Flora of North America species comparison

Anthoxanthum odoratum is native to southern Europe. In the Flora region, it grows in meadows, pastures, grassy beaches, old hay fields, waste places, and openings in coniferous forests, occasionally in dense shade or as a weed in lawns. It is most abundant on the western and eastern sides of the continent, and is almost absent from the central region. In southern British Columbia, it is rapidly invading the moss-covered bedrock of coastal bluffs, and will soon exclude many native species. Diploids (In = 10) have been referred to A. odoratum subsp. alpinum (Á. Löve & D. Love) Hulten. Because the two ploidy levels can be distinguished only through cytological examination (Hedberg 1990), the two subspecies are not recognized here.

Anthoxanthum odoratum was often included in hay and pasture mixes to give fragrance to the hay, but this practice is waning. The aroma is released upon wilting or drying. By itself, the species is unpalatable because of the bitter-tasting coumarin.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Anthoxanthum is a cool-season genus of about 50 species that grow in temperate and arctic regions throughout the world. There are seven species in the Flora region, five of which are native. The fragrance emitted when fresh plants are crushed or burned is from coumarin. In addition to smelling pleasant, coumarin has anti-coagulant properties. It is the active ingredient in Coumadin, a prescription drug used to prevent blood clots in some patients after surgery. A disadvantage of coumarin is that it is metabolized by species of the fungal genus Aspergillus to dicoumarol, which induces vitamin K deficiency and a susceptibility to hemorrhaging in wounded animals. Because of this, using moldy hay containing Anthoxanthum as feed is dangerous.

This treatment follows the recommendation of Schouten and Veldkamp (1985) in merging what have traditionally be treated as two genera, Anthoxanthum and Hierochloe. In general, Hierochloe has less floral reduction, a less elaborate karyotype, and a higher basic chromosome number than Anthoxanthum (Weimarck 1971). The two genera appear distinct in North America but, when considered on a global level, Schouten and Veldkamp (1985) stated that the two genera overlap, with the placement of many species being arbitrary. Phalaris resembles Anthoxanthum sensu lato in its spikelet structure, differing only in the greater reduction of the lower florets. It also differs in lacking coumarin.

Anatomical studies (Pizzolato 1984) supported the close relationship of Anthoxanthum and Phalaris. Pizzolato also stated that although the bisexual florets of Hierochloe are described as terminal, a microscopic fourth floret is developed distal to the third (bisexual) floret.

Wherever they grow, the species that used to be treated as Hierochloe have been used by native peoples. Native Americans used them for incense, baskets, and decorations. In addition, they steeped them in water for a hair-, skin-, and eyewash, or for use as a cold medicine, analgesic, or insecticide. Early Europeans spread the species in churches at festivals. They can also be used to make ale (Stika 2003).

(Discussion copyrighted by Flora of North America; reprinted with permission.)