Functional traits of selected clones of southern sweet-grass (Hierochloë australis /Schrad./ Roem. & Schult.)
Southern sweet-grass (Hierochloë australis /Schrad./ Roem. & Schult., Poaceae), commonly known as a bison grass, is a perennial tuft grass rarely occurring in mixed forests in Eastern and Northern Europe. The raw material collected from this plant are leaves rich in coumarin compounds (especially coumarin) responsible for sweet, specific aroma of these organs. In Poland, southern sweet-grass leaves are used mainly for alcohol products aromatisation. Growing demand for the raw material results in uncontrolled and excessive collecting of this plant. The best way to solve this problem is to introduce this plant into cultivation. Since southern sweet-grass is allogamous and heterozigotic, strong intraspecific variability of the species is observed. Fourteen clones of selected individuals from one population of southern sweet-grass naturally occurring in East Poland were compared in respect of morphological traits as well as accumulation of biologically active compounds. The clones differed significantly in the weight of leaves (3.76–22.59 g of air-dry weight per plant). The total coumarin content (determined by a spectrophotometric method) in this raw material for investigated clones ranged from 1.49 to 1.94%, flavonoids – from 0.25 to 0.55%, and phenolic acids – from 0.20 to 0.42%. Three coumarin compounds were identified by HPLC, namely coumarin, 3,4-dihydrocoumarin, and o-coumaric acid. The content of coumarin ranged from 84.00 to 310.85, 3,4-dihydrocoumarin: from 17.80 to 168.45, and o-coumaric acid: from 37.50 to 70.00 mg · 100 g-1 dry matter.