Russell et al. 1990, Van den Borre and Watson 1994, Hardion et al. 2017. Leaf anatomical: Ellis, 1984; Van den Borre and Watson 1994; studied by us, E. walteri Pilg. (= Pratochloa).

Special comments. Curiously, in terms of our compiled comparative data Pratochloa is closer to Eragrostis (from which it differs absolutely only in photosynthetic pathway-related characters), and even to assorted pooids and danthonioids, than to any of the arundinoids with which it is convincingly associated on molecular evidence (cf. Hardion et al (2017). Anatomical data more or less satisfactory.

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, and classifications. See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., Macfarlane, T.D., and Dallwitz, M.J. 1992 onwards. The grass genera of the world: descriptions, illustrations, identification, and information retrieval; including synonyms, morphology, anatomy, physiology, phytochemistry, cytology, classification, pathogens, world and local distribution, and references. Version: 15th June 2025. delta-intkey.com’.

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