Hydrangea section Cornidia, currently consisting of 19 accepted taxa, occurs from Mexico to Chile and Argentina, with one species in southeast Asia. Its representatives are root-climbing lianas which may grow up to 60 m high in the tree canopy of temperate to (sub)tropical forests. Our extensive field work throughout its distribution area, study of herbarium specimens and ongoing molecular studies have resulted in the discovery of species new to science, as well as new insights into the circumscription of many taxa. We here present amended descriptions for seven Hydrangea species of Central and South America and discuss the taxonomical situation of two Colombian Hydrangeas, including an identification key, illustrations, and distribution maps. Field work was carried out in Costa Rica, Panama, Ecuador and Peru, including exploration in areas where the genus had not been collected before. These specimens and observations were complemented with the study of specimens of 41 herbaria of North, Central and South America, as well as Europe. Detailed morphological studies of all species were carried out, based on living plants in their natural habitat, as well as on dried specimens from our own collections and all available herbarium material. Type material was studied in detail for all species concerned. Based on an extensive number of morphological characters, combined with distribution patterns, phenological differences and ecological preferences, including molecular data in most cases, Hydrangea peruviana and H. oerstedii are clearly distinct taxa, as well as the other seven species mentioned here, which had been synonymized with either of these two species. The present study results in the recognition of 26 species in section Cornidia and exemplifies the urgent need for profound taxonomic studies in plants, as in many families we do not dispose of well-circumscribed units for conservation to mitigate the already occurring unprecedented loss of biodiversity.

中文翻译：

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在厄瓜多尔的一种濒危物种绣球花（Hydrangea peruviana）和在哥斯达黎加和巴拿马很常见的绣球绣球（Oystedii），以及威胁中美洲和南美绣球花的七种绣球花

绣球花科尼迪亚节目前由19个公认的分类单元组成，分布于墨西哥，智利和阿根廷，东南亚有一种。它的代表是攀根的藤本植物，在温带至（亚）热带森林的树冠中可以长到60 m高。我们在其分布区域的广泛野外工作，标本室标本的研究和正在进行的分子研究均导致发现了科学新物种，并对许多生物群的限制有了新见解。我们在此提供对中美洲和南美洲的七种绣球花物种的修订说明，并讨论两种哥伦比亚绣球花的分类学情况，包括识别码，插图和分布图。在哥斯达黎加，巴拿马，厄瓜多尔和秘鲁进行了实地工作，包括在以前从未收集过该属的地区进行探索。这些标本和观测资料是对北美，中美洲和南美洲以及欧洲的41种草标本的研究的补充。基于自然栖息地中的活植物，以及我们自己收集的干燥标本和所有可用的植物标本室材料，对所有物种进行了详细的形态学研究。对所有相关物种的类型材料进行了详细研究。根据广泛的形态特征，结合分布模式，物候差异和生态偏好（包括大多数情况下的分子数据），绣球花和鸢尾花明显是不同的分类单元，以及此处提到的其他七个物种，这已经是这两个物种的同义词。本研究结果认识到了在科尼迪亚节中的26种物种，并例证了对植物进行深入分类学研究的迫切需要，因为在许多家庭中，我们没有丢弃保护范围广的单位来减轻已经发生的前所未有的生物多样性丧失。