Tuesday, December 7, 2010

Early Morning anthesis

Flowers of Thysanotus chinensis (Liliaceae) open fully between around 7 am and 9 am. It was listed as rare in previous biodiversity survey.

Early morning anthesis is a common phenomenon scattered through angiosperms. Flowers of the early morning anthesis species open in early morning, probably soon after dawn and close before or around mid-day. It is suggested to prevent heat stress as anther and stigma would be destroyed by over-heating and closure of flowers would also reduce transpiration. These are reasonable explainations as most of the early morning anthesis species are herbaceous, grassland inhabitants.

It is important to note that early morning anthesis should be more related to the pollinator activity where it is the ultimate goal of floral anthesis. After a quick search on the literatures, bees were reported to be the major pollinators of early morning anthesis species including Pyrrhopappus carolinianus (Asteraceae) (Estes and Thorp, 1975) and Cassia fasciculata (Caesalpiniaceae) (Thorp and Estes, 1975). Bees were reported to forage actively for the pollen after dawn and their activities quickly reduced towards the mid-day. The close relationship between pollinator activity and timing of anthesis is interesting and I think the early morning thesis species in Hong Kong are also pollinated by bees as certain groups of them are particularly active in the morning. There is a number of candidates for observation including the ones shown here, namely Geissapis cristata (Fabaceae), Thysanotus chinensis (Liliaceae) and Xyris pauciflora (Xyridaceae).

Geissapis cristata (Fabaceae) is another rare species in Hong Kong which inhabits lowland wetland.

Xyris pauciflora (Xyridaceae) is commonly found near wet places in Hong Kong. All of the species listed here are having brightly-colored corolla. It is an important feature to send visual signal to pollinators and to offer them a landing place.

References:
Estes J.R. and Thorp R.W. (1975) Pollination Ecology of Pyrrhopappus carolinianus (Compositae). American Journal of Botany 62: 148-159.
Thorp R.W. and Estes J.R. (1975) Intrafloral behavior of bees on flowers of Cassia fasciculata. Journal of the Kansas Entomological Society 48: 175-184.

8 comments:

Roger Lee said...

Very interesting posts and have learnt a lot from them!! Thanks!!

Chun-Chiu, Pang said...

Hi Roger,

Thanks for visiting! Glad that you like the blog.

Best,
Chiu

Anonymous said...

Interesting post indeed. Would you mind telling me when was the photo of Geissapis cristata taken (which month)? Thanks. - Jackie

Chun-Chiu, Pang said...

Hi Jackie,

Thank you. The photo of the Geissapis cristata was taken in early October.

Cheers,
Chiu

Anonymous said...

Thanks. It should be Geissaspis instead (sorry for the wrong spelling in my article). It might have been introduced to southern China from the S and SE Asia. - Jackie

Chun-Chiu, Pang said...

Thanks. May I know where your information is from? I have just checked Flora of China and found that its distribution is quite strange - not continuous but discretely found in S Asia and two places in Guangdong (Guangzhou and Hong Kong). Thanks!

Chiu

Anonymous said...

Just a guess from its natural range and the sighting records in China. With its characteristic flowers and fruits this species is hard to be overlooked. Quite unusual that this is not found elsewhere in minaland China, or Taiwan, if this is a native species. - Jackie

Chun-Chiu, Pang said...

I see. This sounds reasonable! Thanks for your sharing!

Chiu