Saturday, November 29, 2008

Asarum hongkongense

Genus Asarum L. (Aristolochiaceae)
contains about 90 species, mainly distributed in SE Asia. 39 species occur in China in which one is endemic to Hong Kong - Asarum hongkongense, a critically endangered species.

Flowers of Asarum are close to the ground and have strange shape. It is commonly believed that flowers of Asarum are pollinated by insects due to the traits of the flowers like the calyx surface ornamentation, tiny glands on the inner calyx surface and caudate sepal lobe extensions. Unlike most flowers of Aristolochia, flowers of Asarum give no bad odor which suggests Asarum is not imitating animal corpse that attract flies to pollinate. An old study suggested that the flowers resemble mushrooms that attract fungal gnats to lay eggs inside the flowers which may pollinate the flowers. However, more recent studies demonstrate that Asarum produces autogamous flowers which undergo self-pollination. The putative insect-attracting floral characters are therefore primitive which maybe derived from an insect-pollinating ancestor.

Flowers of Asarum are protogynous. The stigmas are receptive at the beginning of anthesis while anthers lie horizontally at the bottom of the flowers so that stigmas and anthers are spatially separated. In the later stages of the anthesis, the stamen filaments become erect (See the second picture) and the anthers dehisced to release pollen grains which promote intrafloral pollination. However, no detailed phenological study has been carried out for A. hongkongense so far, it is still not sure if its pollination mechanism is like such case.

Monday, November 24, 2008

Odorrana livida

Genus Odorrana is belonging to the family Ranidae which is comprised of 21 described species. Most of them occur in China where 16 can be found while the other 5 are in Japan. Odorrana livida is the most widespread species which is widely distributed in South-east Asia including India, China and Malaysia.

Recent study shows that Odorrana is most probably origniated at Mt. Hengduan and Plateau of western Yunnan where is the center of diversification of most fauna and flora. Odorrana is shown dispersing from the west to the east. Odorrana species occurring in the Southeast China, including O. livida, are more advanced within the genus.

Saturday, November 22, 2008

Sarcococca longipetiolata

Genus Sarcococca (Buxaceae)
A small genus comprises of about 20 species mainly distributed in Asia. 9 species can be found in China while 5 of them are endemic to China. S. longipetiolata is one of the endemic species which is narrowly distributed in Hong Kong, N. Guangdong and S. Hunan.

S. longipetiolata is a very rare species in Hong Kong that is restricted to Mount Parker on Hong Kong Island. It is therefore very susceptible to human disturbance or urban development.

It has no urgent need for conservation measure as it is located in the country park area where all wild plant species are protected by laws. However, visiting this rare species becomes a gimmick of some local eco-tours. Disclosure of the location of the species to the public might bring some unpreditable influence to it.

Sunday, November 16, 2008

Red-billed Starling (Sturnus sericeus)

Troops of Red-billed Starling flying around with loud noise are commonly seen in the winter in Hong Kong. They are believed to be winter visitors including passage migrants whose number reaches the peak during the first two weeks of November.

Pay attention if there is any other starlings mixing with the large flocks!

Wednesday, November 12, 2008

Impatiens hongkongensis

Genus Impatiens L. (Balsaminaceae)
The largest genus in Balsaminaceae which produces spectacular flowers. It comprises of over 900 species all over the world and ranges from India to South-east Asia. 240 has been found in China where most of them are distributed in the south-western part of China.

Impatiens hongkongensis is mostly found in wet places by streams and in ravines. It produces pale yellow flowers which may attract people to collect them from the wild for ornamental uses. It is thus protected under Forestry Regulations and listed in Rare and Precious Plants of Hong Kong.

Flowers of I. hongkongensis are probably protandrous (Presentation of pollens come befores stigma becoming active) to prevent self-pollination. Bombus species (Bumble-bees) and hawk moths are most likely to be the pollinators. However, detailed pollination ecology of the plant has not been studied. Too little is known so far for this narrowly distributed species.

Monday, November 10, 2008

Vespa discolor

Genus Vespa, also known as hornets, contains 22 species all over the world and eight (V. mandarinia is newly discovered) can be found in Hong Kong so far. They will construct their own colony comprises of a queen, males and workers. The nesting sites vary from one species to another and also intraspecifically.

Vespa discolor
is one of the most common hornets in Hong Kong. This species is un-aggresive and will not attempt to attack deliberately unless too much disturbance is caused to their nests. It is a generalist hunter and scavenger which prey on any kind of insects which they are able to kill (A wandering glider Pantala flavescens is killed in the picture). The nesting period of V. discolor is quite long which reaches 9 months from colony initiation to disintegration.

Eria sinica

Genus Eria Lindl. (Orchidaceae)
About 370 described species under the genus and they are mainly distributed in tropical Asia and Australia. 43 species are in China including 6 in Hong Kong.

Eria sinica is one of the smallest orchids found in Hong Kong while the whole individual shown in the picture is just about 1 cm height. It is apparently very similar to another native orchid Eria pusilla. These two species were mixed up before due to their great similarity in Hong Kong. They are sometimes found to grow together on steep sides of boulders together with mosses. It's very difficult to spot them even when they are flowering.

Eria sinica has a narrow distribution where it is only found in or near Hong Kong and Hainan province. The type specimen is also collected from Hong Kong. Eria sinica and all other wild orchids are protected under Forestry regulations in Hong Kong. I do think that everyone should not harvest and take the wild orchids. Everyone should has the rights to appreciate the orchids and other rare plants in the wild. Orchids blooming in the wild are always the most spectacular BUT not at the garden!

Sunday, November 9, 2008

Creobroter gemmata

It is recently reported that a mantid (identified as Creobroter gemmata) was seen jumping into a stream and a horsehair worm emerged through its anus in Hong Kong. Mantids are the common hosts of horsehair worm (Nematomorpha) in tropical and subtropical regions worldwide.

The horsehair worms copulate in its free-living stage and produce aquatic larvae. They are then actively ingested by other insects with aquatic larvae such as mosquitoe. They serve as vectors between the aquatic and terrestrial environment. The horsehair larvae continue their development if the insects are captured and eaten by mantids which are the final hosts of the worms. The worms then grow inside the mantids' abdomen and get maturity. They will then influence the hosts to approach water and emerge from the hosts. The factor influencing the hosts are still not understood.

Friday, November 7, 2008

Crested Mynah (Acridotheres cristatellus)

Crested Mynah is distributed through central and southern China and it is a common resident occurring throughout Hong Kong. It mainly inhabits agricultural areas, around fish ponds, villages and urban areas.

Local birdwatchers have seen that Crested Mynah attempted to kleptoparasitise Chinese Pond Heron deliberately. (This is a common breeding habit of cuckoos)

It is very social which are typically seen in flocks. The highest count of the aggregation recorded in Hong Kong was 600 at Chek Lap Kok on 7th Oct 07 according to "The Avifauna of Hong Kong".

Tuesday, November 4, 2008

Sonerila cantonensis

Genus Sonerila Roxb. (Melastomataceae)
Contains about 170 species distributed in tropical Asia. 12 are in the mainland where only one species are found in Hong Kong.

Though this species is described to be found in montane forest according to Flora of China, it is found at about 250 m a.s.l. in Hong Kong.