Fresh flowers were harvested, and
divided into four stages according to floral development (Plate 1):
young bud stage, ends of sepals completely separated from each other
while ray florets being not opened yet (bud diameter 0.8–1.2 cm);
bud stage, ray florets being opened while tubular florets being not
opened yet (bud diameter 1.8–2.2 cm); young flower stage, ray florets
being opened while tubular florets being opened 20%–40% (face plate diameter
2.8–3.2 cm); flower stage, ray florets being opened while tubular
florets being opened 50–70% (face plate diameter 3.6–4.0 cm).