郎边山茶 Camellia langbianensis (Gagnep.) P.H.HôCamellia langbianensis

Camellia langbianensis (Gagnep.) P.H.Hô   Câycỏ Việtnam 1(1): 537 (1991)

Types: VIETNAM. Lam Dong province: between B.-dle and Dankia commune, Langbian mountain, 1200–1300 m, 26 October 1930, Poilane 18648 (lectotype designated by Zhao et al. (2017: 173): P [P00754831]; isolectopypes: K [K000704329], L [L0012339], P [P00754832]). the image of the lectotype is available at https://science.mnhn.fr/institution/mnhn/collection/p/item/p00754831  

Description:Small evergreen tree, 3–5 m tall; branches pubescent when young and then glabrescent. Leaves alternate; petiole falcate, slightly curved, terete, 7–10 mm long, sparsely pubescent when young and then glabrescent; blades oblong, 20–32 cm long, 5–8 cm wide, coriaceous, apex acuminate, margin shallow serrate, base broadly cuneate or obtuse, above dark green, shiny and glabrous, below paler green, sparsely pubescent, lateral veins 15–20 pairs, impressed above, prominent below. Flowers solitary or 2–3 clustered, axillary, nodding, 5–6 cm diameter; pedicel 3.0–4.5 cm long, sparsely pubescent, light green; bracteoles 2(–3), scale-like, 2.0–2.5 mm long, 2.5–3.0 mm wide, light green, pubescent on both surfaces, persistent. Sepals 5(–6), orbicular or suborbicular, 5.0–9.0 mm long, 6.5–13 cm wide, light green, pubescent on both surfaces, margin membranous and ciliate, persistent. Petals 10–11(–12), suborbicular to pentagonal, light yellow, pink pigmentation on edges, 1.4–3.4 cm long, 1.9–3.5 cm wide, tomentose on the both surfaces, innermost ones united 2.0–3.0 mm at base. Stamens 220–250 in 3–4 series; filaments 1.8–2.7 mm long, yellow, inner ones pubescent at base, outer ones glabrous, united for 3–4 mm from base and adnate to innermost petals for 2.0–3.0 mm at base; anthers 2.0–2.5 mm long, 1.5–2.0 mm wide, light yellow. Gynoecium 5-locular, ovary superior, oblate spherical, ribbed, 3.0–3.5 mm long, 4.0–5.0 mm wide, tomentose; style 5, free, 2.0–2.4 cm long, tomentose. Capsule corky, 1.8–2.1 cm high, 4.5–5.5 cm wide, sparse pubescent, dehiscing distally into 5 valves, pericarp 1.5–2.0 mm thin, 1–2 seed per locule; columella stout, 1.1–1.3 cm long. Seed semispherical, 1.5–1.8 cm long, 1.0–1.2 cm wide, russety, glabrous.

Distribution and habitat: Camellia langbianensis is endemic to Vietnam, occurring in provinces of Lam Dong and Ning Thuan. It grows in evergreen broad-leaved forest at 1100–1300 m altitude.

Conservation status: The species is found in three locations (two in Lam Dong and one in Ninh Thuan) and has an extent of occurrence of less than 100 km2. It is known that the mountain Langbian has suffered from habitat loss, degradation and fragmentation in places. The main reason is due to tourism activities and deforestation for agricultural production. It was estimated that fewer than 200 individuals are in three populations. Therefore, it would be assessed as Critically Endangered (CR) according to IUCN categories and criteria (IUCN 2019).

Taxonomic affinities: According to the classification of Ming & Bartholomew (2007), C. langbianensis may be placed into section Piquetia (Pierre 1887: 119) Sealy (1958: 108) in the charecters of its leaves stalked, blades oblong, more than 20 cm long, flowers pedicellate, solitary or 2–3, in axillary or terminal, persistent bracteoles 2–3, persistent sepals 5, petals 5(–6), styles 3–5, capsule flattened, globose, with 5 indehiscent secondary ridges, 1–2 ovules per locule.

Vietnam: Lam Dong and Ning Thuan

 郎边山茶Camellia langbianensis (Gagnep.) P.H.Hô, Cayco Vietnam (Illustrated Flora of Vietnam) 1(1): 537 (1991) ≡ Dankia langbianensis Gagnepain Flora Indo-Chine [P.H. Lecomte et al.] Supplement: 198 (1939) 组：匹克茶组Piquetia。再次发现Phytotaxa 480 (1): 85 (2021)越南林同省B.-dle 和 Dankia 公社之间郎边山1200-1300米， 26/10/1930,Poilane 18648 ( 后选模式Zhao et al. (2017: 173):P [P00754831]; 等后选模式: K [K000704329], L [L0012339], P [P00754832])

描述：常绿小乔木，高3-5米；枝条幼时被短柔毛，后脱落。叶互生；叶柄镰刀形，稍弯曲，圆柱形，长7-10毫米，幼时被疏生短柔毛，后脱落；叶片长圆形，长20-32厘米，宽5-8厘米，革质，先端渐尖，边缘有浅锯齿，基部宽楔形或钝，上面深绿色，有光泽，无毛，下面浅绿色，被疏生短柔毛，侧脉15-20对，上面凹陷，下面突出。花单生或2-3朵簇生，腋生，有节，直径5-6厘米；花梗长3.0-4.5厘米，疏生短柔毛，淡绿色；小苞片2(-3)，鳞片状，长2.0-2.5毫米，宽2.5-3.0毫米，淡绿色，两面被短柔毛，宿存。萼片5(-6)，圆形或近圆形，长5.0-9.0毫米，宽6.5-13厘米，淡绿色，两面被短柔毛，边缘膜质，具缘毛，宿存。花瓣10-11(-12)，近圆形至五角形，淡黄色，边缘有粉红色色素，长1.4-3.4厘米，宽1.9-3.5厘米，两面被绒毛，最里面的花瓣基部合生2.0-3.0毫米。雄蕊3-4轮220-250枚；花丝长1.8-2.7毫米，黄色，基部内侧被短柔毛，外侧无毛，基部3-4毫米处合生，基部2.0-3.0毫米处贴生于最内侧的花瓣；花药长2.0-2.5毫米，宽1.5-2.0毫米，浅黄色。雌蕊群5室，子房上位，扁球形，有棱，长3.0-3.5毫米，宽4.0-5.0毫米，被绒毛；花柱5，离生，长2.0-2.4厘米，被绒毛。蒴果木栓质，高1.8-2.1厘米，宽4.5-5.5厘米，疏生短柔毛，上部开裂成5裂爿；果皮薄1.5-2.0毫米，每室1-2粒种子；轴柱粗壮，长1.1-1.3厘米。种子半球形，长1.5-1.8厘米，宽1.0-1.2厘米，粗糙无毛。

分布和栖息地： 郎边山茶（Camellia langbianensis）是越南特有的植物，分布于林同（Lam Dong）省和宁顺（Ning Thuan）省。它生长在海拔 1100-1300 米的常绿阔叶林中。

保护状况： 该物种分布在三个地方（两个在林同省，一个在宁顺省），分布范围不到 100 平方公里。据了解，其栖息地有的地方已经消失，有的地方退化，有的地方支离破碎。主要原因是旅游活动和为农业生产而砍伐森林。据估计，三个种群的数量不足 200 株。因此，根据世界自然保护联盟（IUCN）的分类和标准（IUCN 2019），该物种将被评估为极度濒危物种（CR）。

分类亲缘关系： 根据 Ming & Bartholomew（2007 年）的分类，C. langbianensis可归入Piquetia组(Pierre 1887: 119)，Sealy（1958: 108），叶片长圆形，超过20厘米长，花有花梗，单生或2-3朵，腋生或顶生，宿存小苞片2-3枚，宿存萼片5枚，花瓣5(-6)枚，花柱3-5枚，蒴果扁平，球形，有5条不裂的次棱，每室1-2颗胚珠。

越南特有的植物，分布于林同（Lam Dong）省和宁顺（Ning Thuan）省