Scleria lithosperma [misidentified as Scleria biflora]

The above specimen is more likely Scleria lithosperma than S. biflora. After checking a bunch of literatures I found that nuts of S. biflora should be globose, regularly cancellate and beaked with black/purplish persistent style base. It is obviously wrong for the above specimen which is having obtusely trigonous, smooth and shining nuts. Both species could have simple inflorescence which is originally thought not the case for S. lithosperma.

I here keep the original message of S. biflora. However its status might not be correct:

Scleria biflora (Cyperaceae) is most likely the smallest Scleria species in Hong Kong. Inflorescence only bears one or two florets which gives its scientific name biflora. It is quite common in Hong Kong which can mainly be found in forest edge, shrubland or path side. However, the inflorescence or nuts are too inconspicuous which might usually be overlooked. It is also difficult to photograph where the above pictures are heavily cropped in order to show its inflorescence and nuts.

Fimbristylis cymosa

Fimbristylis cymosa (Cyperaceae) is one of the commonest Fimbristylis species seen in Hong Kong especially in the coastal or sandy shores. The height of the plant can be varied quite much which is ranged from about 10 to 40 cm. It has a compound inflorescence with relatively small spickelets. I roughly measured over 10 spickelets from several individuals and most of them are about 3 mm. One of the easiest way to distinguish this species from many other Fimbristylis is that it produces blackish nuts which gives its Chinese name "黑果飄拂草" (literally means black-nut Fimbristylis). Though some publications stated that its stigma is either bifid or trifid, so far I could only find the bifid one but none of them are trifid. I will correct myself if I did find the latter.

Rhynchospora corymbosa

Rhynchospora corymbosa (Cyperaceae) is a globally distributed species which is reported to be found in tropical and subtropical regions. However it was previously assessed as rare in Hong Kong which can only be found in a few localities. The above individual was found in an undescribed locality which is only holding a few individuals. It mainly inhabits lowland wetland or streamside which is, therefore, very vulnerable to disturbance, channelization, development and pollution. There is indeed quite a lot of wetland-associated species in Hong Kong so it's important to take care of this habitat in order to conserve this diversity.

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.

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.

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.

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.