Propagation by Cuttings of the Federally Threatened Apios priceana (Fabaceae)

Apios priceana (Fabaceae) is a rare herbaceous perennial vine. Seed collection for ex situ conservation is difficult because seed production is sporadic. We investigated propagation by cuttings of A. priceana at Redstone Arsenal, Alabama. Two experimental factors were investigated: donor plant size (small vs. large) and month of cutting (May vs. June 2013). We also documented impact of cutting collection on donor plants by recording size and reproductive variables from both cut and uncut (control) plants. About one-third of cuttings formed tubers by May 2014; success did not differ due to donor plant size or month of cutting. However, May cuttings produced two-fold more tubers and had five-fold greater total tuber mass. Large donor plants grew more, and produced significantly more inflorescences and legumes than small donors. Cutting treatment alone did not significantly affect any donor plant variable, showing that donor plants recovered quickly after cuttings were taken. Significant interactions (for stem diameter and inflorescence production of donor plants) suggested that cutting more greatly stimulated regrowth of large plants cut in June. We conclude that propagation by cuttings can rapidly produce plants of this species for ex situ conservation, but there are trade-offs in outcomes. Cuttings taken in May have an advantage for tuber production (producing more tubers and greater tuber mass), whereas cuttings taken in June affect donor plants less (although this effect was modest). Overall, propagation by cuttings is a useful technique for this rare species as it produces new plants yet minimally impacts wild populations.