Table 1.
Description of the flowering stages of individual flowers of Magnolia sprengeri.
Figure 1.
Morphology of an individual flower of Magnolia sprengeri at the pre-pistillate (A), pistillate (B), pre-staminate (C, D), staminate (E) and post-staminate (F) stages.
(A) Pre-pistillate stage: petals folded tightly with pistils opened. (B) Pistillate stage: functionally female flowers with receptive stigmas and immature stamens with no dehiscent anthers. (C) and (D) Pre-staminate stage: a floral chamber with appressed and unreceptive stigmas and non-dehiscent anthers. (E) Staminate stage: functionally male flowers with gynoecium starting to fade; stamens detached from the axis and the anthers dehisced. (F) Post-staminate stage: withered flowers with the petals and stamens becoming brown and abscised; the stigma withered. Abbreviations: An, androecium; Gy, gynoecium; Ip, inner petals; Op, outer petals; Tw, twig.
Figure 2.
Flower-visiting insects at different stages of anthesis.
(A) Aggregation of Bibio sp. on the surface of a swollen bud during the pre-pistillate stage. (B) Epuraea sp. foraging for pollen when the anthers were dehisced. (C) Polistes chinensis in a floral chamber at the staminate stage. (D) Brown lacewing (Hemerobiidae, Neuroptera) (left) and Epuraea sp. (right) crawling on the inner petals during the staminate stage. (E) Apis cerana foraging for pollen at the post-staminate stage.
Table 2.
Number of floral visitors to 46 Magnolia sprengeri flowers observed during the five floral stages.
Figure 3.
Visiting frequencies of sap beetles and bees on Magnolia sprengeri flowers at pistillate and staminate stages.
The observation was conducted on 6 flowers. Sap beetles and bees landing on the observed flowers for half an hour were recorded at an interval of 1.5
Figure 4.
Changes in temperatures and floral scents of Magnolia sprengeri during anthesis.
(A) Records of Magnolia sprengeri flower temperature (red line) and ambient air temperature (green line) during anthesis. (B) Difference between flowers and air temperature. (C) Relative proportions of dominant compounds (contributing to >5% of the blend) of M. sprengeri floral scents during the five flowering stages*. In (A), pictures a and b are infrared images of a M. sprengeri flower during the pistillate (a) and the staminate stages (b). Bar scales represent 1.5 cm in image a and 2 cm in image b. Colours indicate the temperature distribution. The red colour in the centre of the flower corresponds to the highest temperature. In (B), the same lowercase letters indicate no significant difference (p>0.05) in odour compounds between the floral stages according to the npMANOVA post hoc tests. Error bars indicate standard errors. Stage 1, pre-pistillate stage; Stage 2, pistillate stage; Stage 3, pre-staminate stage; Stage 4, staminate stage; Stage 5, post-staminate stage. * Relative proportions of chemical compounds accounting to >1% of the total floral scents differed significant (p<0.05) among all 7 samples.
Table 3.
Retention time and relative proportions (%) of chemical compounds identified in scents collected on 7 M. sprengeri flowers at different flowering stages (values in this table are means±s.e.).
Table 4.
Summary of the npMANOVA for the odour compounds of seven flowers sampled at the five floral stages. d.f. = degrees of freedom.