Monday, August 30, 2010

Fimbristylis thomsonii

Fimbristylis thomsonii (Cyperaceae) is a very common sedge in grassland or hillside in Hong Kong. There are several features making it recognizable in the field: conical spickelets where scales are spirally arranged; leaf-like bracts; many spickelets (usually more than 2); and 3 stigmas on a single style which could be visible when it is in stigma receptive phase. Habitat is also a very important clue to rule out those coastal species in the long species list.

It has quite a long flowering season which has been recorded to flower since April and I could still find many blooming ones at the end of August.

Friday, August 20, 2010

Firmiana simplex

Status of Firmiana simplex (Sterculiaceae) in Hong Kong is interesting. F. simplex is a very famous Chinese tree which is commonly cultivated in most parts of China where it is also originated from. However, most of the official literatures suggest wild populations of F. simplex in Hong Kong appear to be naturalized from cultivated individuals but not truly wild. Personally I am not convinced very much by this as many individuals are found far away from the hiking paths or main roads but in the valley. There is not many exotic woody species could invade into a new environment as successful as this. Also, wild populations of F. simplex are mainly concentrated to the Eastern part of Hong Kong but not the central and western regions. All these evidences seem not a natural consequence of naturalization of cultivated species but more likely to be true wild populations. Podocarpus macrophyllus shows a similar distribution in Hong Kong. Is this kind of biased distribution because of the oceanic micro-climate from the Eastern side of Hong Kong?

Firmiana simplex resembles Vernicia montana quite much if flower or fruit is not available. They are actually belonging to different family. The former is from Sterculiaceae while the latter is Euphorbiaceae. Glands are often present at the leaf base in Euphorbiaceae but lacked in Sterculiaceae. From the above picture, glands are absent at the leaf base which is a very useful clue to rule V. montana out. Also, F. simplex is sometimes called 青桐 (literally means tree with greenish bark). Picture below shows a very typical appearance of the bark of F. simplex.

Wednesday, August 18, 2010

Streblus taxoides

Streblus, a very unfamiliar genus to me, belongs to Moraceae where about five species could be found in Hainan but none in Hong Kong. I only managed to find immature fruits of S. taxoides during my visit to Hainan in late May. Moraceae usually produces syncarp like Ficus or Artocarpus but some of the genera also produces drupe like Streblus.

Monday, August 9, 2010

Syzygium impressum

Syzygium impressum (Myrtaceae) is a very recently described species which is only valid since 2008. Botanists from IBSC found some questionable specimens of Syzygium buxifolium which consistently differed from the typical one when they were preparing the Flora of Hong Kong. All of those specimens were collected from the Sunset Peak, Hong Kong. This taxon resembles S. buxifolium very much, but could be distinguished by its ovate leaves, impressed midveins and smaller fruits. It was later named as Syzygium impressum which was derived from its conspicuously impressed midveins.

There are nine Syzygium species in Hong Kong whereas identification based on vegetative parts is sometimes difficult. However, not many species have angled young branchlets where S. impressum is one of them (see below):

In addition, by careful assessment and observation, the midveins of it are conspicuously impressed adaxially.

The general apperance of it is indeed like small-leave Ilex species as its crown is very dense. Also, there isn't major habitat overlapping between it and S. buxifolium as the former is solely recorded from streamsides in montane forests but the latter is a very common shrub in lowland forest edge and shrubland.

The recent encounter reminds me that I had seen a very similar one apart from Sunset Peak. Unfortunately I didn't take any specimen or photographs at that time and there is no way to verify unless re-visiting the site. However, woody species is comparatively having lower chance to cause endemism especially in such a tiny place. It is not unexpected to find more populations of this currently-restricted species in other parts of Hong Kong, or even Guangdong. It might probably be overlooked in the past which was confused with S. buxifolium or its allied taxa.

Friday, August 6, 2010

Scincella modesta

Scincella modesta is one of the smallest skinks in Hong Kong. They move very quickly and love to hide themselves under leaf litter. They are particularly easy to see in mornings or evenings. The above photographs were taken at 17:30 in summer time.

Tuesday, August 3, 2010

Syzygium fluviatile

There is very few information and pictures of Syzygium fluviatile (Myrtaceae) available on internet and books after some intensive search. It might be because of its globally narrow distribution as it is probably a Chinese endemic. Even so, it is only found in three provinces in China, including Guangxi, Guizhou and Hainan according to Flora of China. However, a rapid biodiversity survey report prepared by KFBG, Hong Kong, stated that this species is endemic to Hainan. Indeed, it is a very common streamside shrub in Hainan based on my own observation. The specific epithet "fluviatile" means existing in or about rivers which is very true.