Dual mechanisms of autonomous selfing in Roscoea nepalensis (Zingiberaceae)

The genus Roscoea, a Himalayan endemic and only alpine member of the predominately tropical family Zingiberaceae, is well-known for possessing elaborate floral traits commonly associated with biotic pollination, and particularly with long-tongued fly pollination. These traits include showy, easily detectable flowers with wide labellum serving as a landing platform for floral visitors, absence of discernible fragrance, presence of nectar as a reward, elongated reproductive organs situated away from the nectar source, and long corolla tube that is compatible with the tongue length of long-tongued insects (Goldblatt and Manning 2000, Cowley 2007). Consistent with these floral traits, most Roscoea spp. exhibit either obligate or partial biotic pollination (Zhang et al. 2010, Fan and Li 2012, Paudel et al. 2015,2017, 2019), while entirely autonomous self-pollination is rare (Zhang and Li 2008).