Bot. Bull. Acad. Sin. (2001) 42: 313-317

Long and Liu — A new species of Colocasia from China

Colocasia lihengiae (Araceae: Colocasieae), a new species from Yunnan, China

Chun-Lin Long^1,* and Ke-Ming Liu²

¹Kunming Institute of Botany, Chinese Academy of Sciences, Heilongtan, Kunming 650204, Yunnan, China

²Department of Botany, College of Life Science, Hunan Normal University, Changsha 410081, China

(Received May 9, 2000; Accepted October 2, 2000)

Abstract. A new species of Colocasia Schott, C. lihengiae C. L. Long et K. M. Liu, sp. nov., is described and illustrated. The species is restricted to the rainforest of Xishuangbanna in southern Yunnan, China. Diagnostic morphological characters that distinguish the new species from the related species, C. fallax Schott, are discussed. Chromosome numbers (2n=28) were observed in plants of C. lihengiae cultivated at the Kunming Botanical Garden.

Keywords: Araceae; China; Colocasia lihengiae; New species; Taxonomy; Xishuangbanna; Yunnan.

Introduction

Yunnan, a province in southwest China with an area of 394,000 km², is notable for its rich plant diversity. Over 15,000 vascular plants have been recorded from Yunnan. Since the 1830s more than 2,100 new species of vascular plants have been described from Yunnan and collected by botanists such as J. Anderson, J. M. Delavay, Prince Henri d'Orleans, A. Henry, E. H. Wilson, G. Forrest, E. E. Maire, F. Kingdon-Ward, H. Handel-Mazzetti, K. A. H. Smith, J. F. Rock, T. T. Yü, R. C. Ching, C. W. Wang, C. Wang, K. M. Feng and other Chinese botanists (Bao et al., 1998). Today, Yunnan is still one of the most interesting places for botanical exploration.

Colocasia (Araceae) is a tropical Asian genus. Until 1997, only about nine species had been described (Engler and Krause, 1920; Li, 1979; Sivadasan, 1982; Plucknett, 1983; Shaw, 1984; Sreekumari and Mathew, 1991a, b; Li and Wei, 1993; Hay, 1996; Mayo et al., 1997). In 1999, an additional species, Colocasia gaoligongensis, was described by Li and Long from a small area in western Yunnan, close to northern Myanmar (Burma).

In June 1998, we collected an aroid in a dense rainforest in valleys of southern Yunnan. This perennial herb with long stolons and large leaf blades, and with inflorescences lacking an appendix, was difficult to determine as belonging to Remusatia, Colocasia or Alocasia. Living plants and herbarium specimens were collected and brought to the Kunming Botanical Garden for cultivation. Further study of the morphology, especially of the ovules, revealed the plant to be a new species of Colocasia.

Materials and Methods

Three living plants were brought to Kunming. Before planting them in the greenhouse of the Kunming Botanical Garden at the Kunming Institute of Botany, most of the leaves were removed to reduce stress. The largest plant was grown in open ground; the other two were grown in pots.

Herbarium specimens were prepared from both field and greenhouse plants. They were deposited in the Herbarium of Kunming Institute of Botany (KUN). Both female and male flowers were observed under a microscope.

Root tips were collected for chromosome observations. The growing root tips were pretreated with 0.002 M 8-hydroxiquinoline for 2 h at room temperature (20 ± 2°C) and for an additional 2 h in a refrigerator (8 ± 2°C). They were subsequently fixed in ethanol-acetic acid (3:1) and kept in a refrigerator until observed. The fixed root tips were rinsed in water and hydrolyzed in a 1N hydrochloric acid at 60°C for 5 min. After washing in distilled water and removing the excess, the samples were submerged in Feulgen stain for 30 min, transferred into aceto-carmin and 45% acetic acid for 10 min, and squashed in 45% acetic acid. The chromosomes were then examined under a microscope (Nguyen, 1998).

Additional specimens similar to the new species were examined and recorded. In total, 16 herbarium specimens (ca. 80 individuals) of Colocasia were studied. These specimens are deposited in A/GH, CAS, HAST, HITBC, KUN, MO, NY, and PE.

Description

Colocasia lihengiae C. L. Long et K. M. Liu, sp. nov.—TYPE: CHINA. Yunnan Prov.: Mengla, Mengxing River

*Corresponding author. Tel: (0086) 871-522-3233; Fax: (0086) 871-515-0227; E-mail: long@mail.kib.ac.cn, or chunlinlong@ hotmail.com

Botanical Bulletin of Academia Sinica, Vol. 42, 2001

Figure 1. Illustration of Colocasia lihengiae C. L. Long et K. M. Liu, sp. nov. (drawn by Yitao Liu). a, flowering plant; b, inflorescence; c, synandrium; d, female flower; e, transverse section of ovary; f, enlargement of an ovule; g, spadix.

Long and Liu — A new species of Colocasia from China

watershed, in a valley with dense rainforest, 20 Jun 1998, Long Chun-lin & Li Meilan 9806 (holotype: KUN); Paratype: 18 Jul 1998, Long Chun-lin & Li Meilan 9824 (KUN), cultivated in Kunming Botanical Garden.

Figure 1

Colocasia fallax Schott similis, sed appendice absenti differt.

Terrestrial perennial herbs with stolons (stoloniferous runners) and an erect rhizome. Rhizome 4-8 cm long, 2-3 cm in diam.; stolons (stoloniferous runners) 6-12, trailing horizontally, non-branching, thin, pale green or pale purple, 70-80 cm long, 0.5 cm in diam., with dark green cataphylls; internodes cylindric, 15-25 cm long, without tubercles. Leaves 4-6; petiole cylindric, light green, reddish-purple, 80-120 cm long; blade peltate, sagittate-cordate, membranaceous, 30-40 cm long, 18-25 cm wide, upper surface glossy green, lower surface pale green; primary lateral veins 6 pairs, pale green; marginal vein inconspicuous. Inflorescences (4-) 5 (-6); peduncle cylindrical, pale green, 40-50 cm long, much shorter than petiole. Spathe constricted in the middle, lower convolute part (tube) yellowish green, 4-5 cm long, 2 cm in diam., nearly cylindrical; lamina oblong-lanceolate, golden yellow, 11-13 cm long, 4 cm wide, patent to reflexed. Spadix fragrant, female zone golden yellow, cylindrical, 2-2.5 cm long, 0.7 cm in diam., half as short as spadix; male zone cylindrical, yellow, 3.5 cm long, 0.6-0.8 cm in diam.; neutral flower zone between female and male zones, cylindrical, 1 cm long, 0.4-0.5 cm in diam.; appendix absent; female flower obovoid, carpels 3 or 4, ovary unilocular, placentae 2, parietal, ovules spindle shaped, nearly erect, numerous, stigma sessile, discoid; synandria 8-10-androus, ca. 0.1 cm long, yellow. Fruits not seen. Chromosome number: 2n = 28.

This species is gratefully dedicated to our advisor, Prof. Li Heng, who has contributed much to the study of Araceae in China. Her wide knowledge of Araceae and other monocots and her contribution to Chinese botany

are of great importance for a better understanding of aroids and of the flora of Yunnan.

Phenology

In the wild, flowering occurs between June and August; fruiting occurs between July and October. In the botanical garden, flowering occurs between July and October; fruiting occurs between August and late October. Pollinators were seen both in the field and in cultivated plants. These insects are small flies, probably members of the genus Colocasiomyia (H. Wang, pers. com.).

Distribution and Habitat

Colocasia lihengiae grows in clusters of 1-4 individuals in small populations at edges of and in forests in limestone areas at 600 m. Other aroids in the same habitats include Alocasia odora Koch, A. navicularis (C. Koch) C. Koch, A. longiloba Miq., Colocasia gigantea (Bl.) Hook. f., C. esculenta (L.) Schott, Pothos scandens L., Remusatia vivipara (Roxb.) Schott, and Rhaphidophora decursiva (Roxb.) Schott.

Discussion

Colocasia lihengiae is an attractive evergreen perennial herb with handsome foliage and fragrant inflorescences.

After a thorough search through the literature (Hook. f., 1893; Li, 1979; Li and Wei, 1993; Yoshino, 1994; Mayo et al., 1997; Nguyen, 1998; Li and Long, 1998, 1999), the closest species to our material appears to be Colocasia fallax Schott. But Colocasia lihengiae is clearly different from C. fallax. The most obvious difference is the absence of an appendix in spadix of C. lihengiae. The differences and similarities between these two species are shown in Table 1.

Botanical Bulletin of Academia Sinica, Vol. 42, 2001

The new species is also similar to some species of Alocasia (e.g. Alocasia odora and A. longiloba). It differs from these by its long stoloniferous runners, many ovules per ovary, and lack of an appendix in spadix. It is notable that the present new species possesses characteristics not only of Colocasia but also of Alocasia and Remusatia, which may be a result of natural hybridization.

Natural hybridization between Colocasia and Alocasia has been suggested and described. Yoshino (1994, 1995, 1998) succeeded in crossing Colocasia esculenta var. aquatilis and Alocaisa brisbanensis. Possible hybrids within Colocasia may occur in nature. Meiotic chromosome behavior in hybrids between Colocasia esculenta and C. gigantea have been reported (Okada and Hambali, 1989; Yoshino, pers. com., 1999). Based on the morphological characters of Colocasia lihengiae, determining its phylogenetic position is difficult. Molecular approaches and artificial hybridizations may reveal phylogenetic relationships between it and other taxa of Colocasia, Alocasia and Remusatia.

Acknowledgements. The field study was supported by the Chinese Academy of Sciences (KZ951-A1-104), the Natural Science Foundation of China (30170102) and the Natural Science Foundation of Yunnan Province (2001C0058M). Peter Boyce of the Royal Botanic Gardens, Kew helped us edit and modify the manuscript and gave useful comments. Li Meilan, Wang Hong and Yang Shixiong participated in the field trip. Zhou Qixing assisted in checking chromosome numbers. Luo Jifeng and Zhou Yilan maintained the plants in the Kunming Botanical Garden. Philip Thomas of the Royal Botanic Gardens, Edinburgh critically read the original manuscript. The authors are grateful to all of them.

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Long and Liu — A new species of Colocasia from China