Anthoxanthum, commonly known as vernal grasses or vernalgrasses, is a genus of flowering plants in the grass family Poaceae, placed in the order Poales. The genus comprises around 18–20 accepted species (with some authorities treating more when the closely related genus Hierochloe is subsumed), and GBIF records 53 descendants across all taxonomic levels.
Members of Anthoxanthum are slender, tufted annual or perennial grasses characterised by spikelets that turn yellow to golden at maturity — a trait reflected in the generic name. All species in the genus reportedly contain coumarin, a fragrant organic compound responsible for the sweet, hay-like scent of freshly cut or dried material, most famously in sweet vernal grass (Anthoxanthum odoratum).
The genus is widespread across temperate and subtropical regions of Africa and Eurasia, with several species occurring on tropical mountains. A number of species have become naturalised far beyond their native range, appearing in Australia, New Zealand, and throughout North and South America. Anthoxanthum odoratum is among the most familiar, growing commonly on acidic grassland and in bogs across northern Europe and introduced widely on other continents.
The relationship between Anthoxanthum and the genus Hierochloe (holy grasses) has long been debated: some recent authorities merge Hierochloe into Anthoxanthum, while others maintain them as separate genera pending further phylogenetic resolution.
Etymology
The name Anthoxanthum is Latinised Greek meaning "yellow blossom" (ἄνθος anthos "flower" + ξανθός xanthos "yellow"), referring to the golden colour of the mature spikelets. The common name "vernal grass" alludes to early-season flowering typical of many species.
Distribution
The genus is centred in temperate and subtropical Africa and Eurasia, with additional species on tropical African mountains. Anthoxanthum odoratum, the most widespread member, ranges from Iceland and the Canary Islands east to Mongolia. Several species have been introduced and naturalised in Australia, New Zealand, and North and South America.
Ecology
Anthoxanthum odoratum is a characteristic species of acidic grassland, heathland, and bogs in northern Europe, often indicating low-fertility soils. All species contain coumarin, which is released when plant tissue is bruised or dried and may deter some herbivores; coumarin is also used medicinally in many countries.
Taxonomy Notes
Some recent authors include the genus Hierochloe (holy grasses or sweetgrass) within Anthoxanthum based on molecular phylogenies, broadening the genus considerably. Others maintain the two as distinct pending further research. The former genus Hierochloe is the source of several species previously listed under Anthoxanthum.
