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Published In: Systema Naturae, Editio Decima 2: 1261. 1759. (Syst. Nat. (ed. 10)) Name publication detailView in BotanicusView in Biodiversity Heritage Library

Project Name Data (Last Modified On 7/9/2009)
Acceptance : Accepted
Project Data     (Last Modified On 7/9/2009)
Status: Native


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1. Tripsacum dactyloides (L.) L. (eastern gama grass)

Pl. 124 i, j; Map 509

Plants perennial, monoecious, with short, stout rhizomes, forming clumps. Flowering stems 70–250 cm long, erect or ascending, mostly unbranched, circular in cross‑section or slightly flattened, glabrous. Leaf sheaths rounded to keeled on the back, glabrous, the ligule a short membrane with a hairy (fringed) margin. Leaf blades 10–70 cm long, 7–20 mm wide, glabrous or somewhat hairy at the base, flat, the midvein noticeably thickened. Inflorescences consisting of 1–4 dense, spikelike racemes, these in a palmate (or nearly so) cluster at the tip of the stem, 10–30 cm long, with staminate spikelets toward the tip and pistillate spikelets in the basal 1/3–1/2, disarticulating at the axis joints, the staminate portion often shed as an intact unit. Staminate spikelets paired along 1 side of the flattened axis, both sessile or very short‑stalked, similar in size and appearance, the glumes 5–10 mm long, longer than the florets, elliptic, usually narrowed to 2 minute teeth at the tip, faintly 9–16‑nerved and usually 2‑keeled near the margins, firm, glabrous or minutely hairy at the tip. Staminate lemmas 4–9 mm long, elliptic‑ovate, thin, awnless. Anthers 3–7 mm long. Pistillate spikelets single, closely appressed to (appearing sunken into) concave portions on 1 side of the axis, with 2 florets, the lowermost usually sterile and reduced, the uppermost fertile. Glumes 5–9 mm long, the outer (lowermost) glume wrapped around and enclosing the rest of the spikelet, broadly ovate in outline, pointed or narrowed to 2 minute teeth at the tip, thick, hardened and bony at maturity, faintly many‑nerved, glabrous (the axis joints with small tufts of hair at the spikelet bases), shiny. Pistillate lemmas and paleas, 3–7 mm long, narrowly ovate, membranous, awnless. Fruits enclosed in the persistent glumes and axis joints. 2n=18, 36, 45, 54, 72, 90, 108; 2n=36 in Missouri. May–September.

Scattered throughout the state, most abundantly in the Unglaciated Plains Division (eastern U.S. west to Nebraska and Texas; south to South America). Upland prairies, glades, savannas, and less commonly openings and margins of mesic to dry upland forests; also roadsides, railroads, fallow fields, margins of crop fields, and disturbed, open areas.

Tripsacum dactyloides is a widespread, morphologically and cytologically variable species that has been split into a number of poorly defined varieties by some workers (de Wet et al., 1982). If such varieties are accepted, then the Missouri plants are all var. dactyloides. Missouri populations examined thus far are of the sexual, diploid type, (Anderson, 1944; Farquharson, 1955), but the widespread eastern and southern tetraploid race can produce seed apomictically and may eventually be found in the state. Gama grass is an important component of upland prairie vegetation and is considered highly desirable both as fodder for livestock and production of hay.



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