Flowers pale yellow, with red or reddish-purple blotches at throat; lower sepal saccate, 1.7-2.4 cm long, base abruptly constricted into an incurved, 1.5-2 cm long spur; dorsal petal semi-cucullate, broadly ovate or semi-orbicular, 1-1.3 cm long, 1.2-1.4