Grass Genera of the World

L. Watson and M. J. Dallwitz


Neeragrostis Bush

Sometimes referred to Eragrostis (‘E. reptans’)

Habit, vegetative morphology. Annual; stoloniferous, or decumbent. Culms 5–15 cm high; herbaceous. Leaves not basally aggregated; non-auriculate. Leaf blades linear (acuminate); narrow; 1.5–3 mm wide (1–3 cm long); flat; without abaxial multicellular glands; without cross venation; a fringe of hairs; 0.5–1 mm long.

Reproductive organization. Plants dioecious; without hermaphrodite florets. The spikelets all alike in sexuality (on the one plant); female-only, or male-only. Plants outbreeding.

Inflorescence. Inflorescence of spicate main branches (in the male), or paniculate (in the female); very contracted (in the female); capitate (in the female, ‘subcapitate’ in the male); digitate (in the male), or non-digitate (in the densely contracted female panicles); espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelets secund (male), or not secund (female); biseriate (male), or not two-ranked (female); subsessile to pedicellate.

Female-sterile spikelets. Male spikelets about 8 mm long, many-floreted, glumes unequal, lemmas 3 nerved; palea almost as long as lemma, 2-keeled; 2 fleshy lodicules, 3 stamens 1.5–2.5 mm long. Rachilla of male spikelets prolonged beyond the uppermost male floret. The male spikelets with glumes; without proximal incomplete florets; about 8–15 floreted. Male florets about 8–12; 3 staminate.

Female-fertile spikelets. Spikelets about 5–6 mm long; compressed laterally; disarticulating above the glumes; not disarticulating between the florets (the rachilla and paleas persistent). Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus absent. Callus absent.

Glumes two; very unequal; shorter than the spikelets; shorter than the adjacent lemmas; hairless; pointed; awnless; similar. Lower glume 1 nerved. Upper glume 1–2 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 about 8–12. Lemmas similar in texture to the glumes; not becoming indurated; entire; pointed (acuminate); awnless; often hairy (sparsely villous); carinate; 3 nerved. Palea present; conspicuous but relatively short (about half as long as the lemma); awnless, without apical setae; not indurated; 2-nerved; 2-keeled. Palea keels wingless; hairy. Lodicules present; 2; free; fleshy; glabrous. Stamens 0. Ovary glabrous. Styles basally fused (forming a persistent beak on the fruit). Stigmas 2 (conspicuously emergent at anthesis).

Fruit, embryo and seedling. Fruit small (0.8–0.9 mm long); ellipsoid; compressed laterally. Hilum short. Pericarp fused. Embryo large (0.3–0.4 mm long); waisted. Endosperm hard. Embryo with an epiblast.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; elongated; clearly two-celled; Enneapogon-type. Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhairs 90–250 microns long. Microhair basal cells 130–230 microns long. Microhair total length/width at septum 10–15. Microhair apical cells 15–25 microns long. Microhair apical cell/total length ratio about 0.1–0.2. Stomata common. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Intercostal silica bodies present and perfectly developed; tall-and-narrow, or cubical. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies present in alternate cell files of the costal zones; ‘panicoid-type’; not sharp-pointed.

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

C4; XyMS+. PCR sheaths of the primary vascular bundles interrupted; interrupted abaxially only. PCR sheath extensions absent. Leaf blade with distinct, prominent adaxial ribs to ‘nodular’ in section; with the ribs more or less constant in size. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; seemingly exclusively in simple fans. All the vascular bundles accompanied by sclerenchyma. Sclerenchyma all associated with vascular bundles. The lamina margins with fibres.

Taxonomy. Chloridoideae; main chloridoid assemblage.

Distribution, ecology, phytogeography. 1 species; southern U.S.A., Mexico to Surinam. Mesophytic; species of open habitats; glycophytic. River banks, sandy and open ground.

Holarctic and Neotropical. Boreal and Madrean. Caribbean.

References, etc. Morphological/taxonomic: Nicora 1962. Leaf anatomical: Nicora 1962.

Special comments. Very distinct from typical Eragrostis, judging from Nicora’s thorough description; but the distinction is blurred by (e.g.) E. hypnoides (Lam.) B.S.P. and especially by E. contrerasii Pohl, which is also dioecious with creeping habit.


Cite this publication as: Watson, L., and Dallwitz, M. J. (1992 onwards). ‘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.’ http://biodiversity.uno.edu/delta/. Version: 18th August 1999. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993 onwards, 1998), and Watson and Dallwitz (1994), and Watson, Dallwitz, and Johnston (1986) should also be cited (see References).

Index