Observations of hawkmoth pollination in the South African orchid Disa cooperi

Johnson, S. D. 1995. Observations of hawkmoth pollination in the South African orchid Disa cooperi . - Nord. J. Bot. 15: 121–125. Copenhagen. ISSN 0107–055X.
Disa cooperi is a robust grassland orchid with long-spud white flowers which are strongly scented in the evening. Observations at a site in Natal province, South Africa showed that hawkmoths are frequent visitors to the orchid at dusk. The hawkmoth Basiothia schenki was an effective pollinator of D. cooperi; this hawk-moth has a medium length proboscis (x = 4.3 cm) which can be fully inserted into the nectar-containing spur of the orchid. Pollinaria are attached ventrally to the basal portion of the proboscis where it joins the head. Another hawkmoth, Agrius convolvuli , commonly foraged on nectar from D. cooperi , but did not carry pollinaria, probably because its proboscis is too long (x = 10 cm) to allow contact between the thick basal portion of the proboscis and the orchid column. Lips in Disa are typically linear and do not produce scent, thus the autapomorphic spathulate and scent-producing lip of D. cooperi indicates that hawkmoth pollination is derived in this species, probably from a long-proboscid fly pollinated ancestor.