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Flora
New records and clarification of some names of vascular plants in Hong Kong
by Ng Sai-chit, KFBG
Dendrophthoe pentandra (L.) Miq. in Fl. Ned. Ind. 1: 818, 1856.
Loranthus pentandrus L. in Mant. Pl. 1: 63. 1767.
On 29 March, 2001, Mrs Gloria Barretto presented to me some specimens from the family Loranthaceae that were collected from her garden 'Girashol' at Tai Po Kau. A closer examination of some of the flowering specimens (G. Barretto ex S.C. Ng 2927, 29 Mar 2001, New Territories, Tai Po Kau, (KFBG, HKU, AFCD)) revealed a taxon previously unrecorded in any of the local published checklists (Bentham 1860, Dunn & Tutcher 1912, Anon. 1978 & 1993; Xing et al. 2000). These specimens were keyed to Dendrophthoe pentandra (L.) Miq. using the keys by Kiu (1988) and Barlow (1997). The identity of these specimens was further confirmed by comparing them to a Kwangtung specimen of this species (G.W. Groff (HK24980), Apr 1918, Guangdong Province, exact locality unknown (AFCD)) identified by Xi Nianhe (IBSC, Guangzhou). No Hong Kong specimens of this species have previously been deposited in the AFCD Herbarium.
Without flowers, Dendrophthoe pentandra is similar to the locally abundant Taxillus chinensis (DC.) Danser in habit, but the former tends to have longer rhomboid elliptical leaves whereas those of the latter are usually more round. Among other locally occurring Loranthaceae, D. pentandra differs from Marcosolen cochinchinensis (Lour.) Tiegh. in having a single floral bract instead of three, and minutely hairy pedicels instead of glabrous ones. It also differs from Taxillus chinensis and Scurrula parasitica L. in having a 5-merous and radially symmetrical corolla tube. Similar to Helixanthera parasitica Lour., it has a racemose inflorescence, but it differs in having a short corolla tube instead of free petals.
Dendrophthoe pentandra is known to be distributed from E. India eastwards throughout Indochina to the Philippines (Barlow 1997). In China it has been recorded in Guangdong, Guangxi and Yunnan (Kiu 1988), and is locally common in Guangdong (Xing, F.W., pers. comm.). In Girashol it is a parasite of Scolopia saeva, Diospyros kaki, and Albizia julibrisson (introduced). Although it is not found in a truly wild habitat, it is apparently wild (G. Barretto, pers. comm.) and can live on native species. Hence, its presence in the nearby secondary forests of Tai Po Kau is to be expected.
Viscum diospyrosicolum Hayata in Icon. Pl. Formosan. 5: 192-193, f. 67-68, 1915.
On 27 May, 2000, while hiking with a team of youngsters at Tan Chuk Hang near Hok Tau, I was attracted by some fallen twigs of a leafless Viscum. A specimen of Viscum was then collected on the branches of a Cyclobalanopsis mysinifolia tree immediately above (S.C.Ng 2189, 27 May 2000, New Territories, Tan Chuk Hang, HKU). Closer examination of this specimen suggested that it was different from the other two known records of leafless Viscum species in Hong Kong (Viscum articulatum Burm.f. and V. liquidambaricolum Hayata). More flowering and fruiting specimens were collected from the same site afterwards (S.C. Ng 2225, 14 Jun 2000, same locality (HKU, AFCD); S.C. Ng 2841, 17 Nov 2000, same locality (HKU)). These specimens were keyed to Viscum diospyrosicolum Hayata using Kiu's key (1987). Their identify was confirmed by comparing to Kwangtung and Fujien specimens in the AFCD Herbarium that were identified as Viscum diospyrosicolum Hayata by Xi Nianhe (IBSC, Guangzhou) (Hodgins (HK25017), 15 Apr 1909, Fujien Province, exact locality unknown (AFCD); R. Mell (HK25018), 12 May, 1912, Pak Wan, Guangdong Province (AFCD); S.T.Dunn (HK25016), 11 Apr 1909, Swatow, Guangdong Province (AFCD); E.D. Merrill (HK25009), 26 Nov 1917, Guangzhou, Guangdong Province (AFCD)). No Hong Kong specimens of this species have been previously deposited in AFCD Herbarium.
This species has terete internodes (0.5-3 mm width) that are always widest at the top. In contrast, V. articulatum and V. liquidambaricolim have flat internodes (3-20 mm width) that are widest at the middle or upper-half of the internode. Compared to V. articularum, its fruit is orange instead of white.
It has been recorded throughout SW China to Taiwan, including Guangdong. Locally in Hong Kong, the population where my specimens were collected is so far the only known site for this species.
Smilax aberrans Gagnep. in Bull. Soc. Bot. France 81: 71, 1934.
Smilax ovalifolia auct. non Roxb.: Anon., Check List HK. Pl., 1993, name only.
On 5 February, 2001, I went to the forest at Sunset Peak (Lantau) to enjoy the cool and misty upland weather of Hong Kong's early spring. On my way ascending along the Wang Lung Hang Path, I walked into the ravine forest immediately before the patch of Asarum hongkongense. At around 600 m, I encountered five flowering and fruiting individuals of an unusual Smilax species with no spines and tendrils, and having dark purple flower petals (S.C.Ng 2888, 5 Feb 2001, Sunset Peak, Lantau (HKU, AFCD); S.C.Ng 2889, 5 Feb 2001, Sunset Peak, Lantau (HKU)). Two individuals of the same species were encountered again in the forest on the north side of Mt. Nicholson on Hong Kong Island at 350 m (S.C.Ng 2907, 20 Feb 2001, Mt. Nicholson, HK Is. (HKU, KFBG)). These specimens were keyed down to Smilax aberrans Gapnep. using the key in Chen & Koyama (2000). Although not mentioned in any of the published checklists, examination of specimens in the AFCD Herbarium revealed that similar specimens had been collected on Victoria Peak (Anon. (HK7589), 16 Jun 1913, Mt. Victoria, HK. Is. (AFCD)) but were misidentified as Smilax ovalifolia Roxb. (Anon. 1993). Interestingly, neither S. ovalifolia or S. aberrans were mentioned in Xing et al. (2000). Another specimen, collected on Sunset Peak (Y.W. Lam 1365, 9 Feb 1999, Sunset Peak, Lantau (AFCD)), had been misidentified as a Heterosmilax sp.
This species is a subshrub less than one metre tall and with no tendrils, whereas all the other local Smilacaceae species and Smilax ovalifolia are climbers with tendrils. Although occasional Smilax china have a similar growth form in open exposed shrubland, tendrils are always present. Leaves of S. aberrans have a similar shape and size to S. china but the undersides are usually minutely papillose and have a heavily whitish colour that could not be rubbed off, as it can in S. glabra and S. corbicularia. Both lateral and reticulate veins are obviously depressed on the upper sides but raised on the underside. Male flowers have dark purple petals instead of white or pale green as in other local Smilax species. Stamens are erect but short and usually less than one third of the length of petals. Fruit is black instead of red as in S. china.
This species is regionally widespread and has been recorded from Yunnan to Guangdong and Vietnam. During my last trip to NW Guangdong, this species was found to be locally common.
Carex fenghuangshanica S.F. Wang & T. Tang ex P.C. Li in Acta Phytotax. Sin. 37(2):168, fig. 7, 1999;
C. speciosa auct. non Kunth.: J.C. Shaw, HK. Cyperaceae Tax. Eco. & Geog. 2:29-30, 2000; C. speciosa var. angustifolia auct. non Boott.: Anon., Check List HK. Pl., 1993, name only.
In Volume 12 of Flora Reipublicae Popularis Sinicae (Dai et al. 2000), a recently described species (Carex fenghuangshanica S.F. Wang & T. Tang ex P.C. Li) that resembles Carex speciosa Kunth. was included (Li, 1999). Upon closer examination of Hong Kong specimens that were previously identified as C. speciosa (S.T. Dunn 5288, Jun 1908, San Tau, Lantau (AFCD); S.C. Ng 1333, 21 Apr 1998, Pokfulam, HK Is. (HKU, AFCD); S.C. Ng 1822, 28 Apr 1999, Mui Wo, Lantau (HKU); S.C. Ng 1892, 20 Jun 1999, Yi O, Lantau (HKU)), all of them turn out to be C. fenghuangshanica according to Dai et al. (2000). The identity of these Hong Kong specimens was confirmed by comparing them with the type specimens of C. fenghuangshanica deposited at the Beijing National Herbarium (PE).
These two species have similar habits and both have androgynous spikelets typical of the Section Radicales. However, they differ in the shape and character of their utricles, achenes and spikes. Utricles of C. fenghuangshanica are characterized by having many (>4) obvious and raised veins on each of the two dorsal faces, whereas C. speciosa always has only two raised veins, one at the middle of each of the two dorsal facing sides of the utricle, in addition to some tender and obscure veins (Fig. 1 & 2). Utricles of C. fenghuangshanica are also broadly ovate, whereas those of C. speciosa are elliptical. The achenes of C. fenghuangshanica have a broader shape than those of C. speciosa. Carex fenghuangshanica also has fewer spikes and broader spikelets than C. speciosa.
Li (1999) and Dai et al (2000) mentioned no additional locality for this species other than the type locality at Guangxi (Fenghuangshan, Gechang). Hong Kong is therefore a new locality for this species. The global status of this species, however, cannot be determined at this stage since the whole group is generally overlooked. Locally in Hong Kong, it is only found at four sites (Xing et al. 2000) in sparse forest at low altitude (50 – 250 m).
Bibliography
Anonymous. (1978). Check List of Hong Kong Plants. Agriculture and Fisheries Department Bulletin No. 1 (Revised), Hong Kong Herbarium, Hong Kong.
Anonymous. (1993). Check List of Hong Kong Plants. Agriculture and Fisheries Department Bulletin No. 1 (Revised), Hong Kong Herbarium, Hong Kong.
Barlow, B.A. (1997. Loranthaceae. Flora Malesiana 13: 209-401.
Bentham, G. (1861). Flora Hongkongensis. Lovell Reeve. London.
Chen, X.Q. and Koyama, T. (2000). Smilax. Flora of China 24: 96-115.
Dai, L.K., Liang, S.-Y., Tang, Y.C., Li, P.C. (eds.) (2000). Flora Reipublicae Popularis Sinicae. Science Press, Beijing.
Dunn, S.T. and Tutcher, W.J. (1912). Flora of Kwangtung and Hongkong (China). Royal Botanic Garden, Kew.
Kiu, H.S. (1988). Loranthaceae. Flora Reipublicae Popularis Sinicae. 24:86-158. Science Press, Beijing.
Li, P.C. (1999). New taxa of Carex L. (Cyperaceae) from China. Acta Phytotaxonomica Sinica. 37(2):156-176.
Xing F.W., Ng, S.C. and Chau, L.K.C. (2000). Gymnosperms and Angiosperms of Hong Kong. Memoirs of the Hong Kong Natural History Society. 23:21-136.
Fig. 1 Carex fenghuangshanica S.F. Wang & T. Tang ex P.C. Li.
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P.17-19
Some brief notes on Ligustrum punctifolium M. C. Chang
by Patrick Lai
Hong Kong Herbarium, AFCD
The Biodiversity Survey has identified a Ligustrum species, Ligustrum punctifolium, which has not been recorded in the Checklist of Hong Kong Plants. The species was first published in 1985 based on a specimen collected by Mr. Tsiang Ying on a tidal plain at Wukautin (now called Wu Kau Tang) in 1929. A review on the Ligustrum specimens in the Hong Kong Herbarium has been carried out. Two specimens collected by Mr. William Tutcher in 1914 (Herb no: HK18555 & HK18556) formerly identified as Ligustrum strongylophyllum Hemsl. were re-identified as Ligustrum punctifolium M. C. Chang based on the shorter petioles, smaller and brown glandular dotted leaves of the specimens. These two specimens were in fact collected at a time earlier than the type specimen collected by Tsiang in 1929. The locality of the specimens was recorded as "Cheung Mi". I guess it could be "Chung Mei" which is the river mouth of Bride’s pool flowing into the Plover Cove Reservoir. Apparently, the specimens were collected long before the reservoir was built when "Chung Mei" was still a coastal habitat of Tolo Harbour. As Chung Mei is the nearest tidal plain to the area Wu Ka Tang, it is likely that the Tsiang’s specimen was also collected in this location.
The species has recently been recorded in Shum Chung, Sam A Chung and Sam A Tsuen. It appears that all historical and present localities are restricted to the coastal areas of the Northeast New Territories. More importantly, the species has so far been recorded in Hong Kong and Vietnam only, hence, it is definitely one of the species that deserves our attention.
Visits to the three existing populations of the species were carried out earlier this year and the one at Sam A Chung within the Plover Cove Country Park was found to be the largest and in the best condition. The site is a sheltered tidal inlet with freshwater input from a stream. Individuals of L. punctifolium were found growing along the stream bank. All three populations were found fruiting in February this year and seeds from individuals of the three populations were collected. The seeds were germinated in the nursery and the initial germination rate was found to be quite high (approximately 40%). Special care will be given during seedling establishment. The next step will be to identify suitable sites for reintroduction after the seedlings have been successfully established.
Bibliography
Chang, M.C. (1985). Acta Phytotax. Sin. 23(1):53.
Merrill, E.D. & Chun, W.Y. (1930). Contributions to our knowledge of the Kwangtung Flora. Sunyatsenia 1:79.
Tutcher, W. (1914). Report of the Botanical and Forestry Department for the Year 1914.
P.19-20
Have you seen this plant?
by Richard Corlett
A few issues back (volume 14), I reported the first record in Hong Kong of Mimosa diplotricha (as M. invisa). This extraordinarily unpleasant Mexican weed is best described as "green barbed wire": a scrambling or climbing plant, with recurved spines on the 4-angled stems, and twice-pinnate leaves that close when touched. AFCD have tried to eliminate a large population at Ting Kok and there have been scattered sightings elsewhere. Please report any new populations to me and the AFCD
P.19
Is Tsiangia hongkongensis a synonym of Ixora chinensis?
by Richard Corlett
Tsiangia hongkongensis (Seem.) But, H.H. Hsue & P.T. Li is a mysterious Hong Kong endemic plant, known only from two specimens in the herbarium at Kew. Diane Bridson, in the latest Kew Bulletin, suggests that they are simply deformed specimens of the widespread Ixora chinensis Lam.
Bibliography
Bridson, D.M. (2000). The identity of Tsiangia (Rubiaceae). Kew Bulletin 55: 1011-1012.
P.20
Hong Kong's "Psychotria rubra" is Psychotria asiatica L.
by Richard Corlett
The common understorey shrub, Psychotria rubra, is one of the few plants every ecologist in Hong Kong knows – or, rather, thought they knew, since it turns out it is not P. rubra at all, but P. asiatica L. The story behind this name change spans the entire history of both modern plant nomenclature and the botanical exploration of South China.
The specimen of P. asiatica in the Linnean herbarium in London was probably collected by the great Swedish botanist Peter Osbeck, a pupil of Linnaeus who visited Guangzhou in 1751. This is the Osbeck who first described the Chinese white dolphins and after whom Linnaeus named the genus Osbeckia. Unfortunately, Linnaeus based his description of P. asiatica partly on this specimen and partly on an illustration of a species from Jamaica, since described as P. brownei Sprengel, although he clearly believed he was describing a plant from Asia, not the Caribbean.
This mess was not formally sorted out until 1964, when Petit selected the Asian specimen in London as the lectotype of P. asiatica L.. This still left the question of precisely where P. asiatica came from unresolved, but recent work by Davis et al. (2001) at Kew has shown that it is the same as the specimens from Guangdong, Hong Kong and Hainan which were previously named P. rubra (Lour.) Poir. At the same time, these specimens differ from specimens of the real P. rubra from Indochina.
Bibliography
Davis, A.P., Bridson, D., Jarvis, C. and Govaerts, R. (2001). The typification and characterization of the genus Psychotria L. (Rubiaceae). Botanical Journal of the Linnean Society 135: 35-42.
Fig. 1 Psychotria asiatica in fruit. (photo by Alvin Tang)
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P.20
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Porcupine! |
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