Research Article |
Corresponding author: Pimwadee Pornpongrungrueng ( ppimwa@kku.ac.th ) Academic editor: Clifford Morden
© 2022 Natthawut Triyutthachai, Long-Fei Fu, Pramote Triboun, Yi-Gang Wei, Pimwadee Pornpongrungrueng.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Triyutthachai N, Fu L-F, Triboun P, Wei Y-G, Pornpongrungrueng P (2022) Three new species of Elatostema (Urticaceae) from Thailand. PhytoKeys 215: 37-50. https://doi.org/10.3897/phytokeys.215.94591
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Three new species of Elatostema (Urticaceae) from Thailand, E. kaweesakii Triyutth. & L.F.Fu, sp. nov., E. rubricaule Triyutth. & L.F.Fu, sp. nov. and E. saxatile Triyutth. & L.F.Fu, sp. nov., are newly described and illustrated. These new species can be distinguished by the presence of rhizome. Elatostema kaweesakii is similar to E. atroviride. Elatostema kaweesakii is a lithophyte growing in limestone crevices. It differs from E. atroviride by its large swollen rhizome, glabrous stem, glabrous receptacle, number of tepal in staminate flower, absence of tepal in pistillate flower, presence of staminodes in pistillate flower and smooth achene. Elatostema rubricaule and E. saxatile are found on sandstone habitats. They have distinct flattened and disk-like rhizome. Elatostema rubricaule is distinguished by its distinct sulcate and reddish stem with flattened and disc-like rhizome and chartaceous leaves with entire margin. Elatostema saxatile resembles E. bulbiferum but differs by its flattened and disc-like rhizome, acute leaf apex, glabrous receptacle in pistillate inflorescences, presence of staminodes in pistillate flower, and its sandstone habitat. Descriptions, distribution, ecological and phenological data are provided.
Flora of Thailand, limestone, nettle family, rhizomatous plant, Rosales, sandstone, taxonomy
Elatostema J.R. Forst. & G. Forst. is a large genus of Urticaceae containing several hundred species distributed throughout tropical and subtropical Asia (
The first checklist of Elatostema (including Pellionia) in Thailand documented 14 species (
As part of ongoing research into the flora of Thailand, the authors undertook extensive field investigations and collected three unknown specimens of Elatostema from the northeastern region of Thailand. After a careful comparison among specimens, it was clear that these specimens belong to the clade that includes Pellionia and Elatostema in
Between 2016 and 2022, the authors conducted several field trips throughout Thailand. The herbarium collections from AAU, BCU, BK, BKF, C, HNU, IBK, K, L, KKU, P, PSU, QBG and SING (Thiers 2022) were examined mainly by the first author. All morphological characters were measured and compared based on dried specimens from field and herbarium collections.
Elatostema kaweesakii is similar to E. atroviride W.T. Wang but differed by its large swollen rhizome, staminate inflorescences with 2–7 cm long peduncle, receptacle rectangular, glabrous, staminate flower with 5 ovate tepals, pistillate inflorescences with 5–10 mm long peduncle, receptacle rectangular, glabrous, pistillate flower without tepals, staminode present and achene smooth (Table
Comparison of Elatostema atroviride, E. bulbiferum, E. kaweesakii, E. rubricaule and E. saxatile.
Characters | E. atroviride | E. kaweesakii | E. rubricaule | E. saxatile | E. bulbiferum |
---|---|---|---|---|---|
Habitat | lithophyte in limestone soils | lithophyte in limestone crevices | lithophyte on sandstone rocks | lithophyte on sandstone rocks | lithophyte in limestone crevices |
Rhizome | slender rhizome or stoloniferous | large swollen rounded rhizome | flattened, disk-like rhizome | flattened, disk-like rhizome | swollen rounded rhizome |
Stem | Simple or branched, greenish, pubescent | Simple or branched, greenish, glabrous | Simple, reddish, glabrous | Simple or branched, greenish, glabrous | Simple or branched, greenish, glabrous |
Nanophyll | absent | absent | absent | present | present |
Leaf margin | dentate | serrate to dentate | entire | serrate | serrate |
Leaf apex | acuminate | acuminate | obtuse | acute | acuminate to caudate |
Staminate inflorescences: type | Capitate | Capitate | Umbellate | Umbellate | Umbellate |
Staminate inflorescences: receptacle | elliptic, chartaceous, pubescent | rectangular, chartaceous, glabrous | absent | absent | absent |
Staminate inflorescences: peduncle | 2–5 mm long | 2–7 cm long | 2– 3 cm long | 1–5 cm long | 2–5 cm long |
Staminate flower: tepal number | 4 | 5 | 5 | 5 | 5 |
Pistillate inflorescences: type | capitate | capitate | capitate | capitate | capitate |
Pistillate inflorescences: receptacle | oblong, membranous, pubescent | rectangular, chartaceous, glabrous | elliptic, membranous, glabrous | elliptic, membranous, glabrous | elliptic, membranous, pubescent |
Pistillate inflorescences: peduncle | 2–4 mm long, glabrous | 5–10 mm long, glabrous | sessile to subsessile, glabrous | 0.5–5 mm long, glabrous | 0–2 mm long, glabrous |
Pistillate flower: tepal number | 3 | absent | 5 | 5 | 5 |
Pistillate flower: staminode | absent | 3 | 5 | 5 | absent |
Achene | 6–8 ribbed | smooth | smooth | smooth | smooth |
Thailand. Loei: Nong Hin district, 17°7.3'N, 101°56.05'E, 360 m alt., 9 August 2022, Triyutth. 332 (holotype KKU!; isotypes AAU!, BKF!).
Perennial herbs, lithophytic, monoecious, rhizomatous. Rhizome rounded, 2–20 cm in diam., brownish. Stems 15–50 cm tall, simple or branched, succulent, greenish, glabrous. Stipules 2, persistent or sometimes caducous in reproductive stage, linear or lanceolate, 4–7 × 1–3 mm, membranous, glabrous. Nanophylls absent. Leaves distichous, alternate; petiole 0.5–1 cm long, greenish, glabrous; lamina asymmetrically ovate to elliptic, 5–20 × 3–10 cm, base oblique, margin serrate to dentate, apex acuminate, chartaceous; venation pinnate, major basal lateral veins present; upper and lower surfaces greenish, glabrous, cystoliths fusiform, 0.2–0.5 mm long. Staminate inflorescences axillary, solitary, capitate, 1.5–2.0 cm in diam.; peduncle 2–7 cm long, glabrous or pubescent; receptacle rectangular, 0.6–1.0 × 0.6–1.0 cm, chartaceous, glabrous; bracts ovate, connate at base, membranous, glabrous; bracteoles lanceolate, 0.6–0.8 × 0.2–0.3 mm, membranous, pubescent. Staminate flowers 80–100 per inflorescence, sessile to subsessile, glabrous; tepals 5, ovate, 1.0–1.5 × 1.0–1.5 mm, apex acuminate, membranous, pubescent; stamens 5, filaments 1.0–1.5 mm long, anthers 0.6–0.8 mm long. Pistillate inflorescences axillary, solitary, capitate 5–10 mm in diam., peduncle 0.5–1.0 cm long, glabrous; receptacle rectangular, 6–8 × 6–8 mm, chartaceous, glabrous; bracts ovate, 0.8–1.0 × 0.5–0.6 mm, membranous, pubescent; bracteoles lanceolate, 0.4–0.6 × 0.2–0.3 mm, membranous, pubescent. Pistillate flowers 40–100 per inflorescence, sessile to subsessile, glabrous; tepals absent; staminodes 3, oblong to linear, 0.2–0.3 mm long; ovary superior, ovoid, 0.3–0.5 mm long. Achenes ellipsoid, 0.8–1.2 mm long, brownish, smooth.
Currently known only from Loei province in northeastern Thailand.
Occur in limestone crevices.
Flowering and fruiting in April–December.
This species is named in honor of Mr Kaweesak Keeratikiat, who first discovered the plants.
This species was found in fewer than 5 locations at Nong Hin district, Loei province, Thailand. Moreover, it has a very small population and very restricted distribution, and the number of mature individuals is fewer than 250. According to
Thailand. Loei: Nong Hin district, 16 December 2013, S. Saengvirotjanapat 635 (QBG!), ibid., 20 April 2021, Triyutth. 329 (KKU!).
This species is similar to E. atroviride in their habitat as lithophytes growing in limestone crevices. Both species have rounded rhizome, absence of nanophyll and a similar shape of leaves. However, it differs from E. atroviride by several characters such as its large rounded rhizome (small size of rhizome in E. atroviride), staminate inflorescences with 2–7 cm long peduncle (vs 2–5 mm long), receptacle rectangular and glabrous (vs elliptic and pubescent), staminate flower with 5 tepals (vs 4 tepals), pistillate inflorescence with 5–10 mm long peduncle (vs 2–4 mm long), absence of tepals in pistillate flower (vs 3 tepals), 3 staminodes (vs staminode absent) and achene smooth (vs 6–8 ribbed).
Elatostema rubricaule differs from other Thai Elatostema by its distinct sulcate and reddish stem with flattened and disk-like rhizome and chartaceous leaves with entire margin. It grows on seasonally moist sandstone rock (Table
Thailand. Buengkan: Wat A-Hong Silawas, 18°25.47'N, 103°28.2'E, 160 m alt., 13 September 2017, Triyutth. 201 (holotype KKU!; isotypes AAU!, BKF!, IBK!, K!).
Perennial herbs, lithophytic, monoecious, rhizomatous. Rhizome flattened, disk-like, 1–3 cm in diam., brownish. Stems 5–25 cm tall, simple, sulcate, succulent, reddish, glabrous. Stipules 2, persistent or sometimes caducous in reproductive stage, linear or lanceolate, 2.0–2.5 × 0.5–1.5 mm, membranous, glabrous. Nanophylls absent. Leaves distichous, alternate; petiole 0.5–2.0 mm long, reddish, glabrous; lamina asymmetrically lanceolate to elliptic, 3–5 × 0.5–1.5 cm, base asymmetrical attenuate, margin entire, apex obtuse, chartaceous; venation pinnate, major basal lateral veins absent, lateral veins 5–7 pairs; upper surface greenish, glabrous, cystolith fusiform, 0.2–0.5 mm long; lower surface cinereous, glabrous, cystoliths fusiform, 0.2–0.5 mm long. Staminate inflorescences axillary, solitary, umbellate; peduncle 2–3 cm long, glabrous; receptacle absent; bracts lanceolate, 0.8–1.0 × 0.3–0.5 mm, membranous, pubescent; bracteoles lanceolate, 0.6–0.8 × 0.2–0.3 mm, membranous, pubescent. Staminate flowers 5–10 per inflorescence; pedicel 1–3 mm long, glabrous; tepals 5, ovate to oblong, 1.0–1.5 × 1.0–1.5 mm, apex obtuse, membranous, glabrous; stamens 5, filaments 1.5–2.0 mm long, anthers 0.6–1.0 mm long. Pistillate inflorescences axillary, solitary, capitate 5–8 mm in diam., sessile to subsessile, glabrous; receptacle elliptic, 2.0–2.5 × 1.0–1.5 mm, membranous, glabrous; bracts lanceolate, 0.4–0.6 × 0.2–0.3 mm, membranous, pubescent; bracteoles lanceolate, 0.3–0.4 × 0.2–0.3 mm, membranous, pubescent. Pistillate flowers 50–80 per inflorescence; pedicel 0.5–1.0 mm long, glabrous; tepals 5, lanceolate to oblong, 0.8–1.2 × 0.2–0.4 mm, membranous, pubescent; staminodes 5, linear, 0.2–0.4 × 0.1–0.2 mm; ovary superior, ovoid, 0.3–0.5 mm long. Achenes ellipsoid, 0.5–0.8 mm long, brownish, smooth.
Currently known only from the type locality in northeastern Thailand.
Occurs on seasonal moist sandstone rocks in shaded areas.
Flowering and fruiting in July–October.
Latin ruber, red, and caulus, stem, alluding to stem color of the new species.
Elatostema rubricaule is currently known only from the type locality, which is not a protected area, and the number of mature individuals is fewer than 1,000. According to
Thailand. Buengkan: Wat A-Hong Silawas, 18°25.47'N, 103°28.2'E, 160 m alt., 28 April 2018, Triyutth. 269 (KKU!).
This species differs from other Thai Elatostema by its habitat. Most species of Elatostema are dwelling on limestone, stream bank, gorges and caves in evergreen forest, but E. rubricaule was found on moist sandstone rocks near the bank of Mekong River in Buengkan Province in the northeastern part of Thailand. The most distinguished characters of this species are the flattened and disk-like rhizome, sulcate and reddish stem, chartaceous leaves with entire margin and umbellate staminate inflorescences.
Elatostema saxatile is similar to E. bulbiferum Kurz, but differs by its flattened and disk-like rhizome, receptacle of pistillate inflorescences glabrous, staminode in pistillate flower 5, acute leaf apex and its sandstone habitat (Table
Thailand. Nakhon Phanom: Tad Kham Waterfall, 17°57.228'N, 104°9.6'E, 160 m alt., 13 September 2017, Triyutth. 200 (holotype KKU!; isotypes AAU!, BKF!, IBK!).
Perennial herbs, lithophytic, monoecious, rhizomatous. Rhizome flattened, disk-like, 2–7 cm in diam., brownish. Stems 5–35 cm tall, simple or branched, succulent, greenish, glabrous. Stipules 2, persistent or sometimes caducous in reproductive stage, linear or lanceolate, membranous, glabrous. Nanophylls lanceolate to oblanceolate, 0.5–1.5 × 0.2–1.0 cm, chartaceous, glabrous, cystoliths fusiform. Leaves distichous, alternate; petiole 1–3 mm long, glabrous or puberulous; lamina asymmetrically elliptic to obovate, 1.5–7.0 × 0.5–3.0 cm, base oblique, margin serrate, apex acute, chartaceous; venation pinnate, major basal lateral veins absent, lateral veins 5–7 pairs; upper surface green, glabrous, cystolith fusiform, 0.2–0.5 mm long; lower surface greenish or cinereous, glabrous, cystolith fusiform, 0.2–0.5 mm long. Staminate inflorescences axillary, solitary, umbellate; peduncle 1–5 cm long, glabrous; receptacle absent; bracts lanceolate, 0.6–1.0 × 0.3–0.4 mm, membranous, pubescent; bracteoles lanceolate, 0.5–0.8 × 0.2–0.3 mm, membranous, pubescent. Staminate flowers 10–30 per inflorescence; pedicel 1.0–1.5 mm long, glabrous; tepals 5, ovate to oblong, 1.0–1.5 × 1.0–1.5 mm, apex obtuse, membranous, glabrous; stamens 5, filaments 1.0–1.5 mm long, anthers 0.6–1.0 mm long. Pistillate inflorescences axillary, solitary, capitate, 2–8 mm in diam., subsessile to pedunculate; peduncle 0.5–5.0 mm long, glabrous; receptacle elliptic, 2–4 mm in diam., membranous, glabrous; bracts lanceolate, 0.2–0.3 × 0.8–1.0 mm, membranous, pubescent; bracteoles lanceolate, 0.2–0.3 × 0.5–0.8 mm, membranous, pubescent. Pistillate flowers 20–50 per inflorescence; pedicel 0.5–1.5 mm long, glabrous; tepals 5, lanceolate, 0.8–1.2 × 0.2–0.4 mm, membranous, pubescent; staminodes 5, oblong, 0.1–0.2 × 0.1–0.2 mm; ovary superior, ovoid, 0.4–0.8 mm long. Achenes ellipsoid, 0.8–1.2 mm long, brownish, smooth.
Northeastern Thailand.
Occurs on seasonal moist sandstone rocks in dry evergreen forest, at 100–200 m alt.
Flowering and fruiting in May–October.
The specific epithet refers to the habitat of this plant that dwelling on the rock.
This species was found scattered in ca. 6 locations in the Northeastern part of Thailand and the number of mature individuals is fewer than 1,000. According to
Thailand. Buengkan: Chet Si Waterfall, 14 September 2017, Triyutth. 202 (KKU!), ibid., 27 April 2018, Triyutth. 266 (KKU!), 267 (KKU!), Chanean Waterfall, 14 September 2017, Triyutth. 203 (KKU!), Phu Wua, 21 May 2004, R. Pooma et al. 4201 (BKF!), 4202 (BKF!), 4191 (BKF!), ibid., 28 December 2011, M. Norsaengsri & N. Tathana 8707 (QBG!), ibid., 13 July 2016, Triyutth. 97 (KKU!), 98 (KKU!), Phu Sing, 26 August 2001, R. Pooma et al. 2694 (BKF!), Phu Tok, 27 April 2018, Triyutth. 268 (KKU!), Phu Tok Noi, 22 June 1995, C. Niyomdham 4448 (BKF!), ibid., 21 June 1997, C. Niyomdham 5052 (BKF!), Wat Tham Phra, Phu Wua, 20 May 2014, S. Sirimongkol et al. 593 (BKF!); Nakhon Phanom: Tad Kham Waterfall, 25 August 2001, R. Pooma et al. 2652 (BKF!), ibid., 13 September 2017, Triyutth. 199 (KKU!).
Elatostema saxatile was found growing on the sandstone rocks in Buengkan and Nakhon Phanom Provinces, in the Northeastern part of Thailand. This species is similar to E. bulbiferum in the presence of rhizome, presence of nanophyll and umbellate staminate inflorescences, but differed by its flattened and disc-like rhizome (vs rounded rhizome in E. bulbiferum), receptacle of pistillate inflorescences glabrous (vs pubescent), staminode in pistillate flower 5 (vs absent), acute leaf apex (vs acuminate to caudate apex). Moreover, E. saxatile was found on sandstone while E. bulbiferum was found on limestone substrates.
We are grateful to the Directors, Curators and staff of AAU, BCU, BK, BKF, C, HNU, IBK, K, KKU, L, P, PSU, QBG and SING for making the materials available for this study. This work was supported by the Applied Taxonomic Research Center, Khon Kaen University grant ATRC_R6102 and the Research Fund for Supporting Lecturer to Admit High Potential Student to Study and Research on His Expert Program Year 2016 from Graduate School and Faculty of Science, Khon Kaen University, the Carlsberg Foundation for the Flora of Thailand project, the National Natural Science Foundation of China (31860042) and the Light of West China Program of the Chinese Academic of Sciences ([2020]82).