Dichanthelium oligosanthes (Schult.) Gould var. scribnerianum (Nash) Freckm. & Lelong, scribner’s panicgrass, scribner’s rosettegrass. Perennial herb, rhizomatous (caudexlike), fibrous–rooted, many–stemmed at base, cespitose, principal shoot ascending with ascending lateral branch at successive nodes, in range to 45 cm tall; shoots with basal leaves and cauline leaves, leaves dimorphic, basal leaves without blades or with diminutive blades, cauline leaves photosynthetic and mostly > sheath; adventitious roots not formed aboveground.
Stems (culms) cylindric, to 2 mm diameter, tough, internodes to 40 mm long, with fine hairs to 2 mm long compressed by sheath; solid.
Leaves alternate distichous, simple with sheath; prophyll present in axil of each branch appressed to stem, long–acuminate, to 25 mm long, narrowly closed only at base, central panel without veins flanked by to 5 parallel veins on each half; sheath open and overlapping at node, to 35 mm long, back initially not ridged when dried conspicuously ridged, outer margin long–ciliate and inner margin ciliate on approaching collar, of basal leaves short–pilose and of cauline leaves base of sheath puberulent, without lobes (auricles) at top; ligule = a dense curtain of straight hairs ca. 1 mm long; collar ca. 1 mm long, whitish, ciliate on margins with enlarged bases; blade of basal leaves ovate, < 10 × 3 mm; blade of cauline leaves lanceolate, < 30—85 × 3.5—9 mm, flat, regularly minutely serrate–scabrous on margins (somewhat wavy), acute at tip, parallel–veined veins slightly raised on lower surface, glabrous but several hairs ± pustulate on margin close to collar.
Inflorescence spikelets, in terminal, open panicles, panicle ovoid, in range to 70 × 40 mm, spikelets < 10—28, nodes of lateral branchlets alternate, the branchlets spreading, to 30 mm long, having 1—3 branchlets and stalks of spikes per node, spikelet typically with 2 florets, lower floret sterile and reduced and upper floret bisexual, bracteate, lacking awns; peduncle of inflorescence to 240 mm long, of inflorescences on lateral branches much shorter and often with sheath of flag leaf concealing lower spikelets; axes lacking pulvinus, minutely scabrous, with tuft of puberulent hairs in fork, stalk of spikelet to 20 mm long, with spikelet terminal.
Spikelet obovoid, 3—3.2 × 1.8 mm, breaking below the glumes as 1 unit, never opening; glumes 2, unequal and dimorphic, lower glume deltate–ovate, ca. 0.85 mm long, encircling at base, widely acute at tip, upper glume obovate, ca. 2.5 mm long, green, encircling at base, acute at tip, 9–veined and ridged, not scabrous, in range glabrous; lemma of lower floret similar to upper glume, ca. 2.4 mm long, 7–veined and ridged, with short point at tip (umbonate), in range glabrous, lemma of upper floret acute–ovate, 2 mm long, fleshy (plump) and translucent, inconspicuously 2–veined, with margins incurved around palea (involute), glabrous and smooth, becoming hard (indurate) in fruit; palea of lower floret absent, of upper floret broadly ovate (never flattened), ± 1.8 mm long, translucent, 2–veined, with wide, margins inrolled around flower, short–truncate at tip, minutely dotted on back, glabrous, indurate in fruit.
Flower bisexual, cleistogamous; perianth (lodicules) 2, folded, ca. 0.25 mm long, whitish, lacking bulbous base; stamens 3, free, included; filaments 0.35 mm long, colorless; anthers dorsifixed, dithecal, 0.35 mm long, purplish red, longitudinally dehiscent; pollen colorless; pistil 1, 1 mm long, included and having stigmas mostly above level of anthers; ovary superior, obovoid, ca. 0.4 × 0.25 mm, opaque and whitish, glabrous, 1–chambered with 1 ovule; styles 2, not fused at base, colorless, stigmatic above midpoint having inconspicuously papillate (not plumose).
Fruit achene (caryopsis), firmly enclosed in hard (indurate) lemma and palea and spikelet dispersed as a unit, upper floret glossy, obovoid compressed on palea side, 2 × 1.5 mm, glossy tan or glossy and surfaces smooth; achene ellipsoid, ca. 1.7 × 1—1.1 mm, dull, smooth.
A. C. Gibson