Lilium longiflorum var. longiflorum (Liliaceae), a neglected lily of Taiwan

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Introduction
Lilium L. is the type genus of Liliaceae which comprises about 110 species distributed in subtropical to alpine regions of the northern hemisphere, especially in East Asia (Chen et al. 2000, Tamura 1998. The characteristic species of this genus are bulbiferous perennial herbs, with sessile or sub-sessile leaves, terminal inflorescences of colorful, nectar-bearing flowers, 3-loculed superior ovaries with numerous ovules, and loculicidal capsules with flattened seeds (Chen et al. 2000, Utech 2002, Ying 2000. In Taiwan, four taxa were treated in the second edition of Flora of Taiwan (Ying 2000), namely L. callosum Siebold & Zucc., L. formosanum Wallace, L. longiflorum Thunb. var. scabrum Masam., and L. speciosum Thunb. var. gloriosoides Baker. Among these, L. formosanum and L. longiflorum var. scabrum are similar in morphology and classified into section Leucolirion, which includes species with trumpet-shaped flowers, recurved tepals and filaments and a relatively large stigma (Comber 1949).
The record of L. longiflorum in Taiwan can be traced back to Henry (1896), who compiled the first comprehensive plant list of Taiwan. He recorded this species in Tamsui and the South Cape region. In 1906, Matsumura andHayata (1906) confirmed Henry's record and reported specimens from Senton and Biōritsu. Kawakami (1910) recorded this species in Taiwan without location and specimen information. Hayata (1917) included L. longiflorum in his list of Taiwanese plants, stating that the specimen was not found by him, but that the record might have come from the survey of Matsumura and Hayata (1906). Sasaki (1928) and Masamune (1936) recorded this species on the east coast of Taiwan in Lutao and Lanyu. Masamune (1939) However, Liu and Ying (1978) and Ying (2000) did not accept this taxon and considered L. japonicum var. scabrum as a synonym of L. longiflorum var. scabrum. The records of L. longiflorum of Sasaki (1928) and Masamune (1936) were treated as misinterpretations of L. longiflorum var. scabrum by Liu and Ying (1978) and Ying (2000).
Upon visiting Lanyu for the first time in 2009, the author noticed a native lily that had white flowers without purplish stripes. This specimen was different from the other taxa native to Taiwan, and plants were collected for identification on a subsequent visit to Lanyu. After reviewing the relevant literature, this lily was identified as L. longiflorum var. longiflorum, and was mentioned only in some informal records provided by local plant enthusiasts in the online forum, Nature Campus (Ahsiang 2014), and on Facebook (Yang 2017). Although many photos and morphological comparisons were provided for identification, formal records with detailed morphological description, specimen examinations, distribution maps, and conservation status were needed for this taxon.

Materials and methods
Study materials were obtained from herbarium sheets and field investigation. The following herbaria were examined: HAST, TAI, TAIF, TCF, TNM, and PPI, and the herbarium acronyms were those given by Thiers (2020). Voucher specimen were deposited in TCF and TAIF. Evaluation of conservation status of L. longiflorum var. longiflorum and L. longiflorum var. scabrum of Taiwan followed the criteria of Editorial Committee of the Red List of Vascular Plants of Taiwan (2017).  (Fig. 1).

Distribution
Distributed in Kyusyu (Yakushima and Tanegashima) and the Ryukyus of Japan (Hayashi 2016). In Taiwan, this variety is found in Lutao, Lanyu, and Pengchia Islet, in the exposed seashore and hills.

Identification keys
Key to Lilium taxa of Taiwan   1 Flowers not trumpet-like, often nodding; tepals strongly recurved 2 -Flowers trumpet-like, horizontal; tepals recurved only at apex 3 Haw (1986) averred that L. longiflorum might be a naturalized plant rather than a native one in Taiwan, as this species was cultivated in a graveyard in the Ryukyus, and could have been introduced into Taiwan in the same way. However, the populations of L. longiflorum var. scabrum scattered on the coastal areas of northern Taiwan had scabrous stems, which is different from the Japanese plants, and thus could not be naturalized. The other taxon, L. longiflorum var. longiflorum was only found in a few islands. If this distribution pattern was formed by human activity, then some unique custom of this plant would have been expected to be found, but no such custom was found in these islands; therefore, the distribution pattern of L. longiflorum var. longiflorum could only be explained by natural colonization and not by human activity. Lilium longiflorum Thunb. var. longiflorum. A habitat B habit C leaf adaxial surface D leaf abaxial surface E tepal adaxial surface F tepal abaxial surface G stamen H pistil. Scale bar = 3 cm.
Lilium longiflorum Thunb. var. longiflorum. A habitat B habit C leaf adaxial surface D leaf abaxial surface E tepal adaxial surface F tepal abaxial surface G stamen H pistil. Scale bar = 3 cm.