15. Eragrostis reptans (Michx.) Nees (creeping love grass, pony grass)
Pl. 149
c–e; Map 603
Neeragrostis reptans (Michx.) Nicora
Plants annual, dioecious, creeping widely by stoloniferous
main stems, low‑growing and forming mats. Flowering branches 3–15 cm
long, erect to ascending from sometimes spreading bases, glabrous or more
commonly short‑hairy, some of the hairs sometimes with glandular tips.
Leaves mostly overlapping, sometimes appearing fascicled, usually short‑hairy,
some of the hairs sometimes with glandular tips. Leaf sheaths with the ligule
0.3–0.6 mm long. Leaf blades 1–4 cm long, 1–3 mm wide, flat or less commonly
folded. Inflorescences dense, short panicles 1–3 cm long (the pistillate
inflorescences often appearing headlike), ovate to nearly circular in outline,
the inflorescences of staminate plants more open than those of pistillate
plants, both types with the axis and branches very short and glabrous or
minutely hairy. Spikelets 3–14 mm long, 1.8–4.0 mm wide, with 4–35 florets
(staminate spikelets with fewer florets than pistillate ones), very short‑stalked.
Pattern of disarticulation beginning with the glumes, the rachilla and florets
of staminate spikelets persistent, the lemmas of pistillate spikelets usually
shed with age, leaving the persistent paleas and rachilla. Lower glume 0.5–3.5
mm long (those of pistillate spikelets shorter than those of staminate
spikelets), narrowly elliptic‑lanceolate, usually short‑hairy.
Upper glume 1–4 mm long (those of pistillate spikelets slightly shorter than
those of staminate spikelets), elliptic‑lanceolate, usually short‑hairy.
Lemmas 2.1–4.0 mm long (those of pistillate spikelets slightly shorter than
those of staminate spikelets), lanceolate, sharply pointed at the tip, keeled,
the lateral nerves relatively conspicuous, glabrous or short‑hairy along
the nerves. Anthers 1.4–2.2 mm long. Fruits 0.4–0.6 mm long, ovate in outline,
not grooved, brown. 2n=60. August–October.
Uncommon in the northwestern quarter of the state, mostly in
the Missouri River floodplain (Illinois to Florida west to South Dakota and Texas; Mexico). Banks of lakes and rivers and edges of marshes.
This species is relatively uncommon throughout its range.
Some authors have segregated it into the genus Neeragrostis Bush, based
on its dioecious habit and several minor morphological and anatomical features.
Koch (1970) summarized the evidence that E. reptans merely represents a
morphologically specialized species within Eragrostis.