Data From: Inflorescence and flower development in Orchidantha chinensis T. L. Wu (Lowiaceae; Zingiberales): similarities to inflorescence structure in the Strelitziaceae

The monotypic Lowiaceae remains the least known family in the plant order Zingiberales, yet it holds an important key to unraveling the phylogenetic placement of the families Musaceae, Heliconiaceae, Strelitziaceae, and Lowiaceae. After nine phylogenetic studies the (Lowiaceae, Strelitziaceae) clade is the only stable clade that has emerged in this half of the order. This study was undertaken to verify the unusual inflorescence and flower structure in Orchidantha, and to search for new characters that might be used in future phylogenetic analyses. We describe both inflorescence and flower development in a previously unstudied species, confirm inflorescence morphology in the genus, and compare the structure of the inflorescence in the Lowiaceae with that of the Strelitziaceae, its potential sister group. The inflorescence of Orchidantha is born at the end of a vegetative shoot and is composed of two lateral branches that each bear four bracts and a single flower, before aborting. The fourth bract and its associated flower form the highly reduced flower cluster (florescence) that characterizes this genus. In technical terms Orchidantha has a polytelic synflorescence that lacks a main florescence (it has a truncated polytelic synflorescence) and bears solitary flowers in coflorescences on determinate enriching branches. The enriching branches produce a fixed number of bracts before aborting (i.e., they are special paracladia). Many of these features are shared with the Strelitziaceae. Similarities between the Lowiaceae and Strelitziaceae include inflorescence structure, the presence of a long prolongation of the ovary, and a delay in the formation of the third sepal during flower development, a character that is also shared with the Musaceae. Inflorescence and flower structure is now well established in this small, but important family.

单型的兰花蕉科（Lowiaceae）仍是姜目（Zingiberales）中研究程度最低的类群，但其却是解析芭蕉科（Musaceae）、蝎尾蕉科（Heliconiaceae）、旅人蕉科（Strelitziaceae）以及兰花蕉科自身系统发育位置的关键所在。过往已有9项系统发育研究表明，（兰花蕉科+旅人蕉科）演化支（clade）是该目这一支系中唯一得到稳定支持的演化支。本研究旨在验证兰花蕉属（Orchidantha）异常的花序（inflorescence）与花部结构，并挖掘可用于后续系统发育分析的新性状。我们对一种此前未被研究过的兰花蕉属物种开展了花序与花部发育过程的描述，确认了该属的花序形态，并将兰花蕉科的花序结构与其潜在姊妹群旅人蕉科进行了对比。兰花蕉属的花序生于营养枝顶端，由两条侧生分枝构成，每条分枝在败育前可着生4枚苞片与1朵单花。其中第4枚苞片及其对应的单花共同构成了该属标志性的极度简化花簇（florescence）。从专业角度而言，兰花蕉属具有无主花序的多歧聚伞复花序（polytelic synflorescence），属于截短型多歧聚伞复花序，且在有限增殖分枝上着生单花于副花序（coflorescences）中。此类增殖分枝在败育前会产生固定数量的苞片，即特化副枝（paracladia）。其中诸多特征与旅人蕉科高度相似。兰花蕉科与旅人蕉科的共性包括花序结构、子房的长延伸结构，以及花发育过程中第三枚萼片形成延迟这一性状——该性状同样存在于芭蕉科中。如今，这一小型却至关重要的类群的花序与花部结构已得到充分阐明。