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Poaceae

Saccharum L.

Kingdom: Plantae Rank: Genus Parent: Poaceae Status: Valid

Common Names:

  • PLUME GRASS - English, United States of America
  • SUGARCANE - English, United States of America

Morphological Description

Diagnosis: Large, stout, reed-like perennials to several meters tall; leaves cauline, the blades elongate, flat; ligule a ciliate membrane 0.5–6 mm long; inflorescence a large, dense, terminal panicle, often conspicuously hairy; spikelets all alike, perfect, in pairs of 1 sessile and one pedicellate, 2-flowered, the upper floret fertile, the lower floret sterile; disarticulation below the pedicellate spikelet and in the inflorescence branch so that the sessile spikelet falls with associated pedicel and section of the inflorescence branch; callus (= base of spikelet derived from rachilla) usually with a tuft of long hairs, the hairs shorter than to longer than the spikelet; lemma of fertile floret of each spikelet with a long awn (awn absent in S. officinarum); palea of fertile floret ca. 1/2 as long as lemma; palea of sterile floret absent; stamens usually 2 (3 in S. officinarum).

Other

Notes: The genus, as treated here including Erianthus, comprises 35–40 species (Webster & Shaw 1995; Mabberley 1997; Webster 2003) of tropical and warm areas of the world. The center of diversity, with ca. 25 species, is tropical Asia (Webster & Shaw 1995). Like all members of the Andropogoneae, Saccharum is characterized by C₄ photosynthesis (Kellogg 2000a). The traditional segregation of awned species as Erianthus and awnless species as Saccharum has been described as “wholly artificial” (Clayton & Renvoize 1986). Some authorities (e.g., Daniels & Roach 1987; Whalen 1991) disagree, and they treat Saccharum more narrowly, including only SUGARCANE and its immediate relatives (only 5 species), with the rest of the species segregated into Erianthus. However, Burner and Webster (1994) successfully obtained hybrids between Erianthus species and SUGARCANE, and Burner et al. (1997) found North American Erianthus to be genetically similar to SUGARCANE cultivars. Nonetheless, recent molecular research (Dillon et al. 2001) raises the possibility that Saccharum officinarum (SUGARCANE) is derived from within Sorghum, while Erianthus appears more closely related to Zea; such results argue for the separate recognition of Erianthus. Likewise, Nair et al. (1999) found “considerable divergence” between Erianthus and Saccharum. Until such issues are resolved, we are following most recent authorities (e.g., Hatch 2002; Webster 2003) in treating Saccharum broadly, to include Erianthus. Saccharum is related to Eulalia, Imperata, and Miscanthus, and it also will hybridize with Sorghum (Gupta et al. 1978). Webster and Shaw (1995) indicated that the “single most reliable character for distinguishing among the [North American] taxa is the length of the callus hairs relative to spikelet length.” The long callus hairs may aid in dispersal by wind (Webster & Shaw 1995). The economically most important member of the genus is S. officinarum L. (SUGARCANE), which is the source of ca. 1/2 of the world’s sugar. Saccharum spontaneum L., WILD SUGARCANE, known in the U.S. from HI and PR, is a federal noxious weed (Kartesz 1999; USDA Natural Resources Conservation Service 2002). The following treatment draws heavily on Webster and Shaw (1995). (Latin: saccharum, sugar, referring to the sweet sap) (subfamily Panicoideae, tribe Andropogoneae)