Most information on switchgrass plant structure and development is for plants from native prairies or cultivars released for forage. However, more botanical and anatomical information is forthcoming for bioenergy specific switchgrass strains. Switchgrass plants are strongly rhizomatous perennials that often form large clumps (Sutherland 1986). Tiller density is generally greatest in the spring and declines as the growing season progresses (Mitchell et al. 1998). The number of leaves per tiller varies by growth stage, genotype, and environment (Redfearn et al. 1997), with the maximum number of collared leaves present prior to advancing to the elongation stage for Trailblazer switchgrass ranging from 3 to 4 (Mitchell and Moser 1995). Ligules are 1.5 to 4 mm long consisting of a fringe of hairs from a membranous base (Sutherland 1986; Casler et al. 2012). Roots of established switchgrass plants have reached depths of 3 m (Weaver 1954).

Switchgrass reproduces sexually by seeds and asexually by rhizomes. The panicle inflorescence is diffuse and 15 to 55 cm long (Sutherland 1986; Casler et al. 2012). Spikelets are 3 to 5 mm long, are two-flowered with the upper floret perfect and the lower floret empty or staminate, and disarticulate below the glumes (Hitchcock 1951; Gould 1975; Casler et al. 2012). Florets are glabrous and awnless and the lemma of the fertile floret is slick and smooth (Casler et al. 2012). The seed is comprised of a smooth lemma and palea that hold tightly to the caryopsis (Casler et al. 2012). Glumes are unequal, with the first shorter than the second (Stubbendieck et al. 1997), and both are mostly removed by combining and cleaning (Casler et al. 2012). Switchgrass has been reported to contain 850 seeds g-1 (Wheeler and Hill 1957). However, Mitchell and Vogel (2012) demonstrated that differences in switchgrass seed weight exist within and among cultivars, reporting the seed number for 19 seed lots of four cultivars across two years ranged from 473 to 702 seeds g-1. Advantages to switchgrass seed are that it is easily threshed and cleaned (Casler et al. 2012) and commercial planting equipment can be calibrated easily to account for differences in seed lot seed number (Mitchell and Vogel 2012a). Unlike other native warm-season grasses, switchgrass seed is smooth and flows readily through grass drills. Additionally, a switchgrass seed industry has existed for over 50 years and numerous private companies and public crop improvement associations are involved in seed production, distribution, and marketing (Casler et al. 2012). The recommended seeding rate for switchgrass in the Great Plains is 300 to 400 PLS m-2 (Mitchell et al. 2010b), but successful stands can be established with seeding rates as low as 100 PLS m-2 if quality seed is used (Vogel 1987).