This study examined floral heating and pollination in two Asian species of Illicium (I. dunnianum and I. tsangii). The researchers found that both species exhibited post-anthesis floral heating, with the highest temperatures occurring during the nursing phase to aid gall midge larvae. Pollination was exclusively by a new species of Clinodiplosis gall midge in both Illicium, unlike generalist-pollinated New World species. Ancestral state reconstruction showed that floral heating and gall midge pollination evolved independently in Schisandraceae. Post-anthesis heating provides a reward to the pollinating gall midges in their mutualistic relationship with the plants.

1. FLOWER HEATING
FOLLOWING ANTHESIS
&
THE EVOLUTION OF GALL MIDGE
POLLINATION IN SCHISANDRACEAE
AMERICAN JOURNAL OF BOTANY
JULY 2010

2. Shi Xiao Luo & Dianxiang Zhan
South China Botanical Garden,
Guangzhou, China
Shu-Miaw Chaw
Biodiversity Research Center
Taipei, Taiwan
Susanne Renner
Department of Biology,
University of Munich
Munich, Germany

3. KEY TERMS
• Agamospermy -the asexual formation of
embryos and seeds without the occurrence of
fertilization.
• Anthesis - the period during which a flower is
fully open and functional.
• Oviposition - to deposit or lay eggs.
• Saprophytic - organisms that feed on dead or
decaying matter.
• New World vs. Old World - NA vs. Asia

4. •Background Information
• Objectives
• Materials
• Methods
• Results
• Discussion

5. BACKGROUND INFORMATION

6. STAR VINE FAMILY
~90 SPECIES
Schisandraceae
Kadsura (22 species) - Endemic to Tropical Asia
Schisandra (25 species) - Tropical Asia- (Exception - S. glabra)
Illicium (42 species) - SE Asia, SE U.S., Mexico, Greater Antilles

7. WHY IS THIS PAPER INTERESTING?
• First Data Ever Published On
Thermogenesis & Pollination
In Any Asian Illicium Species
• TR-71U THERMO RECORDER

8. PREVIOUS STUDIES
POLLINATION BIOLOGY
(5 of 90 Species)
-Illicium floridanum
-Illicium parviflorum
-Schisandra glabra
-Schisandra henryii
-Kadsura longipedunculata
Thien et al., 1983;
White and Thien, 1985;
Deringer et al.,1999;
Liu et al., 2007;
Yuan et al., 2007, 2008

9. PREVIOUS EXPERIMENTS SUPPORT:
FLOWER HEATING:
1.) is a direct energy reward for ectothermic pollinators
2.) increases the volatilization of chemicals directed at pollinators
3.) helps the plant mimic mammalian feces or carrion attracting saprophytic pollinators
4.) enhances the respiratory release of CO₂, which in combination with other volatile
chemicals may stimulate fly oviposition

10. OBJECTIVES

11. OBJECTIVES
QUESTIONS AUTHORS ARE TRYING TO ANSWER
1.) Given that some Schisandraceae exhibit flower heating, do Asian
Illicium species also possess this trait?
2.) Does any flower heating continue after a flower’s sexual function
is over, and if so, what is the adaptive significance of postanthetic
flower heating?
3.) Are Asian Illicium species pollinated by gall midges, or do they
show “generalized” fly and/or beetle pollination similar to New World
Illicium?
4.) Are flower heating and midge pollination functionally correlated?

12. WHAT IS THE RELATIONSHIP?
ADAPTIVE SIGNIFICANCE?
POST ANTHESIS FLOWER HEATING
Schisandraceae Old World Illicium
GALL MIDGE POLLINATION

13. MATERIALS

14. STUDY SPECIES 1: Illicium dunnianum
DESCRIPTION: Small shrub (0.5 – 2m high)
HABITAT: Riverbanks in wooded ravines (Elevations 300-750m)
LOCATION: Shiheqiguan - Nan Kun Shan National Forest Park, China
OBSERVED: Mid March to late April – 2008 & 2009
# OBSERVED: 53 individuals total: (38 at site A, 8 at site B, 5 at site C)
STUDY SPECIES 2: Illicium tsangii
DESCRIPTION: Shrub or small tree (up to 10m)
HABITAT: Mixed forests or thickets (Elevations 500-800m)
LOCATION: Along road - Nan Kun Shan National Forest Park, China
OBSERVED: April to late May – 2008 & 2009
# OBSERVED: 56 individuals total

15. Illicium
dunnianum
Illicium
tsangii
Photo: Figure 1

16. METHODS

17. FLORAL DEVELOPMENT, FUNCTION, & TEMPERATURE
3 TEST GROUPS
Open Pollinated (Control)
Cross Pollinated
Bagged Pre-Anthesis
•
Relative position & color of tepals, stamens, and styles.
•
Presence or absence of secretion.
•
Timing of; style movements, anther dehiscence, and floral organ
wilting/abscission.
•
Recorded Ambient and floral temperatures in open-pollinated
flowers for 50 hours using TR-71U thermo recorder (AWESOME!)
Readings taken every 5 sec.

18. Plant Reproductive Biology
-Mating Systems-
1.) Randomly selected flowers and marked as controls
(open pollinated - natural)
2.) Flowers self pollinated from male-phase flower then bagged
3.) Flowers bagged to test for agamospermy
4.) Flowers cross pollinated then bagged

19. VISITORS & POLLINATORS
Diurnal & Nocturnal observations made over 150 hrs:
-Recorded Kinds & Numbers of Visitors
-Duration of Visits
-Insect Behavior
To investigate flowers functional phases
•
Visitor behavior was monitored inside flowers
•
Flowers were bagged at end of female phase
•
Flowers were bagged at end of male phase
•
Tepal tips were trimmed in male phase flowers
•
Tepal tips were trimmed at beginning of nursing phase

20. Molecular Phylogenetics
&
Ancestral Trait Reconstruction
•
Sequenced complete internal transcribed spacer (ITS) of ribosomal DNA
•
Sequenced part of the chloroplast trnL region
•
Data set comprised 43 species – 2197 aligned nucleotides
•
Performed Maximum Likelihood analysis under GTR + G model of
substitution
•
Bootstrap support values were estimated w/ 100 replicate heuristic searches

21. RESULTS

22. OBJECTIVES
1. Asian Illicium species do possess postanthe:c flower hea:ng.
2. The key stage of thermal warming was well aEer the sexual func:on was over in the two
studied species. The only observable & supported benefit of post‐anthe:c hea:ng is
exclusive to the larvae of the pollinator. The increase in temperature provides warm enough
temperatures for larvae to survive and the heat also causes filament and tepal secre:on
which the larvae feed on. The hea:ng seems to be a reward for the pollinator in a plant‐
pollinator mutualis:c rela:onship.
3. In contrast to the New World Illicium, the two study species Illicium dunnianum and I. tsangii
were pollinated only by Clinodiplosis gall midges.
4. Despite these findings, comparison of the ancestral state reconstruc:ons for two traits
showed that flower hea:ng and gall midge pollina:on are not strictly correlated.

23. Illicium
dunnianum
Illicium
tsangii
Photo: Figure 1

24. FLORAL TEMPERATURES (PHASE SPECIFIC)
Fig. 5. Above-ambient temperatures in Illicium dunnianum flowers during the day and at night. Mean above-ambient
temperatures in female-phase flowers, male-phase flowers, and nursing-phase flowers during the day were 0.4 ± 0.07 (mean ±
SE, N = 7735), 0.073 ± 0.001, and 2.52 ± 0.002 and at night 0.12 ± 0.001 (interim), 0.13 ± 0.001, and 2.49 ± 0.003. Mean
above-ambient temperature during the first 2 h of the female phase was 1.6 ± 0.1 (5A: 19:07–21:12 hours, N = 1441).

25. FLORAL TEMPERATURES... (PHASE SPECIFIC)
Fig. 5. Above-ambient temperatures in Illicium dunnianum flowers during the day and at night. Mean above-ambient
temperatures in female-phase flowers, male-phase flowers, and nursing-phase flowers during the day were 0.4 ± 0.07 (mean ±
SE, N = 7735), 0.073 ± 0.001, and 2.52 ± 0.002 and at night 0.12 ± 0.001 (interim), 0.13 ± 0.001, and 2.49 ± 0.003. Mean
above-ambient temperature during the first 2 h of the female phase was 1.6 ± 0.1 (5A: 19:07–21:12 hours, N = 1441).

26. Flower functional phases in Illicium dunnianum
♦ 1st night = Female flowers w/ fully receptive stigmas
♦ 1st day = interim phase (female to male)
♦ 2nd night = flowers entered male phase –last 2-3 nights (anther dehiscence)
♦ Day 3-7= Nursing phase begins
 Inner tepals close, forming a chamber,
 Adaxial filament surfaces and inner tepal bases produce a secretion,
 Filaments increased in diameter in control from female to nursing phase
 Filaments thickened from female to male and then wilted by nursing.

27. FEMALE PHASE
(Illicium dunnianum)
 Pollination occurred mostly at night
 Single midges entered same flower numerous times
 Only one midge at a time – if occupied other midges would fly away
 Midge eggs became visible & pollen grains appeared on stigmas after visits
 Single midges deposited 26 (+/- 3) pollen grains
 Captured midges carried numerous pollen grains on body
 New species of Clinodiplosis was likely discovered

28. MALE PHASE
(Illicium dunnianum)
 When anthers dehisced midges again visited to oviposit
 20 eggs were found per flower in the male phase, but flowers with trimmed tepals
caused eggs to die
 The highest number of larvae/ flower were found in the bagged male-phase.
 Highest number of eggs was found in male phase flowers
 High temperatures beginning of female phase then dropped to ambient during male
 Produced little heat during day and throughout male stages

29. NURSING PHASE
(Illicium dunnianum)
 At the onset of the nursing phase the chamber temperature increased to levels higher than in
female phase
 Gall Midges did not try to enter nursing phase flowers
 Larvae in nursing phase flowers were seen feeding on filament and tepal secre:on.

30. GALL MIDGE LARVAE
Fig. 7. Mean number of gall midge larvae in flowers of Illicium dunnianum.

31. Phylogenetic Distribution of Midge Pollination and
Flower Heating in Schisandraceae
Fig. 8. Maximum likelihood Schisandraceae adapted
phylogeny for Schisandraceae to gall midges several
based on combined nuclear times
and chloroplast data

32. DISCUSSION
‐Flower hea:ng evolved during the evolu:on of Schisandraceae and became co‐opted in flowers
pollinated by flower breeding midges?
‐Floral hea:ng helps odor emission??
‐Flower hea:ng aids in pollen tube growth??
‐Obligate outcrossing may be enforced by self incompatability??
‐Selec:ve factors behind the evolu:on of flower hea:ng??
‐Are midges simply co‐pollinators??

33. Works Cited
• Hao, G., M. L. Chye, AND R. M. K. Saunders. 2001. A phylogenetic analysis of the Schisandraceae based on morphology and
nuclear ribosomal ITS sequences. Botanical Journal of the Linnean Society 135: 401–411
• Liu, Z., G. Hao, Y. B. Luo, L. B. Thien, S. W. Rosso, A. M. Lu, AND Z. D. Chen. 2006. Phylogeny and androecial evolution in
Schisandraceae, inferred from sequences of nuclear ribosomal DNA ITS and chloroplast DNA trnL-F regions. International
Journal of Plant Sciences 167: 539–550
• Thien, L. B., D. A. White, AND L. Y. Yatsu. 1983. The reproductive biology of a relict: Illicium floridanum Ellis. American
Journal of Botany 70: 719–727
• Yuan, L. C., Y. B. Luo, L. B. Thien, J. H. Fan, H. L. Xu, J. Yukawa, AND Z. D. Chen. 2008. Pollination of Kadsura
longipedunculata (Schisandraceae), a monoecious basal angiosperm, by female, pollen-eating Megommata sp. (Cecidomyiidae:
Diptera) in China. Biological Journal of the Linnean Society 93: 523–536
• Yuan, L. C., Y. B. Luo, L. B. Thien, J. H. Fan, H. L. Xu, AND Z. D. Chen. 2007. Pollination of Schisandra henryi (Schisandraceae) by female,
pollen-eating Megommata species (Cecidomyiidae, Diptera) in south central China. Annals of Botany 99: 451–460.
• http://www.efloras.org/florataxon.aspx?flora_id=610&taxon_id=242326638