Pictured from left to right: Setaria glauca (2 photos), Setaria viridis (2 photos), and Setaria faberi
This genus is characterized by the bristly spike-like panicle. Nearly all spikelets are subtended by few to several, persistent bristles (considered to be reduced branches). As in Panicum, spikelets have 2 awnless florets, the lower sterile and the upper fertile with a hardened lemma and palea. The surface of the fertile lemma is transversely rugose. Our species are mostly stiff-stemmed plants, branching only near the base. Ligules consist of a fringe of hairs. In all species of Setaria, the bristles can cause eating disorders in livestock since they can become embedded in mouth tissues.
There are 5 species in MN; 5 are native.
Setaria glauca (see tair' ee ah glaw' ka)
- Synonyms: Setaria lutescens
- Common names: Yellow bristle grass, yellow foxtail
- Origin and habitat: Introduced from Eurasia; weedy in disturbed habitats
- Identifying characters: Mature bristles give the erect inflorescence a golden color. Leaf blades have long twisted hairs on the upper surface at the collar and sheaths are keeled. Mature fertile lemmas are strongly rugulose.
- Comments: The foxy-gold bristles on mature plants have provided this plant with some horticultural value in Europe. In this country yellow foxtail reseeds itself so readily, making it difficult to eradicate, that the beauty is overlooked. It is occasionally found in dried floral arrangements.
Setaria viridis (see tair' ee ah vir’ ih dis)
- Synonyms: None
- Common names: green bottlegrass, green bristle grass, green foxtail
- Origin and habitat: Introduced from Eurasia; cosmopolitan weed found in disturbed areas
- Identifying characters: Leaf blades generally have a whitish hardened margin, while the slightly compressed sheaths have ciliate outer margins (the inner margins are ciliate only near the collar). Inflorescences are slightly nodding at the tip, with yellowish-green to purple bristles. Mature feritle lemmas are rugulose.
- Comments: Similar to yellow foxtail (S. glauca), green foxtail has an inflorescence that is more curved, with purplish or greenish bristles that are broader than the capillary bristles found on S. glauca. The larger, similar colored Setaria faberi or giant foxtail, is a problem weed in cultivated areas. Growing up to 1.5 m tall, giant foxtail is characterized by droopy stems along with long (7.5-20 cm) droopy inflorescences. It also has longer spikelets (2.4-3 mm) than in S. viridis (1.9-2.5 mm).
Additional species in Minnesota:
Copyright 2002, A.F. Cholewa, J.F. Bell Museum of Natural History, University of Minnesota / No portion of this guide may be duplicated without written permission of author.