Sorghum is a relatively small genus of ca. 25-30 species. Most are confined to tropical and subtropical regions of the Old World (mainly Australia and Africa); a single species is native in the New World (Mexico; Mabberley 2008). None is native in Belgium.
Sorghum obviously is a heterogeneous assemblage. Numerous molecular phylogenetic studies have only partly resolved genetic relationships (Guo & al. 2006, Dillon & al. 2007).
Sorghum is an economically important genus. Several species are cultivated as cereal crops, especially in the warm-temperate and subtropical regions of the world. One of these, Sorghum bicolor, is the fourth most important cereal (Mabberley l.c.). Another species, Sorghum halepense, is both a widely grown fodder plant and a noxious agricultural weed.
As a result of intensive crossing the taxonomy of the cultivated species of Sorghum has become very complex, especially in the Sorghum bicolor complex. See further under that species.
- Annual grasses, rarely exceeding 100 cm. Leaves usually more than 25 mm wide. Bisexual (sessile) florets broadly ovate, up to 4(-6) mm wide, (rarely) awned or unawned, usually densely silky hairy, often not or tardily disarticulating. Male or sterile florets up to 6 mm long on pedicels of equal length. Panicle usually compact with short primary branches, usually broadly ovoid in outline === Sorghum bicolor
- Perennial grasses, often more than 150 cm tall. Leaves usually less than 20(-25) mm wide. Bisexual (sessile) florets narrowly ovate, up to 2 mm wide, awned or (rarely) unawned, not silky hairy, always disarticulating at maturity. Male or sterile florets much smaller on pedicels 1-1,5 mm long. Panicle more diffuse with longer primary branches, usually lanceolate in outline === S. halepense
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